JP2014035509A - Micro-mirror element and mirror array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micro-mirror element and a mirror array that are able to achieve stable drive at a low cost.SOLUTION: The gravity center of a movable electrode 53 is separate from a rotation axis α. This enables a large rotation with a low voltage and eliminates the need for a driver or the like for applying a high voltage. Consequently a low cost can be achieved. Additionally, since the gravity center G of a mirror structure 5 is on the rotation axis α, the mirror structure 5 is prevented from being rotated around the rotation axis α even if subjected to disturbance. Accordingly, stable rotation can be achieved.

Description

  The present invention relates to a micromirror element and a mirror array used in an optical switch.

  2. Description of the Related Art In recent years, in the field of optical communication, it has been realized that large-capacity optical transmission is performed by WDM (Wavelength Division Multiplexing) technology in which one optical signal is associated with one wavelength and wavelength-division multiplexed. With the development of such optical communication technology, an optical switching device that switches a path without converting an optical signal into an electrical signal or the like has attracted attention. Among these, as a technology for realizing small size, light weight, and low cost, a spatial optical system optical switching device using an optical MEMS (Micro Electro Mechanical Systems) technology has attracted attention. For example, a wavelength selective switch (WSS) that can select an arbitrary wavelength from several tens of wavelengths and output the selected wavelength to any of a plurality of output fibers has been proposed. The most characteristic component of this wavelength selective optical switch is a micromirror array in which a plurality of micromirror elements are arranged at high density.

  In the micromirror array, mirror elements (micromirror elements) are arranged one-dimensionally or two-dimensionally. As shown in FIG. 18, the mirror element includes a mirror 301 having a substantially rectangular shape in plan view, a pair of spring members 302 that are connected to opposite sides of the mirror 301 and rotatably support the mirror 301, and a spring of the mirror 301. And an electrode 303 disposed at a predetermined interval on one side to which the member 302 is not connected. In such a mirror element, the mirror 301 is grounded, and a positive or negative voltage is applied to the electrode 303, whereby the mirror 301 is attracted by electrostatic attraction and the mirror 301 is rotated around an axis connecting the pair of spring members 302. Can be rotated.

  In the wavelength selective optical switch having such a mirror array, the output fiber is switched by greatly changing the rotation angle of the mirror 301, and the optical power is changed by slightly changing the rotation angle of the mirror 301. Adjustments are being made. For this reason, the micromirror element is required to greatly change and slightly change the rotation angle of the mirror.

JP 2010-185931 A JP-A-2005-043674 US Pat. No. 6,384,952 U.S. Pat. No. 7,911,672

Norinao Komura et al., FISHBONE-SHAPED VERTICAL COMBACTUATOR FOR DUAL-AXIS 1-D ANALOG MICRO MIRROR ARRAY, 2E4.132, p.980-983, TRANSDUCERS'05, The 13th International Conference on Solid-State Sensors, Actuators and Microsystems , Seoul, Korea, June 5-9, 2005 Jin-che Tsai and Ming C. Wu, Gimbal-Less MEMS Two-Axis Optical Scanner Array With High Fill-Factor, JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, Vol. 14, NO.6, DECEMBER 2005, p.1323-1328 Jin-che Tsai and Ming C. Wu, Design, Fabrication, and Characterization of a High Fill-Factor, Large Scan-Angle, Two-Axis Scanner Array Driven by a Leverage Mechanism, JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, Vol. 15, NO. 5, OCTOBER 2006, p.1209-1213

  However, in order to rotate the mirror largely, it is generally necessary to apply a high voltage to the electrode 303, so a special IC driver is used. However, since this IC driver is expensive, the cost of the optical switch is low. In order to achieve this, driving at a low voltage has been desired. Therefore, as shown in FIG. 19, a movable electrode 304 is provided on one side parallel to the rotation axis of the mirror 301, and the fixed electrode 303 is disposed to face the movable electrode 304. Has been proposed to achieve a large rotation angle so that a high torque can be obtained even when the applied voltage to the electrode 303 is low. However, in this case, since the ratio of the mirror width to the mirror pitch, that is, the fill factor becomes small, it becomes difficult to secure a sufficient equivalent band of the optical signal in order to switch the optical path in units of wavelengths.

  Further, when the mirror is rotated minutely, the optical power is adjusted by this minute rotation, so that the optical power fluctuates when the rotation angle fluctuates due to disturbance. For this reason, it has been desired to realize a stable rotation even when a disturbance occurs.

  Therefore, an object of the present invention is to provide a mirror array that can realize stable driving at low cost.

  In order to solve the above-described problems, a micromirror element according to the present invention includes a microelectrode provided with a fixed electrode provided on a substrate and a structure that is rotatably disposed apart from the substrate. A mirror element, wherein the structure includes a movable electrode facing the fixed electrode, and a mirror coupled to the movable electrode, and the center of gravity of the movable electrode includes a plane including the movable electrode and the rotation axis of the structure The movable electrode and the mirror are spaced apart from each other in the direction along the rotational axis in the plane, and the center of gravity of the structure is on the rotational axis.

  The micromirror element further includes a pair of support members that are disposed along the rotation axis, are connected to the structure at opposite ends, and support the structure so as to be rotatable around the rotation axis. The center of gravity may be located at the midpoint between the pair of support members.

  In the micromirror element, the structure further includes a first balancer coupled to the mirror or the movable electrode, and the first balancer is separated from at least the movable electrode and the mirror along the rotation axis. May be.

  In the micromirror element, the structure further includes a second balancer coupled to any of the mirror, the movable electrode, and the first balancer, and the second balancer includes the coupled mirror and the movable electrode. The center of gravity of the second balancer is farther from the rotation axis than the center of gravity of any of the connected mirror, movable electrode, and balancer. You may make it exist in a distant position.

  In the micromirror element, at least a part of the balancer may be formed thicker than the mirror or the movable electrode.

  In the micromirror element, at least a part of the balancer may be formed of a material having a higher density than the material constituting the mirror or the movable electrode.

  In the micromirror element, the structure may be formed symmetrically with respect to an axis parallel to the substrate, passing through the center of gravity, and orthogonal to the rotation axis.

  Further, in the micromirror element, a second fixed electrode provided on the substrate, and a pair of support members, one end of which is connected to the structure, and rotatably supports the structure around the rotation axis. In addition, at least one of the support members may include a second movable electrode facing the second fixed electrode.

  The mirror array according to the present invention is a mirror array in which a plurality of micromirror elements are arranged one-dimensionally, and the micromirror elements are composed of the micromirror elements. Here, the micromirror elements may be arranged in a nested structure.

  According to the present invention, since the center of gravity of the movable electrode is separated from the rotation axis, a large rotation can be realized at a low voltage, so that a driver for applying a high voltage is not necessary, resulting in a low cost. it can. In addition, since the center of gravity of the structure is on the rotation axis, the structure can be prevented from rotating around the rotation axis even when subjected to disturbance, and as a result, stable rotation is realized. be able to.

FIG. 1 is a plan view schematically showing the configuration of the micromirror array according to the first embodiment of the present invention. 2 is a cross-sectional view taken along the line II of FIG. FIG. 3 is a plan view schematically showing the configuration of the mirror structure. FIG. 4 is a diagram illustrating measurement results of the drive characteristics of the micromirror array according to the first embodiment. FIG. 5 is a diagram illustrating a measurement result of a change with respect to the acceleration of the micromirror array according to the first embodiment. FIG. 6A is a diagram for explaining the method of manufacturing the electrode substrate in the first embodiment. FIG. 6B is a diagram for explaining the electrode substrate manufacturing method according to the first embodiment. FIG. 6C is a diagram for describing the electrode substrate manufacturing method according to the first embodiment. FIG. 6D is a diagram for explaining a method for manufacturing the electrode substrate according to the first embodiment. FIG. 6E is a view for explaining the method of manufacturing the electrode substrate in the first embodiment. FIG. 7A is a diagram for explaining the method of manufacturing the mirror substrate in the first embodiment. FIG. 7B is a diagram for explaining the manufacturing method of the mirror substrate according to the first embodiment. FIG. 7C is a diagram for describing the method of manufacturing the mirror substrate in the first embodiment. FIG. 7D is a diagram for explaining the method of manufacturing the mirror substrate in the first embodiment. FIG. 7E is a diagram for describing the method of manufacturing the mirror substrate in the first embodiment. FIG. 7F is a diagram for describing the method of manufacturing the mirror substrate in the first embodiment. FIG. 8 is a diagram for explaining a method of manufacturing the micromirror array according to the first embodiment. FIG. 9 is a perspective view schematically showing a modification of the movable electrode. FIG. 10 is an enlarged view of a main part of FIG. FIG. 11 is a plan view schematically showing the configuration of the mirror structure according to the second embodiment of the present invention. FIG. 12 is a plan view schematically showing the configuration of the mirror structure according to the third embodiment of the present invention. FIG. 13 is a plan view schematically showing the configuration of the mirror structure according to the fourth embodiment of the present invention. FIG. 14 is a plan view schematically showing the configuration of the mirror structure according to the fifth embodiment of the present invention. FIG. 15 is a plan view schematically showing the configuration of the mirror structure according to the sixth embodiment of the present invention. FIG. 16 is a plan view schematically showing the configuration of the mirror structure according to the seventh embodiment of the present invention. FIG. 17 is a plan view showing a modification of FIG. FIG. 18 is a diagram for explaining the configuration of a conventional mirror array. FIG. 19 is a diagram for explaining the configuration of a conventional mirror array.

[First Embodiment]
First, a first embodiment of the present invention will be described.

<Configuration of micromirror array>
As shown in FIGS. 1 and 2, the micromirror array according to the present embodiment includes an electrode substrate 1 composed of, for example, a silicon substrate, and is spaced apart from the electrode substrate 1 and faces the electrode substrate 1 substantially in parallel. And a mirror substrate 2 made of, for example, an SOI (Silicon-On-Insulator) substrate. For convenience, in the following, the direction along the plane of the electrode substrate 1 and the mirror substrate 2 is the “X-axis direction”, the direction along the plane and perpendicular to the X-axis direction is the “Y-axis direction”, the X-axis direction and the Y-axis. A direction orthogonal to the axial direction is referred to as a “Z-axis direction”.

  The electrode substrate 1 has an opening that is substantially rectangular in plan view, and a fixed electrode 3 is disposed on the bottom of the opening. The fixed electrode 3 is disposed at a position facing a movable electrode 53 of the mirror substrate 2 described later. A wiring is formed on the electrode substrate 1, and a voltage supplied from an external power source connected via the wiring is applied to the fixed electrode 3. The wiring may be formed so as to penetrate the electrode substrate 1.

  The mirror substrate 2 extends in the X-axis direction and is disposed in parallel with each other, and a plurality of mirror substrates 2 arranged in the X-axis direction between the pair of base portions 4 and 4 ′. The mirror structure 5 and a pair of support members 6, 6 ′ provided for each mirror structure 5, extending in the Y-axis direction and connecting the base 4 and the mirror structure 5.

  In the present embodiment, a micromirror element is configured by the fixed electrode 3 and the mirror structure 5, and the micromirror array is configured by arranging the micromirror elements in the X-axis direction.

  Here, as shown in FIG. 3, the mirror structure 5 is connected to a mirror 51 connected to one base 4 via a support member 6 and to the other base 4 ′ via a support member 6 ′. A balancer member 52 and a movable electrode 53 connected to the mirror 51 and the balancer member 52 through a pair of connecting members 54 and 54 'are provided. As described above, the mirror structure 5 is supported by the support members 6 and 6 ′ so as to be rotatable around an axis (rotation axis) α parallel to the Y axis connecting them. Further, the mirror 51, the balancer member 52, and the movable electrode 53 are separated from each other in the Y-axis direction.

  The mirror 51 is formed in a substantially rectangular shape in plan view, and each side is arranged in parallel to the X axis or the Y axis. The support member 6 is connected to the end of one side in the X-axis direction (hereinafter referred to as “negative side”) of each side of the mirror 51 facing the base 4. ing. In addition, one end of the connecting member 54 is connected to the side facing the base 4 ′ at the end on the negative side in the X-axis direction. Since one end of the connecting member 54 is located on the rotation axis α, the rotation axis α is in the vicinity of the side on the negative side in the X-axis direction among the sides parallel to the Y-axis direction of the mirror 51. Will pass. For this reason, since the mirror 51 is located on the positive side in the X axis direction with respect to the rotation axis α as a whole, the center of gravity of the mirror 51 is also on the positive side in the X axis direction with respect to the rotation axis α. Will be located. A reflective film is formed on the upper surface of the mirror 51.

  The balancer member 52 is formed in a substantially rectangular shape in plan view having the same size as the mirror 51, and each side is arranged in parallel to the X axis or the Y axis. Of each side of the balancer member 52, the side opposite to the base 4 'is connected to a support member 6' at the negative end in the X-axis direction. Further, one end of the connecting member 54 ′ is connected to the side facing the base portion 4 at the negative end in the X-axis direction. Since one end of the connecting member 54 ′ is located on the rotation axis α, the rotation axis α is a side on the negative side in the X-axis direction among the sides parallel to the Y-axis direction of the balancer member 52. It will pass through the neighborhood. For this reason, since the balancer member 52 is located on the positive side in the X-axis direction with respect to the rotation axis α as a whole, the center of gravity of the balance member 52 is also positive in the X-axis direction with respect to the rotation axis α. It will be located on the side. Note that a material equivalent to the reflective film formed on the mirror 51 is disposed on the upper surface of the balancer member 52.

  The movable electrode 53 is formed in a substantially rectangular shape in plan view having an area that is approximately equal to the connection between the mirror 51 and the balancer member 52, and each side is arranged in parallel to the X axis or the Y axis. Among the sides of the movable electrode 53, the side facing the base 4 is connected to the other end of the connecting member 54 that extends from one end connected to the mirror 51 to the negative side in the X-axis direction. Yes. Further, the other end of the connecting member 54 ′ extending from one end connected to the balancer member 52 to the negative side in the X-axis direction is connected to the side facing the base portion 4 ′. Therefore, since the movable electrode 53 is located on the negative side in the X-axis direction with respect to the rotation axis α, the center of gravity of the movable electrode 53 is also rotated within the plane including the movable electrode 53 and the rotation axis α. It is located at a location spaced from the moving axis α to the negative side in the X-axis direction.

  As described above, the mirror structure 5 has the mirror 51 and the balancer member 52 on the positive side in the X-axis direction with respect to the rotation axis α, and the movable electrode 53 having the total area of the mirror 51 and the balancer member 52 X The center of gravity is set so as to be positioned on the rotation axis α by being positioned on the negative side in the axial direction and balancing the weight of each member across the rotation axis α. The center of gravity is set so as to be positioned at the center between the connection ends of the support members 6 and 6 ′ and the mirror 51 or the balancer member 52. As described above, since the center of gravity G of the mirror structure 5 is on the midpoint of the rotation axis α, the mirror structure 5 can be rotated evenly by the rotation axes α and β (rotation parallel to the Z axis passing through the center of gravity). Axis) and γ (rotation axis parallel to the X axis passing through the center of gravity) can be prevented, and as a result, fluctuations in optical power can be prevented.

  In the mirror structure 5, the mirror 51, the balancer member 52, and the movable electrode 53 are separated in the Y-axis direction. As a result, when the mirror structures 5 are arranged in the X-axis direction to form a mirror array, it is possible to arrange the mirror structures 5 in a so-called nested structure. Can be arranged in density. Therefore, the fill factor of the mirror 51 can be improved.

  In this embodiment, the center of gravity of the mirror structure 5 is a straight line (rotation axis α) connecting the connection end between the mirror 51 and the support member 6 and the connection end between the balancer member 52 and the support member 6 ′. Located at the midpoint. Further, the mirror structure 5 is formed in line symmetry with respect to a straight line passing through the midpoint and parallel to the X-axis direction.

<Operation of micromirror array>
Next, the operation of the micromirror array according to the present embodiment will be described.

  First, when no voltage is applied to the fixed electrode 3, the mirror structure 5 is supported by the support members 6 and 6 ′, and the mirror 51, the balancer member 52, and the movable electrode 53 are connected to the electrode substrate 1 and the mirror substrate 2. It is in the state located in the same plane parallel to.

  When a voltage is applied to the fixed electrode 3 from this state, the mirror structure 5 has a negative electrode in the Z-axis direction. Is displaced around the rotation axis α. At this time, the movable electrode 53 is disposed at a position away from the rotation axis α. Therefore, even if the electrostatic attractive force is small, a large torque can be obtained, so that the mirror structure 5 can be largely rotated at a low voltage. As described above, since a large rotation can be realized at a low voltage, a special driver or the like is not necessary, and as a result, a reduction in cost can be realized.

  When the application of voltage to the fixed electrode 3 is stopped from the state in which the fixed electrode 3 is displaced downward, the mirror structure 5 loses the electrostatic attraction generated by the fixed electrode 3, so that the support members 6 and 6 ′ The mirror 51, the balancer member 52, and the movable electrode 53 are returned to a state in which they are located in the same plane parallel to the electrode substrate 1 and the mirror substrate 2 due to the torsional force received around the rotation axis α.

  Measurements were made with respect to changes in drive characteristics and acceleration in the micromirror array according to the present embodiment. The measurement results are shown in FIGS. The measurement results shown in FIGS. 4 and 5 relate to the mirror structure 5 shown in FIG. The dimensions of each part of the mirror structure 5 at this time are as follows. The mirror 51 and the balancer member 52 have lengths of 100 [μm] in the X-axis direction and the Y-axis direction, respectively. The movable electrode 53 has a length in the X-axis direction of 100 [μm] and a length in the Y-axis direction of 200 [μm]. The connecting members 54 and 54 'have a length in the Y-axis direction of 43 [μm].

  As shown in FIG. 4, in the present embodiment, the voltage applied to the fixed electrode 3 to achieve a rotation angle of 4 [deg] was 20 [V]. As described above, in this embodiment, it was confirmed that the mirror structure 5 can be largely rotated at a low voltage by disposing the movable electrode 53 at a position away from the rotation axis α.

  Further, as shown in FIG. 5, in the present embodiment, even when an acceleration of 20 [g] was applied, the rotation angle was not changed. As described above, in this embodiment, the center of gravity of the mirror structure 5 is positioned on the rotation axis α to prevent the mirror structure 5 from rotating about the rotation axis α even when subjected to a disturbance. It was confirmed that

<Manufacturing method of micromirror array>
Next, with reference to FIGS. 6A to 8, a method for manufacturing the micromirror array according to the present embodiment will be described.

  First, as shown in FIG. 6A, a silicon substrate 101 made of, for example, a silicon single crystal is prepared. Next, as shown in FIG. 6B, a resist pattern 102 is formed on the silicon substrate. The resist pattern 102 may be formed by a known photolithography technique.

  Next, as shown in FIG. 6C, the silicon substrate 101 is selectively etched by known dry etching using the resist pattern 102 as a mask to form an opening having a substantially rectangular shape in plan view. Next, after removing the resist pattern 102 as shown in FIG. 6D, the fixed electrode 3 is formed on the bottom surface of the opening formed in the silicon substrate 101 as shown in FIG. 6E. For example, the fixed electrode 3 can be formed by depositing a metal by sputtering or the like. Alternatively, the fixed electrode 3 may be formed by depositing metal by a plating method or the like. The electrode substrate 1 is produced | generated by the above process.

  Next, as shown in FIG. 7A, an SOI (Silicon on Insulator) substrate 111 is prepared. The SOI substrate 111 is a substrate in which a surface silicon layer 114 is formed on a silicon base 112 via a buried insulating layer 113.

  Next, as shown in FIG. 7B, a resist pattern 115 corresponding to the planar shapes of the bases 4, 4 ′, the mirror structure 5, and the support members 6, 6 ′ is formed on the silicon substrate on the surface silicon layer 114. . The resist pattern 115 may be formed by a known photolithography technique.

  Next, as shown in FIG. 7C, the surface silicon layer 114 is selectively etched by known dry etching or the like using the resist pattern 115 as a mask, and then the resist pattern 115 is removed as shown in FIG. 7D.

  Next, as shown in FIG. 7E, the silicon base 112 and the buried insulating layer 113 are selectively etched and removed to form the bases 4 and 4 ′, the mirror structure 5 and the support members 6 and 6 ′. .

  Next, as illustrated in FIG. 7F, a reflective film 116 is formed on the surfaces of the mirror 51 and the balancer member 52 of the mirror structure 5. For example, the reflective film 116 can be formed by depositing a metal such as gold by sputtering. Alternatively, the reflective film 116 may be formed by depositing a metal such as gold by a plating method, a resistance heating vapor deposition method, or the like. The mirror substrate 2 is generated by the above process.

  Next, as shown in FIG. 8, the surface of the mirror substrate 2 on the surface silicon layer 114 side is formed on the surface on which the electrode substrate 1 and the mirror substrate 2 generated by the above-described steps are formed. Paste together. As a result, the micromirror array according to the present embodiment is generated.

  As described above, according to the present embodiment, since the center of gravity of the movable electrode 53 is separated from the rotation axis α, a large rotation can be realized at a low voltage, and a driver for applying a high voltage, etc. As a result, low cost can be realized. Further, since the center of gravity of the mirror structure 5 is on the rotation axis α, the mirror structure 5 can be prevented from rotating around the rotation axis α even when subjected to a disturbance, and as a result, stable. Rotation can be realized.

In the present embodiment, the case where a flat electrode is used as the movable electrode 53 has been described as an example. However, as shown in FIG. 9, the movable electrode 53 extends from the rod-shaped first beam member 531 in the same direction. You may make it comprise what is called a comb-shaped movable electrode 53 'provided with the several 2nd beam member 532 which protruded. At this time, the fixed electrode 3 has a configuration in which plate-like electrode members 3 ′ are arranged in parallel with each other with a predetermined distance therebetween. Also by adopting such a configuration, it is possible to achieve the same operational effects as the operational effects of the present embodiment described above.
As shown in FIG. 10, the shape of the second beam member 532 of the fixed electrode 3 and the movable electrode 53 ′ is such that the width in the Y-axis direction is 4 [μm] and the length in the X-axis direction is 80 [μm]. In addition, by providing 15 second beam members 532, the characteristics shown in FIGS. 4 and 5 could be obtained.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment described above in the configuration of the fixed electrode 3 and the mirror structure 5. Therefore, in this embodiment, the same name and code | symbol are attached | subjected about the structure equivalent to 1st Embodiment mentioned above, and description is abbreviate | omitted suitably.

  As shown in FIG. 11, the mirror structure 5a in the present embodiment is supported by a mirror 51a supported by one end of a pair of connecting members 54a and 54a ', and the other end of the connecting member 54a and one end of the connecting member 55a. And a second movable electrode 53a ′ supported by the other end of the connecting member 54a ′ and one end of the connecting member 55a ′. Here, the support member 6 is connected to the other end of the connecting member 55a. Similarly, the support member 6 'is connected to the other end of the connection member 55a'. Accordingly, the mirror structure 5a is supported by the support members 6 and 6 'so as to be rotatable about an axis (rotation axis α) parallel to the Y axis connecting them. In addition, the mirror 51a, the first movable electrode 53a, and the second movable electrode 53a 'are separated in the Y-axis direction. Further, on the electrode substrate, the fixed electrode 3a is disposed at a position facing the first movable electrode 53a, and the fixed electrode 3a 'is disposed at a position facing the second movable electrode 53a.

  Here, the mirror 51a is formed in a substantially rectangular shape in plan view, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X axis of the mirror 51a, one end of the connecting member 54a is connected to the side on the positive side in the Y axis direction at the end on the negative side in the X axis direction. One end of the connecting member 54a ′ is connected to the negative side edge of the negative electrode in the X-axis direction. The connecting members 54a and 54a 'extend from one end connected to the mirror 51a to the negative side in the X-axis direction to the position passing through the rotation axis α. Therefore, the rotation axis α is located on the negative side in the X-axis direction with respect to the mirror 51a. Thus, since the mirror 51a as a whole is located on the positive side in the X-axis direction with respect to the rotation axis α, the center of gravity of the mirror 51 is also positive in the X-axis direction with respect to the rotation axis α. Will be located on the side.

  The first movable electrode 53a is formed in a substantially rectangular shape in plan view having the same size as the mirror 51a, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X axis of the first movable electrode 53a, the negative side in the Y axis direction has one end connected to the end on the positive side in the X axis direction and the mirror 51a. The other end of the connecting member 54a is connected. Further, one end of the connecting member 55a 'is connected to the positive side edge in the X-axis direction on the positive side edge in the Y-axis direction. The connecting member 55 a extends from one end to the positive side in the X-axis direction, and the other end is connected to the support member 6. Therefore, the rotation axis α is located on the positive side in the X-axis direction with respect to the first movable electrode 53a. Thus, since the first movable electrode 53a is located on the negative side in the X-axis direction with respect to the rotation axis α as a whole, the center of gravity of the first movable electrode 53a is also on the rotation axis α. On the other hand, it is located on the negative side in the X-axis direction. Such a first movable electrode 53 a functions as the balancer member 52 and the movable electrode 53 in the first embodiment.

  The second movable electrode 53a 'is formed in a substantially rectangular shape in plan view having the same size as the mirror 51a, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X axis of the second movable electrode 53a ′, the side on the positive side in the Y axis direction is connected to the end on the positive side in the X axis direction, and one end is connected to the mirror 51a. The other end of the connected member 54a 'is connected. Further, one end of the connecting member 55a 'is connected to the negative side edge in the Y-axis direction at the positive side end in the X-axis direction. The connecting member 55a 'extends from one end to the positive side in the X-axis direction, and the other end is connected to the support member 6'. Therefore, the rotation axis α is positioned on the positive side in the X-axis direction with respect to the second movable electrode 53a ′. Thus, since the second movable electrode 53a ′ is located on the negative side in the X-axis direction with respect to the rotation axis α as a whole, the center of gravity of the second movable electrode 53a ′ is also the rotation axis α. Is located on the negative side in the X-axis direction. Such a second movable electrode 53 a ′ functions as the balancer member 52 and the movable electrode 53 in the first embodiment.

  As described above, the mirror structure 5a has the mirror 51a on the positive side in the X-axis direction and the first movable electrode 53a and the second movable electrode 53a ′ on the negative side in the X-axis direction with respect to the rotation axis α. The center of gravity G is set on the rotation axis α by balancing the weight of each member with the rotation axis α interposed therebetween. As described above, since the center of gravity G of the mirror structure 5a is on the rotation axis α, it is possible to prevent the mirror structure 5a from rotating about the rotation axis α even when subjected to a disturbance. Optical power fluctuation can be prevented.

  In the mirror structure 5a, the mirror 51a, the first movable electrode 53a, and the second movable electrode 53a 'are separated in the Y-axis direction. As a result, when the mirror structures 5a are arranged in the X-axis direction to form a mirror array, it is possible to arrange the mirror structures 5a in a so-called nested structure. Can be arranged in density. Therefore, the fill factor of the mirror 51a can be improved.

  Further, the first movable electrode 53a and the second movable electrode 53a 'are arranged at positions away from the rotation axis α. Therefore, even if the electrostatic attractive force is small, a large torque can be obtained, so that the mirror structure 5a can be largely rotated at a low voltage. As described above, since a large rotation can be realized at a low voltage, a special driver or the like is not necessary, and as a result, a reduction in cost can be realized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. This embodiment is different from the first embodiment described above in the configuration of the fixed electrode 3 and the mirror structure 5. Therefore, in this embodiment, the same name and code | symbol are attached | subjected about the structure equivalent to 1st Embodiment mentioned above, and description is abbreviate | omitted suitably.

  As shown in FIG. 12, the mirror structure 5b in the present embodiment includes a mirror 51b supported by one end of a pair of connecting members 54b and 54b ′ and a first movable member supported by the other end of the connecting member 54b. An electrode 53b and a second movable electrode 53b ′ supported by the other end of the connecting member 54b ′ are provided. Here, the supporting member 6 is connected to one end side of the connecting member 54b. Similarly, the support member 6 'is connected to one end side of the connection member 54b'. Therefore, the mirror structure 5b is supported by the support members 6 and 6 'so as to be rotatable about an axis (rotation axis α) parallel to the Y axis connecting them. Further, the mirror 51b, the first movable electrode 53b, and the second movable electrode 53b 'are separated in the Y-axis direction. Further, on the electrode substrate, the fixed electrode 3b is disposed at a position facing the first movable electrode 53b, and the fixed electrode 3b 'is disposed at a position facing the second movable electrode 53b'.

  Here, the mirror 51b is formed in a substantially rectangular shape in plan view, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X axis of the mirror 51b, one end of the connecting member 54b is connected to the side on the positive side in the Y axis direction at the end on the negative side in the X axis direction. One end of the connecting member 54b ′ is connected to the negative side edge of the negative end in the X-axis direction. The support member 6 or the support member 6 ′ is connected to the ends of the coupling members 54 b and 54 b ′ connected to the mirror 51 b. Therefore, the rotation axis α passes through the vicinity of the negative side in the X-axis direction among the sides parallel to the Y-axis direction of the mirror 51b. For this reason, since the mirror 51b is positioned on the positive side in the X-axis direction with respect to the rotation axis α as a whole, the center of gravity G of the mirror 51b is also positive in the X-axis direction with respect to the rotation axis α. Will be located on the side.

  The first movable electrode 53b is formed in a substantially rectangular shape in plan view having the same size as the mirror 51b, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X axis of the first movable electrode 53b, the side on the negative side in the Y axis direction is connected to the end on the positive side in the X axis direction, and one end is connected to the mirror 51b. The other end of the connecting member 54b extending to the negative side in the X-axis direction is connected. Therefore, the rotation axis α is located on the positive side in the X-axis direction with respect to the first movable electrode 53b. Thus, since the first movable electrode 53b is located on the negative side in the X-axis direction with respect to the rotation axis α as a whole, the center of gravity of the first movable electrode 53b is also on the rotation axis α. On the other hand, it is located on the negative side in the X-axis direction. Such a first movable electrode 53b functions as the balancer member 52 and the movable electrode 53 in the first embodiment.

  The second movable electrode 53b 'is formed in a substantially rectangular shape in plan view having the same size as the mirror 51b, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X axis of the second movable electrode 53b, the side on the positive side in the Y axis direction is connected to the end on the positive side in the X axis direction, and one end is connected to the mirror 51b. The other end of the connecting member 54b ′ extending to the negative side in the X-axis direction is connected. Therefore, the rotation axis α is located on the positive side in the X-axis direction with respect to the second movable electrode 53b ′. Thus, since the second movable electrode 53b ′ is located on the negative side in the X-axis direction with respect to the rotation axis α as a whole, the center of gravity of the second movable electrode 53b ′ is also the rotation axis α. Is located on the negative side in the X-axis direction. Such a second movable electrode 53 b ′ functions as the balancer member 52 and the movable electrode 53 in the first embodiment.

  As described above, the mirror structure 5b has the mirror 51b on the positive side in the X-axis direction and the first movable electrode 53b and the second movable electrode 53b ′ on the negative side in the X-axis direction with respect to the rotation axis α. The center of gravity G is set on the rotation axis α by balancing the weight of each member with the rotation axis α interposed therebetween. Further, the center of gravity is set so as to be positioned at the center between the connection ends of the support members 6 and 6 ′ and the connecting members 54 b and 54 b ′. As described above, since the center of gravity G of the mirror structure 5 is on the midpoint of the rotation axis α, the mirror structure 5 can be rotated evenly by the rotation axes α and β (rotation parallel to the Z axis passing through the center of gravity). Axis) and γ (rotation axis parallel to the X axis passing through the center of gravity) can be prevented, and as a result, fluctuations in optical power can be prevented.

  In the mirror structure 5b, the mirror 51b, the first movable electrode 53b, and the second movable electrode 53b 'are separated in the Y-axis direction. Accordingly, when the mirror structure 5b is arranged in the X-axis direction to form a mirror array, it is possible to arrange the mirror structures 5b in a so-called nested structure, so that the mirror structures 5b are close to each other without interfering with the components of the adjacent mirror structure 5b. Can be arranged in density. Therefore, the fill factor of the mirror 51b can be improved.

  Further, the first movable electrode 53b and the second movable electrode 53b 'are disposed at positions away from the rotation axis α. Therefore, even if the electrostatic attractive force is small, a large torque can be obtained, so that the mirror structure 5b can be largely rotated at a low voltage. As described above, since a large rotation can be realized at a low voltage, a special driver or the like is not necessary, and as a result, a reduction in cost can be realized.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. In the present embodiment, movable electrodes are further provided on the support members 6 and 6 'in the first embodiment described above. Therefore, in this embodiment, the same name and code | symbol are attached | subjected about the structure equivalent to 1st Embodiment mentioned above, and description is abbreviate | omitted suitably.

  As shown in FIG. 13, a mirror 51 connected to one base 4 via a mirror structure 5c and a support member 6c, and a balancer member 52 connected to the other base 4 ′ via a support member 6c ′. And a movable electrode 53 connected to the mirror 51 and the balancer member 52 through a pair of connecting members 54 and 54 '. Thus, the mirror structure 5 is supported by the support members 6c and 6c 'so as to be rotatable around an axis (rotation axis α) parallel to the Y axis connecting them. Further, the mirror 51, the balancer member 52, and the movable electrode 53 are separated from each other in the Y-axis direction. Such a mirror structure 5c is formed so that the center of gravity G is on the rotation axis α.

  Here, the support member 6c includes a first beam member 61 having one end connected to the mirror 51, a third movable electrode 62 to which the other end of the first beam member 61 is connected, and a third end having a third end. The second beam member 63 is connected to the movable electrode 62 and the other end is connected to the base 4. Here, the fixed electrode 3 c is disposed on the upper surface of the electrode substrate 1 at a position facing the third movable electrode 62.

  Similarly, the support member 6d ′ includes a first beam member 61 ′ having one end connected to the balancer member 52, and a third movable electrode 62 ′ having the other end connected to the first beam member 61 ′. The second beam member 63 ′ has one end connected to the third movable electrode 62 ′ and the other end connected to the base 4 ′. Here, a fixed electrode 3 c ′ is disposed on the upper surface of the electrode substrate 1 at a position facing the third movable electrode 62 ′.

  In the present embodiment, when a voltage is applied to the fixed electrodes 3c and 3c ′, the third movable electrodes 62 and 62 ′ disposed so as to face the fixed electrodes 3c and 3c ′ are fixed by the electrostatic attraction generated. Attracted to 3c, 3c ′. Therefore, for example, the mirror structure 3c can be rotated around the X axis by applying a voltage to one of the fixed electrodes 3c and 3c ′ or alternately applying a voltage to the fixed electrodes 3c and 3c ′. .

  Needless to say, in this embodiment, the same effects as those described in the first embodiment can be obtained.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. In the present embodiment, the support members 6 and 6 ′ in the third embodiment described above are further provided with a configuration equivalent to the movable electrodes 6c and 6c ′ in the fourth embodiment. Therefore, in this embodiment, the same name and code | symbol are attached | subjected about the structure equivalent to 3rd Embodiment mentioned above, and description is abbreviate | omitted suitably.

  As shown in FIG. 14, the mirror structure 5d in the present embodiment includes a mirror 51b supported by one end of a pair of connecting members 54b and 54b ′, and a first movable member supported by the other end of the connecting member 54b. An electrode 53b and a second movable electrode 53b ′ supported by the other end of the connecting member 54b ′ are provided. Here, the supporting member 6d is connected to one end side of the connecting member 54b. Similarly, a support member 6d 'is connected to one end side of the connection member 54b'. Accordingly, the mirror structure 5b is supported by the support members 6d and 6d 'so as to be rotatable about an axis (rotation axis α) parallel to the Y axis connecting them. Further, the mirror 51b, the first movable electrode 53b, and the second movable electrode 53b 'are separated in the Y-axis direction. On the electrode substrate, the fixed electrode 3b is disposed at a position facing the first movable electrode 53b, and the fixed electrode 3b 'is disposed at a position facing the second movable electrode 53b'. Further, such a mirror structure 5d is formed such that the center of gravity G is on the midpoint of the rotation axis α.

  Here, the supporting member 6d includes a first beam member 61 having one end connected to the connecting member 54b, a third movable electrode 62 to which the other end of the first beam member 61 is connected, and one end being a first member. 3 and a second beam member 63 connected to the base 4 at the other end. Here, a fixed electrode 3 d is disposed on the upper surface of the electrode substrate 1 at a position facing the third movable electrode 62.

  Similarly, the support member 6d ′ includes a first beam member 61 ′ having one end connected to the coupling member 54b ′ and a third movable electrode 62 ′ to which the other end of the first beam member 61 ′ is connected. And a second beam member 63 ′ having one end connected to the third movable electrode 62 ′ and the other end connected to the base 4 ′. Here, a fixed electrode 3d 'is disposed on the upper surface of the electrode substrate 1 at a position facing the third movable electrode 62'.

  In the present embodiment, when a voltage is applied to the fixed electrodes 3d and 3d ′, the third movable electrodes 62 and 62 ′ disposed to face the fixed electrodes 3d and 3d ′ are fixed to the fixed electrodes by the electrostatic attraction generated. It is attracted to 3d and 3d ′. Therefore, for example, the mirror structure 3d can be rotated around the X axis by applying a voltage to one of the fixed electrodes 3d and 3d ′ or alternately applying a voltage to the fixed electrodes 3d and 3d ′. .

  Needless to say, in this embodiment, the same effects as those described in the third embodiment can be obtained.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. In the present embodiment, a balancer member 52 is further provided in the first embodiment described above. Therefore, in this embodiment, the same name and code | symbol are attached | subjected about the structure equivalent to 1st Embodiment mentioned above, and description is abbreviate | omitted suitably.

  As shown in FIG. 15, the mirror structure 5e includes a mirror 51 connected to one base 4 via a support member 6, and a balancer member 52 connected to the other base 4 ′ via a support member 6 ′. A movable electrode 53 coupled to the mirror 51 and the balancer member 52 via a pair of coupling members 54, 54 ', a second balancer member 56 coupled to the mirror 51 via a coupling member 57, and a coupling member And a second balancer member 56 ′ connected to the balancer member 52 through 57 ′. In this way, the mirror structure 5e is supported by the support members 6 and 6 'so as to be rotatable about an axis (rotation axis α) parallel to the Y axis connecting them. Further, the mirror 51, the balancer member 52, and the movable electrode 53 are separated from each other in the Y-axis direction. Further, such a mirror structure 5e is formed so that the center of gravity G is on the midpoint of the rotation axis α.

  Here, the second balancer member 56 is formed in a substantially rectangular shape in plan view, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X axis of the second balancer member 56, one end of the connecting member 57 is connected to the negative side end in the X axis direction at the negative side end in the X axis direction. ing. The other end of the connecting member 57 is connected to an end on the positive side in the X-axis direction of the side opposite to the side to which the connecting member 54 of the mirror 51 is connected.

  The second balancer member 56 'is formed in a substantially rectangular shape in plan view, and each side is arranged in parallel to the X axis or the Y axis. Of the sides parallel to the X-axis of the second balancer member 56 ′, the side on the positive side in the Y-axis direction has one end of the connecting member 57 ′ at the end on the negative side in the X-axis direction. It is connected. The other end of the connecting member 57 'is connected to the positive end in the X-axis direction of the side opposite to the side to which the connecting member 54' of the balancer member 52 is connected.

  As described above, the mirror structure 5e is provided with the second balancer members 57 and 57 ′ in addition to the mirror 51, the balancer member 52, and the movable electrode 53, and balances the weight of each member across the rotation axis α. Since the center of gravity G is positioned on the rotation axis α, the movable electrode 53 is further separated from the rotation axis α. Thereby, since a larger torque can be obtained, the mirror structure 5e can be largely rotated at a lower voltage.

  Needless to say, in this embodiment, the same effects as those described in the first embodiment can be obtained.

[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described. Note that the present embodiment is different from the first embodiment described above in the configuration of the balancer member 52. Therefore, in this embodiment, the same name and code | symbol are attached | subjected about the structure equivalent to 1st Embodiment mentioned above, and description is abbreviate | omitted suitably.

  As shown in FIG. 16, the mirror structure 5f includes a mirror 51 connected to one base portion 4 via a support member 6, and a balancer member 52f connected to the other base portion 4 'via a support member 6'. And a movable electrode 53 connected to the mirror 51 and the balancer member 52 through a pair of connecting members 54 and 54 '. Thus, the mirror structure 5f is supported by the support members 6 and 6 'so as to be rotatable around an axis (rotation axis α) parallel to the Y axis connecting them. Further, the mirror 51, the balancer member 52, and the movable electrode 53 are separated from each other in the Y-axis direction. Further, such a mirror structure 5e is formed so that the center of gravity G is on the rotation axis α.

  Here, the balancer member 52f has a smaller area as compared with the mirror 51, but has a larger thickness, that is, a length in the Z-axis direction. Thus, by increasing the thickness and increasing the mass, the center of gravity G of the mirror structure 5f can be positioned on the rotation axis α even if the area of the balancer member 52f is reduced. Thereby, since the mirror structure 5f can be reduced in size, the mirror array can also be reduced in size.

  Note that, as a balancer member 52f 'shown in FIG. 17, a different material may be used to make it different from the thickness mirror 51 or the like. In the balancer member 52 f ′, a high-density material 522 such as gold is disposed on the silicon 521. Thereby, the mirror structure 5f can be further downsized.

  The present invention can be applied to various actuators manufactured by micromachine technology, such as a MEMS mirror device.

  DESCRIPTION OF SYMBOLS 1 ... Electrode substrate, 2 ... Mirror substrate, 3, 3b, 3b ', 3c, 3c' ... Fixed electrode, 4, 4 '... Base part, 5, 5a, 5b, 5c, 5d, 5e, 5f, 5g ... Mirror structure Body, 6, 6 ', 6c, 6c', 6d, 6d '... support member, 51, 51a, 51b ... mirror, 52 ... balancer member, 53 ... movable electrode, 53a ... first movable electrode, 53a', 53b 53b ′, second movable electrode, 54, 54 ′, 54a, 54a ′, 54b, 54b ′, 55a, 55a ′, 57, 57 ′, connection member, 56, 56 ′, second balancer member, 61 ... 1st beam member, 62 ... 3rd movable electrode, 63 ... 2nd beam member, 101 ... Silicon substrate, 102 ... Resist pattern, 111 ... SOI substrate, 112 ... Silicon base, 113 ... Embedded insulating layer, 114 ... Surface silicon layer, 115 ... Strike pattern, 116 ... reflective layer, 521 ... silicon, 522 ... materials, G ... centroid, alpha ... rotation axis alpha.

Claims (10)

A micromirror device comprising a fixed electrode provided on a substrate and a structure disposed so as to be rotatable away from the substrate,
The structure includes a movable electrode facing the fixed electrode, and a mirror connected to the movable electrode,
The center of gravity of the movable electrode is separated from the rotation axis in a plane including the movable electrode and the rotation axis of the structure,
The movable electrode and the mirror are separated in a direction along the rotation axis in the plane,
The micromirror element, wherein the center of gravity of the structure is on the rotation axis. The micromirror element according to claim 1, wherein
A pair of support members disposed along the rotation axis and having opposite ends connected to the structure and supporting the structure so as to be rotatable about the rotation axis;
The center of gravity is located at a midpoint between the pair of support members. The micromirror element according to claim 1 or 2,
The structure further includes a first balancer connected to the mirror or the movable electrode,
The micro-mirror element, wherein the first balancer is separated from at least the movable electrode and the mirror along the rotation axis. In the micromirror element according to claim 3,
The structure further includes a second balancer coupled to any of the mirror, the movable electrode, and the first balancer,
The second balancer is at a position farther from the center of gravity of the structure than any of the mirror, the movable electrode, and the first balancer connected to each other.
The center of gravity of the second balancer is at a position farther from the rotation shaft than the center of gravity of any of the mirror, the movable electrode, and the balancer connected to each other. The micromirror element according to claim 3 or 4,
At least a part of the balancer is formed thicker than the mirror or the movable electrode. The micromirror element according to any one of claims 3 and 4,
At least a part of the balancer is formed of a material having a higher density than a material constituting the mirror or the movable electrode. The micromirror element according to any one of claims 1 to 6,
The micromirror element, wherein the structure is formed in parallel with the substrate, passes through the center of gravity, and is symmetrical with respect to an axis orthogonal to the rotation axis. In the micromirror element according to any one of claims 1 to 7,
A second fixed electrode provided on the substrate;
At least one of the support members includes a second movable electrode facing the second fixed electrode. A micromirror element, wherein: A mirror array in which a plurality of micromirror elements are arranged one-dimensionally,
The said micromirror element consists of a micromirror element of any one of Claims 1 thru | or 8. The mirror array characterized by the above-mentioned. The mirror array according to claim 9, wherein
The micromirror elements are arranged in a nested structure.

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