JP4559744B2 - Comb-shaped actuator and light control element - Google Patents

Description

  The present invention relates to a comb-shaped actuator and a light control element.

  In optical fiber communication, mirrors and filters that reflect or semi-transmit light are used for optical resonators, optical switches, and optical attenuators. The diameter of the collimator light beam entering and exiting the optical fiber is a minute diameter of about 1 mm or less. However, if a mirror itself or a mechanism for rotating or moving the mirror is added to the collimator light, a large-scale device for the minute light flux Therefore, downsizing is required.

  As a miniaturized structure, a movable electrode having comb-shaped electrode fingers that move by electrostatic attraction on the periphery of a small-area mirror was applied between both electrodes in the same manner as a fixed electrode having comb-shaped electrode fingers. Comb-shaped actuators have been developed that drive movable electrodes with electrostatic force generated by voltage.

  FIG. 11 illustrates a comb-shaped actuator. A movable electrode 101 having a rectangular shape has a group of comb-shaped movable electrode fingers 102a and 102b arranged on two opposing sides thereof, and a pair of fixed electrodes are opposed to these. Electrodes 110 and 111 are provided in pairs. Comb-shaped fixed electrode finger groups 113a and 113b are provided on the side of the fixed electrode with respect to the movable electrode, and the electrode fingers of both electrodes are arranged in an interlaced manner. Opposite the other opposite sides 104 and 105 of the movable electrode 101, fixed portions 121 and 122 that serve as connection terminals of the movable electrode are arranged at a distance from the movable electrode, and the movable electrode 101 is fixed at the center of the opposite sides 104 and 105. Suspensions 106 and 107 that are connected to and suspended from the sections 121 and 122 are provided.

As shown in FIG. 12, the movable electrode finger 102 of the movable electrode 101 and the fixed electrode finger 113 of the fixed electrode 110 (111) are arranged in an intricate manner, and the movable electrode fingers 113 ₁ and 113 ₂ are adjacent to each other. gap region 131 ₁ equally spaced g0 the electrode fingers 102, 131 ₂ is set to. As shown in FIGS. 13 and 14, when the length of each electrode finger is 1, the height is h (hi, h2), and the width is w, the upper fixed electrode fingers 113 ₁ , 113 If the movable electrode fingers 102 is configured positioned lower relative to the _2, suction force F upward by the respective electrode fingers electrostatic E occurs by applying a voltage between the electrodes. Further, when both electrode fingers 102, 113 ₁ and 113 ₂ are arranged on the same plane as shown in FIG. 13B, the height of each electrode finger is changed, for example, the height of the fixed electrode finger is h1 and is movable. By setting the height of the electrode finger 102 to h2, a suction force F in the height direction is generated. As shown in FIG. 11, the movable electrode 101 rotates as indicated by reference numeral 108 with the suspensions 106 and 107 as axes.

However, if the electrostatic force generated in the gap region between the fixed electrode fingers 113 ₁ and 113 ₂ and the movable electrode finger 102 shown in FIG. 12 does not work equally on the left and right, one fixed electrode finger side, for example, 113 _{1 with} respect to the movable electrode finger. A strong suction force works. Even if the manufacturing error of the electrode is slight, the electrostatic force tends to be biased. When this biased electrostatic force is generated, the entire electrode finger group is rotated within the movable electrode surface as indicated by reference numeral 109a in FIG. An electrostatic force biased in the direction is generated, and the fixed electrode and the movable electrode do not come into contact with each other, and the required rotation control is hindered.

  The present invention provides an electrostatic actuator that prevents contact between a movable electrode and a fixed electrode due to such an unfavorable attractive force. Moreover, the electrostatic actuator which eliminates the instability of the electrostatic force accompanying the dimensional shape error of the electrode finger due to manufacture is obtained.

One aspect of the present invention is a fixed electrode having a conductive fixed electrode base and a fixed electrode finger group including a plurality of fixed electrode fingers arranged in a comb-like shape over a predetermined length on at least one side of the fixed electrode base. Electrodes,
A conductive movable electrode base, and a movable electrode finger group including a plurality of movable electrode fingers arranged in a comb-like shape over a predetermined length on a side of the movable electrode base facing the fixed electrode finger group; The movable electrode fingers are arranged to be inserted with a space between the fixed electrode fingers, and suction generated between the fixed electrode fingers and the movable electrode fingers by applying an electric field or a magnetic field between the fixed electrode fingers. Movable electrodes made movable by force,
A suspension supporting member for supporting the movable electrode rotatably,
Wherein the one the stationary electrode fingers of the one of the fixed electrode fingers and thereto is disposed between the other fixed electrode finger adjacent the fixed electrode fingers the movable electrode finger group of the fixed electrode finger group A pair of movable electrode fingers having different heights in the direction of rotation, and a wide gap region by making the widths of the gap between the one fixed electrode finger and the gap between the other adjacent fixed electrode fingers different from each other means for forming a biasing electrode finger arrangement sets forming the narrow gap region, arranging a plurality of the biasing electrode finger arrangement sets over the axis interposed therebetween predetermined to opposite sides facing the length of the suspension supporting member,
A biased electrode finger array set on one side of the opposite side has a height of the movable electrode finger lower than a height of the fixed electrode finger, and a biased electrode finger array set on the other side of the opposite side has a height of the movable electrode finger. Means for lowering the height of the fixed electrode fingers than the height, and the comb is characterized in that the whole attractive force is balanced over the predetermined length by the biased electrode finger array set. It is in a tooth type actuator.

  Furthermore, the positions of the wide gap region and the narrow gap region of the plurality of biased electrode finger arrays arranged along the predetermined length may be symmetrically arranged with respect to the line symmetry center line of the movable electrode. it can.

  Furthermore, the movable electrode finger group may be separately disposed on both sides of the line symmetry center line of the movable electrode.

  In addition, the ratio of the gap width between the narrow gap region and the wide gap region may be 1: 1.2 to 1: 2.5.

  Further, the fixed electrode finger group and the movable electrode finger group may substantially comprise a biased electrode finger array set.

  Furthermore, the fixed electrode and the movable electrode may be disposed flush with each other.

  Furthermore, the gap between the fixed electrode finger and the movable electrode finger can be substantially parallel along the length of these electrode fingers.

  Furthermore, the gap between the fixed electrode finger and the movable electrode finger may be such that at least one of the wide gap region and the narrow gap region is non-parallel along the length of the electrode finger.

  Further, the fixed electrode finger and the movable electrode finger may have different heights.

  Further, the suspension support can form an axis around which the movable electrode rotates.

  Further, the movable electrode finger may have a substantially triangular or trapezoidal cross section, and the fixed electrode finger may have a substantially inverted triangular or inverted trapezoidal cross section.

  Furthermore, a mirror can be provided on one surface of the movable electrode.

  Further, the movable electrode can form a reflection or transmission type optical filter.

  Furthermore, it is preferable to apply a voltage between the fixed electrode and the movable electrode and to attract with an electrostatic force.

In another aspect of the present invention, a substrate in which an opening is formed,
A fixed electrode base comprising a plurality of fixed electrode fingers provided on the substrate along the opening and arranged in a comb-like shape over a predetermined length on a side of the fixed electrode base; A fixed electrode;
The movable electrode finger group includes a movable electrode base and a movable electrode finger group including a plurality of movable electrode fingers arranged in a comb-like shape over a predetermined length on a side of the movable electrode base. Movable electrode fingers are interleaved and arranged with a space between the fixed electrode fingers, and can be moved by electrostatic force generated between the fixed electrode fingers and the movable electrode fingers by applying a voltage between the fixed electrode fingers. Movable electrodes,
Fixed portions provided on both sides of the movable electrode and supporting the movable electrode;
A suspension supporting member which rotatably hanger pivotally supports the movable electrode integrally connected to said fixed portion and said movable electrode,
One fixed electrode finger in the fixed electrode finger group, another fixed electrode finger adjacent to the fixed electrode finger group, and one of the movable electrode finger groups arranged between these electrode fingers, A pair of movable electrode fingers having different heights in the rotating direction, and a gap formed between the movable electrode finger and the one fixed electrode finger, and the other fixed electrode adjacent to the movable electrode finger A biased electrode finger array set in which a wide gap region and a narrow gap region are formed by making the width of a gap formed between the fingers different from each other, and a plurality of the electrodes are opposed to opposite sides across the axis of the suspension support. Means for positioning over a predetermined length ;
A biased electrode finger array set on one side of the opposite side has a height of the movable electrode finger lower than a height of the fixed electrode finger, and a biased electrode finger array set on the other side of the opposite side has a height of the movable electrode finger. and provided with a <br/> means to reduce the height of the stationary electrode fingers than the height, characterized in that so as to balance the overall electrostatic power over the predetermined length by the electrode finger arrangement sets It is in the comb-tooth actuator.

  Further, the movable electrode is formed in a substantially quadrilateral shape, has movable electrode finger groups on two opposite sides, the suspension support is connected to the other two sides, and a pair of the fixed electrodes are formed on the two sides. The movable electrode finger group may be disposed on the substrate.

  In addition, a voltage may be applied to the movable electrode via the suspension support.

  According to the present invention, a comb-shaped actuator that prevents contact between a movable electrode and a fixed electrode is obtained. Further, the present invention provides a comb-shaped actuator that eliminates the instability of electrostatic force due to the dimensional shape error of the electrode finger due to manufacturing.

  Embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
In the present embodiment, the present invention is applied to an optical variable attenuator 10 as shown in FIG. 1, and in the figure, two light beams from the other end face of a cylindrical container 14 having electrode lead terminals 12 and 13 on a stem 11 are shown. Fibers 15 and 16 are introduced. The container 14 includes a two-core fiber collimator 17, a lens 18, and a mirror 19 that can adjust the reflection angle, and further includes a comb-shaped actuator 20 that controls the mirror 19 on the stem surface.

  In the operation of the optical variable attenuator 10, the light incident from the light incident side fiber 15 shown in FIG. 1 passes through the two-core fiber collimator 17 and the lens 18 and is reflected by the mirror 19. The reflected light passes through the lens 18 again and is coupled to the output side optical fiber 16. When the angle of the reflected light is adjusted by tilting the mirror 19, the amount of light incident on the light output side fiber 16 changes. That is, a coupling loss corresponding to the angle is generated, and the attenuation of light can be varied. The comb-shaped actuator 20 operates to tilt the mirror 19. The comb-shaped actuator 20 is fixed to the stem 11 of the container and is electrically connected to the electrode lead terminals 12 and 13, and a mirror is formed on one surface of the movable electrode. The required voltage is supplied from the power source 10a to the electrode lead terminal.

  As shown in FIG. 2 and FIG. 3, the comb-shaped actuator 20 is a conductive material formed of a Si layer on a frame-like Si substrate 21 on which an oxide insulating film 61 having an opening 22 formed at the center is formed. A fixed electrode 30 and a movable electrode 40 are disposed. Fixed electrodes 30a and 30b are arranged on opposite sides of the substrate 21, for example, upper and lower sides 23a and 23b, and the pair of electrodes are electrically connected by connection layers 31a and 31b along outer edges of the other opposite sides 23c and 23d of the substrate. . As shown in FIGS. 2 and 4, a plurality of comb-shaped fixed electrode fingers 32 protrude perpendicularly from the fixed electrode base 35 at equal intervals on the side of the opening 22 of both the fixed electrodes 30a and 30b and are arranged in parallel along the electrode base edge. The fixed electrode finger group 33 is formed.

  Projecting portions 24a and 24b project from the substrate on the inner edges of the left and right opposite sides 23c and 23d of the substrate 21 on the opening 22 side, and fixed portions 41a and 41b that also serve as an electrical connection of the movable electrode are disposed on the upper surface. . Due to the formation of the protruding portion, the opening 22 has an H shape, and the movable electrode 40 having an H pattern substantially the same shape as this shape is installed on the opening 22. Recess cuts 26a and 26b are provided at the center of the tip ends 25a and 25b of the protrusions 24a and 24b, and two slits are cut in the fixing portions 41a and 41b corresponding to the cuts of the recesses and formed between the slits. Suspension support bodies 42a and 42b for the movable electrode 40 that are elongated and have a small cross section are formed. The movable electrode 40 is mechanically and electrically connected to the fixed portions 41 a and 41 b by the pair of suspension supports 42 a and 42 b and is suspended from the opening 22.

  Comb-like electrode fingers 44 are arranged in parallel with long and opposite long sides 40a and 40b on the upper and lower sides of the movable electrode base 46 of the movable electrode 40 along the sides to provide a movable electrode finger group 45. As shown in FIG. 5, the height h2 of the movable electrode finger 44 is lower than the height h1 of the fixed electrode finger 32. In FIG. 2, the movable electrode group on the upper side and the movable electrode finger group on the lower side in FIG. Then, the arrangement relationship in the height direction of the electrode fingers is reversed as shown in FIG. 5A on the upper side and FIG. 5B on the lower side. Therefore, when a potential difference is generated between the electrodes, it is driven as indicated by an arrow.

  When both sides have the same positional relationship in the height direction, a voltage is applied to the fixed electrode on one side with the pair of fixed electrodes 30a and 30b in FIG.

  The fixed electrode finger group 33 of the fixed electrode and the movable electrode finger group 45 of the movable electrode are opposed to each other, and the electrode fingers 32 and 44 of both electrodes are in non-contact with each other to form an interdigital electrode arrangement.

  The pattern of the movable electrode 40 is axisymmetric with respect to the electrode center line C crossing both electrode finger groups at the center, and the electrode fingers are formed symmetrically with respect to the center line C.

The m-th movable electrode finger 44 _m is positioned between the m-th fixed electrode finger 32 _m and the (m + 1) -th fixed electrode finger 32 _{(m + 1)} adjacent to the m-th fixed electrode finger 32 _m from the center line C in FIG. when placed convoluted, distance g1 of the m-th fixed electrode finger 32 _m and m-th movable electrode fingers 44 gap between the _m or center line C side of the gap 51, (m + 1) th fixed electrode finger _{32 (m + 1)} widely than the gap g2 of the gap or the outer gap 52 between the m-th movable electrode finger 44 _m and.

  In this embodiment, when the arrangement of electrode fingers having such an arrangement, that is, an arrangement in which the insertion position of one movable electrode finger is shifted by a gap between two fixed electrode fingers is referred to as a biased electrode finger arrangement set in the present embodiment, Then, a biased electrode finger array set 50 having a wide center side gap g1 with respect to the center line C is disposed over the entire length of the electrode finger groups 33 and 45.

  Due to the symmetrical arrangement with respect to the center line of the bias electrode finger array set, as shown in FIG. 6 (A), the attractive force component of the electrostatic force outside the movable electrode with reference to the center line C by applying voltage to each bias electrode finger array set. Is generated, the suction force F is increased, and the center line C is balanced. The larger the suction force component as the action and reaction is, the easier it is to control and balance. Therefore, it becomes easy to correct the variation in the attractive force caused by the dimensional error of the electrode shape when manufacturing the electrode. In the case of a micro structure in which the dimension of the electrode finger of FIG. 14 is, for example, a length l of 100 μm, a height h of 50 μm, and a width w of about 15 μm or less, the ratio of the wide gap region spacing g1 to the narrow gap region spacing g2 Is preferably 1: 1.2 to 1: 2.5. If it is less than 1: 1.2, the electrostatic force of the biased electrode finger set tends to vary due to the manufacturing error of the dimensions, and if it exceeds 1: 2.5, the fixed electrode finger and the movable electrode finger are likely to come into contact with each other on the narrow gap side. Become. In this embodiment, it is 1: 1.5.

  On one surface of the movable electrode 40, a mirror 19 formed of a deposition layer of Ag or Al in addition to Au or a reflection layer of a multilayer interference film is disposed. The movable electrode 40 is pivotally supported by the suspension supports 42a and 42b. When a voltage is applied between the movable electrode 40 and the fixed electrode 30, the movable electrode 40 is electrostatically driven by the electrode finger group and rotates. Accordingly, the angle of the mirror with respect to the optical axis of the light from the fiber 15 shown in FIG. 1 is adjusted.

  In the above embodiment, the biased electrode finger array set is applied over the entire length of the electrode finger group, but may be applied to a part. For example, it may be arranged every other one, and can be formed in the vicinity of the ends of the electrode finger group. Alternatively, an electrode finger group in which the gap interval is not the same dimension may be used. In either case, the electrostatic force of the electrode finger gap of the biased electrode finger set is symmetrically increased so as to exceed the undesired rotational electrostatic force in the movable electrode surface direction caused by the manufacturing error of the electrode finger when it is not biased. Electricity can be used.

  Further, in the above embodiment, as shown in FIG. 6A, the center side gap interval of the biased electrode finger array set is made wider than the outer gap interval, and the suction force to the outside is increased. The distance between the side gaps can be made narrower than the distance between the outer gaps, and the center line C can be balanced with reference to the center line C so as to increase the suction force F toward the center as shown in FIG. Further, it is also possible to arrange the bias electrode finger arrangement groups having the gaps opposite to each other so as to interweave to the left and right of the center line C. By positively forming the bias electrode pairs, it is possible to eliminate an undesired bias of electrostatic force due to manufacturing errors.

  Hereinafter, the manufacturing method of this embodiment will be described with reference to FIG. For ease of understanding, the figure schematically shows the movable electrode 40 having electrode fingers that are lower in height than the fixed electrode, and the fixed electrode 30 having the fixed electrode fingers is also formed at the same time. It is shown.

(Process A)
An SOI substrate in which a single crystal Si electrode layer 62 having a thickness of 50 μm is stacked on a single crystal Si substrate 21 having a thickness of 500 μm via a Si oxide film 61 is prepared, and used as a mask on the electrode layer 62 in a later step. An Al layer 63 to be deposited is deposited by sputtering. A part of the Al layer 63 on the region 44a to be the movable electrode finger 44 (FIG. 4) of the Si electrode layer 62 is removed by etching to form an opening 63a.

(Process B)
The upper surface of the substrate including the Al layer is covered with a photoresist layer 64, and the photoresist layer 64 is exposed to light using a mask which mainly forms a movable electrode pattern of the actuator to remove a part of the mask holes 64a, 64b, 64c is formed. The Si electrode layer under the mask holes 64a and 64c is a region to be removed as a gap between the movable electrode 40, the fixed electrode 30 and the protrusions 24a and 24b that fix the movable electrode shown in FIG. 1, and the mask hole 64b is a protrusion. Mask holes for forming recess cuts 26a and 26b in the sharpened heads 25a and 25b of 24a and 24b are regions where the cuts are formed as suspension support bodies 42a and 42b (FIG. 2).

  In the regions under the mask holes 64a, 64b and 64c, the Si electrode layer 62 is etched by anisotropic etching with ions, and the Si electrode layer 62 is etched to a depth of 30 μm.

(Process C)
Using the exposed Al layer 63 as a mask, the Si electrode layer 62 is anisotropically etched with ions, and the region 62a that has already been etched to a depth of 30 μm and remains about 20 μm thick is removed. Etching is performed until the Si oxide layer 61 is exposed. As a result, like the region 44a of the Al layer opening 63a, the movable electrode finger 44 is cut by 20 μm and becomes 30 μm high (in the thickness direction of the Si electrode layer).

(Process D)
The Al layer 63 is removed, and photoresist films 65 and 66 are applied to both sides of the substrate. The resist film 66 for forming the opening 22 on the back surface of the substrate is irradiated with light and developed to form a mask hole, and anisotropic etching is performed to remove the Si region 21 and the Si oxide film 61 under the mask hole to open the opening. Part 22 is assumed.

  The obtained movable electrode finger 44 has a width w of 15 microns and a length l of 100 μm. The electrode fingers are arranged in parallel along the edge of the movable electrode base 46 on each side of the center line C (FIG. 1). At the same time, the suspension support 42 is formed to have a width of 5 μm and a height of 50 μm.

(Process E)
The photoresist films 65 and 66 are removed, and an Au layer 67 is deposited on the upper surface of the Si electrode layer 62 by sputtering. This Au layer functions as the mirror 19 on the movable electrode, and also serves as a bonding pad for supplying a voltage to the fixed electrode 30 and the movable electrode fixing portions 41a and 41b. In the figure, a broken line portion 32 indicates a fixed electrode finger.

  In this manner, a 2 mm × 3 mm square comb-shaped actuator in which the fixed electrode and the movable electrode are formed on the same surface is manufactured. This is mounted on the stem 11 of the container shown in FIG. 1, and the electrode lead terminals 12 and 13 are connected to the fixed electrode and the movable electrode by bonding wires. The optical fibers 15 and 16, the two-core fiber collimator 17, and the lens 18 are attached, and the optical variable attenuator 10 is manufactured by covering with a cap that becomes the cylindrical container 14 and sealing.

( Reference example )
This reference example shows an actuator in which the position of the suspension support of the movable electrode is a cantilever structure, and has the same configuration as the upper half of the first embodiment.

As shown in FIGS. 8A and 8B, the comb-shaped actuator 70 includes a movable electrode body 72 having a line-symmetric T-shaped pattern centered on the line-symmetrical center line C, and an electrode base portion symmetrically from the body. The left and right arm portions 73 and 74 are extended, and a pair of fixed electrodes 71a and 71b are disposed on the upper edge portions thereof. Fixing portions 75a and 75b for fixing the movable electrode and also serving as electrode pads of the movable electrode are arranged at the front end sides of the left and right arm portions 73 and 74 with a space therebetween. The upper extension 76a of the movable electrode forms the main body of the movable electrode, and the mirror 19 is formed on one surface. The lower extension portion 76b of the movable electrode is formed so as to slightly protrude from the lower edges of the left and right arm portions 73 and 74. Suspension support members 77a and 77b are provided from the side edges to the fixed portions 75a and 75b. It is suspended from the fixing portions 75a and 75b.

  A movable electrode finger group 78 made up of a plurality of movable electrode fingers 73a is formed above the left and right arm portions 73, 74 of the movable electrode, and a fixed electrode finger group made up of a plurality of fixed electrode fingers 71c on the sides of the fixed electrodes 71a, 71b facing each other. 79 is formed, and the movable electrode finger group 78 and the fixed electrode finger group 79 are arranged so as to interlace each other. As shown in FIG. 8B, the structural arrangement of the movable electrode fingers 73a and the fixed electrode fingers 71c is the same as that of the first embodiment, and the biased electrode finger array set 80 is arranged over the entire length of the electrode finger group. That is, the biased electrode finger array set 80 is composed of one movable electrode finger 73a and a pair of fixed electrode fingers 71c sandwiching the movable electrode finger 73a, and this array set has a wide gap g1 between the movable electrode and the pair of fixed electrodes. A narrow gap g2 is formed.

This reference example as the midpoint of the line symmetry center line C, the left biasing electrode finger pairs of the wide gap g1 of the electrode finger to the center line C side, similarly biased on the right side of the electrode finger groups the electrode finger pairs of the wide gap g1 Are arranged on the center line C side so that the electrostatic force generated in the entire electrode is balanced. When a voltage is applied between the fixed electrode and the movable electrode, an electrostatic force is generated between the electrode fingers, and the movable electrode 72 rotates about the suspension supports 77a and 77b to adjust the angle of the mirror 19. By maintaining a constant voltage, the movable electrode is stopped and the desired mirror angle is fixed.

( Second Embodiment )
As shown in FIG. 9, the present embodiment has a structure in which a transmissive interference filter 85 is disposed on the movable electrode 40. In addition, the part of the same code | symbol as 1st Embodiment shows a similar part. An interference filter 85 is formed by depositing a multilayer interference film on the Si movable electrode base 46. Since the Si substrate is transparent in the infrared region of the used light, the multilayer interference film functions as a filter. The electrode finger groups 33 and 45 are configured by arranging a biased electrode finger array set symmetrically with respect to the center line C, thereby ensuring ease of manufacture and control. It is also possible to configure a reflection type with an interference filter.

( Third embodiment )
In the present embodiment, unlike the single suspension support of the first embodiment, the suspension support 90 between the movable electrode 40 and the fixed portion 41 is composed of two thin wires 91a and 91b as shown in FIG. In addition, the part of the same code | symbol as 1st Embodiment shows a similar part. Since the support body is formed by two adjacent thin wires, the movable electrode 40 can be firmly held by the support body having a relatively small cross section. In addition, the part of the same code | symbol as 1st Embodiment shows a similar part.

  The suspension support 90 has a micro structure with a cross section of 5 μm × 50 μm or less, and is made of a single crystal Si or the like. Therefore, the suspension support 90 is extremely fragile and ensures mechanical strength as a suspension of the movable electrode. The dimensions must be increased. However, if the size is increased, there is a limit to the torsion control of the suspension support for rotating the movable electrode, so that the movable electrode is axially supported (axis line a) by two adjacent supports as in this embodiment. Thus, such inconvenience can be prevented.

  As mentioned above, although this invention was demonstrated by embodiment, the scope of the present invention is not limited to embodiment. For example, the wide gap and narrow gap of the biased electrode finger array set can be formed with the same distance in the width direction between the fixed electrode finger and the movable electrode finger over the length of the electrode finger but not with the same size. . For example, the movable electrode finger can be tapered so that the electrostatic force component applied to the entire electrode finger is biased in a desired direction. The tip of the electrode finger can be round, chamfered, sharp, concave, or curved to generate a biased electrostatic force. Moreover, the shape where the side edge of an electrode finger curves with respect to the side edge of the electrode finger which opposes may be sufficient. If necessary, the effect of the present invention can be obtained by setting the wide gap and the narrow gap as a whole even if they are not parallel.

  In addition, as a modification of the electrode finger, the cross-section of the electrode finger can be a quadrilateral such as a trapezoid or a rhombus other than a rectangle, a triangle or another polygon. When the movable electrode fingers are trapezoidal or triangular, the moving range of the movable electrodes in the gap direction can be widened by combining the fixed electrode fingers in an inverted trapezoidal shape or an inverted triangular shape in an inverted shape.

  Furthermore, in the above embodiment, the set of biased electrode finger arrangements is composed of a pair of fixed electrode fingers and one movable electrode finger, but may be composed of a pair of movable electrode fingers and one fixed electrode finger. Further, a set of biased electrode finger arrangements can be configured by forming a wide gap and a narrow gap between fixed electrode fingers sandwiching each pair of two movable electrode fingers.

  Furthermore, although the said embodiment is a structure which applies a common voltage to a pair of fixed electrode, you may make it isolate | separate and apply an independent voltage.

  The above embodiment has a structure in which the electrode is made of Si and the Au layer is deposited on the upper surface thereof. However, a conductive electrode can be made of only a semiconductor such as Si, and the upper surface of the electrode base is made of an insulator. A conductive layer can be formed by providing a metal layer of Au or the like. Moreover, you may form an electrode with metal layer itself.

  The movable electrode and the fixed electrode can be made of a magnetic material, and a magnetic field can be applied between them to generate an attractive force.

  Although the above embodiment has been described with the comb-type actuator of the optical variable attenuator, it is needless to say that it can be applied to, for example, an optical switch of an optical communication system, a wavelength tunable device of a laser resonator, a wavelength filter, or the like. .

1 is a schematic sectional view of an optical variable attenuator according to an embodiment of the present invention. FIG. 2 is a schematic plan view of the comb-shaped actuator of the embodiment of FIG. 1. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. The enlarged plan view explaining the electrode finger of one embodiment of the present invention. (A) (B) is a side view explaining the shape and operation | movement of a movable electrode finger. The schematic diagram explaining operation | movement of the one real form of this invention. (A) thru | or (E) are the cross-sectional schematic diagrams explaining the manufacturing method of one Embodiment of this invention. The schematic plan view explaining the reference example of this invention. The schematic plan view explaining other embodiment of this invention. The schematic plan view explaining other embodiment of this invention. The schematic plan view of the conventional comb-tooth type actuator. The schematic diagram explaining the electrode finger of the conventional comb-shaped actuator. (A) and (B) are schematic diagrams for explaining operations of a fixed electrode finger and a movable electrode finger. The schematic perspective view explaining the dimension of an electrode finger.

Explanation of symbols

10: variable optical attenuator 19: mirror 20: comb-shaped actuator 30: fixed electrode 32: fixed electrode finger 33: fixed electrode finger group 35: fixed electrode base 40: movable electrodes 41a, 41b: fixed portions 42a, 42b: suspension Support 44: Movable electrode finger 45: Movable electrode finger group 46: Movable electrode base 50: Biased electrode finger array set 51, 52: Gap g1, g2: Gap interval

Claims (14)

A fixed electrode having a conductive fixed electrode base and a fixed electrode finger group composed of a plurality of fixed electrode fingers arranged in a comb-like shape over a predetermined length on at least one side of the fixed electrode base;
A conductive movable electrode base, and a movable electrode finger group including a plurality of movable electrode fingers arranged in a comb-like shape over a predetermined length on a side of the movable electrode base facing the fixed electrode finger group; The movable electrode fingers are arranged to be inserted with a space between the fixed electrode fingers, and suction generated between the fixed electrode fingers and the movable electrode fingers by applying an electric field or a magnetic field between the fixed electrode fingers. Movable electrodes made movable by force,
A suspension supporting member for supporting the movable electrode rotatably,
One fixed electrode finger in the fixed electrode finger group, another fixed electrode finger adjacent to the fixed electrode finger, and one of the movable electrode fingers arranged between the fixed electrode fingers and the fixed electrode finger A pair of movable electrode fingers having different heights in the direction of rotation, and a wide gap region by making the widths of the gap between the one fixed electrode finger and the gap between the other adjacent fixed electrode fingers different from each other means for forming a biasing electrode finger arrangement sets forming the narrow gap region, arranging a plurality of the biasing electrode finger arrangement sets over the axis interposed therebetween predetermined to opposite sides facing the length of the suspension supporting member,
A biased electrode finger array set on one side of the opposite side has a height of the movable electrode finger lower than a height of the fixed electrode finger, and a biased electrode finger array set on the other side of the opposite side has a height of the movable electrode finger. Means for lowering the height of the fixed electrode fingers than the height, and the comb is characterized in that the whole attractive force is balanced over the predetermined length by the biased electrode finger array set. Tooth type actuator.   2. The positions of the wide gap region and the narrow gap region of the plurality of biased electrode finger arrays arranged along the predetermined length are symmetrically arranged with respect to a line symmetry center line of the movable electrode. Comb-shaped actuator.   The comb-shaped actuator according to claim 1, wherein the movable electrode finger group is separately arranged on both sides of a line symmetry center line of the movable electrode.   The comb-shaped actuator according to claim 1 or 2, wherein a ratio of a gap width between the narrow gap region and the wide gap region is 1: 1.2 to 1: 2.5. Comb type actuator according to claim 1 or 2, wherein the movable electrode finger group and the fixed electrode finger group is characterized in that it consists of the polarized倚electrode finger arrangement sets.   The comb-shaped actuator according to claim 1, wherein the fixed electrode and the movable electrode are arranged flush with each other.   The comb-shaped actuator according to claim 1 or 2, wherein a gap between the fixed electrode finger and the movable electrode finger is substantially parallel to a length of these electrode fingers. The comb-shaped actuator according to claim 1 or 2, wherein a mirror is provided on one surface of the movable electrode. The comb-shaped actuator according to claim 1, wherein the movable electrode forms a transmissive optical filter. The comb-shaped actuator according to any one of claims 1 to 9, wherein a voltage is applied between the fixed electrode and the movable electrode. A substrate having an opening formed thereon;
A fixed electrode base comprising a plurality of fixed electrode fingers provided on the substrate along the opening and arranged in a comb-like shape over a predetermined length on a side of the fixed electrode base; A fixed electrode;
The movable electrode finger group includes a movable electrode base and a movable electrode finger group including a plurality of movable electrode fingers arranged in a comb-like shape over a predetermined length on a side of the movable electrode base. Movable electrode fingers are interleaved and arranged with a space between the fixed electrode fingers, and can be moved by electrostatic force generated between the fixed electrode fingers and the movable electrode fingers by applying a voltage between the fixed electrode fingers. Movable electrodes,
Fixed portions provided on both sides of the movable electrode and supporting the movable electrode;
A suspension support body that is integrally connected to the movable electrode and the fixed portion and supports the movable electrode so that the movable electrode can rotate;
One fixed electrode finger in the fixed electrode finger group, another fixed electrode finger adjacent to the fixed electrode finger group, and one of the movable electrode finger groups arranged between these electrode fingers, A pair of movable electrode fingers having different heights in the rotating direction, and a gap formed between the movable electrode finger and the one fixed electrode finger, and the other fixed electrode adjacent to the movable electrode finger A biased electrode finger array set in which a wide gap region and a narrow gap region are formed by making the width of a gap formed between the fingers different from each other, and a plurality of the electrodes are opposed to opposite sides across the axis of the suspension support. Means for positioning over a predetermined length;
A biased electrode finger array set on one side of the opposite side has a height of the movable electrode finger lower than a height of the fixed electrode finger, and a biased electrode finger array set on the other side of the opposite side has a height of the movable electrode finger. Means for lowering the height of the fixed electrode finger than the height;
The comb-shaped actuator is characterized in that the electrostatic force is balanced over the predetermined length by the electrode finger array set. The movable electrode is formed in a substantially quadrilateral shape, has movable electrode finger groups on two opposite sides, the suspension support is connected to the other two sides, and a pair of the fixed electrodes are movable on the two sides. The comb-shaped actuator according to claim 11, wherein the comb-shaped actuator is arranged on the substrate corresponding to an electrode finger group. The comb-shaped actuator according to claim 1 or 11, wherein a voltage is applied to the movable electrode via the suspension support. A light control element using the comb-shaped actuator according to claim 1.

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