JP4329402B2 - Microactuator array, microactuator device, optical switch array and optical switch system using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microactuator array, a microactuator device using the same, an optical switch array, and an optical switch system. Such an optical switch array can be used for optical communication, for example.
[0002]
[Prior art]
With the progress of micromachining technology, the importance of actuators is increasing in various fields. As an example of a field in which microactuators are used, for example, an optical switch used for optical communication or the like to switch an optical path can be cited. As an example of such an optical switch, for example, an optical switch disclosed in Patent Document 1 below can be cited.
[0003]
The microactuator generally has a fixed portion and a movable portion that can be moved by a predetermined force, and is held at a predetermined position by the predetermined force. In the conventional microactuator, an electrostatic force is often used as the predetermined force. For example, in a microactuator that moves a micromirror used in the optical switch disclosed in Patent Document 1 below, the movable part is moved to an upper position (a position where the micromirror reflects incident light) and a lower position (a position where the micromirror reflects incident light) by electrostatic force. The micromirror is moved to a position where the incident light is allowed to pass through and is held at that position.
[0004]
In such a microactuator using electrostatic force, the first electrode part is arranged in the fixed part, the second electrode part is arranged in the movable part, and a voltage is applied between the first and second electrode parts. An electrostatic force is generated between the two.
[0005]
[Patent Document 1]
JP 2001-42233 A
[0006]
[Problems to be solved by the invention]
In the conventional microactuator using the electrostatic force as described above, the movable portion is moved by the electrostatic force and held at a predetermined position by the electrostatic force, so it is difficult to widen the movable range of the movable portion. .
[0007]
Electrostatic force F acting between parallel plate electrodes₁If the dielectric constant ε, the potential difference V, the inter-electrode distance d, and the electrode area S are used, the following equation 1 is obtained.
[0008]
[Expression 1]
F₁= Ε × V²× S / 2d²
[0009]
As can be seen from Equation 1, when the inter-electrode distance d increases, the electrostatic force F is inversely proportional to the square thereof.₁Decreases rapidly. Therefore, in the conventional microactuator, it is difficult to move the movable part when the inter-electrode distance d exceeds a certain distance, and it is difficult to widen the movable range of the movable part. Also, a sufficient electrostatic force F for a large interelectrode distance d₁If the potential difference (voltage between the electrodes) V is increased, a problem arises in terms of dielectric strength, or a high voltage generator is required. Also, a sufficient electrostatic force F for a large interelectrode distance d₁If the electrode area S is increased in order to obtain the above, the size increases, and the original purpose of the microactuator of downsizing is impaired.
[0010]
Thus, as a result of research, the present inventor has come up with the idea of using Lorentz force instead of electrostatic force in a microactuator.
[0011]
Lorentz force F₂It is known that (N) is as shown in the following formula 2, where B (T) is the magnetic flux density, L (m) is the length of the wire, and I (A) is the current.
[0012]
[Expression 2]
F₂= I × B × L
[0013]
Since there is no item that defines the position of the wire in Equation 2, the Lorentz force F generated even if the position of the wire changes within a certain magnetic flux density.₂Does not change.
[0014]
In the microactuator, if a current path corresponding to the electric wire is provided in the movable part, a magnetic field is applied to the current path, and a current flows through the current path, Lorentz force can be applied to the movable part. Even if the movable range of the movable portion is wider than the conventional one, it is easy to apply a substantially uniform magnetic field in that range, for example, by using a magnet. Therefore, even if the movable range of the movable part is wide, a constant force can be applied to the movable part regardless of the position of the movable part. In other words, in a microactuator, if Lorentz force is used instead of electrostatic force, a constant driving force can be obtained regardless of the position of the movable part, unlike the case of using electrostatic force that changes the driving force depending on the position of the movable part. But in principle.
[0015]
For example, if the electrode interval is 50 μm, the electrode shape is 50 μm square, the voltage is 5 V, and the dielectric constant is 1, the electrostatic force F of Equation 1 is used.₁Is 0.1 nN. On the other hand, if a current path having a length of 50 μm is created in a 50 μm square electrode and a magnetic field having a magnetic flux density of 0.1 T is applied, a 5 nN Lorentz force is generated when a current of 1 mA is applied. In order to obtain a force of 5 nN or more with an electrostatic force, the electrode interval must be 7 μm or less or the electrode shape must be 350 μm square or more, and the Lorentz force is more advantageous to obtain the same driving force. Recognize.
[0016]
For example, if a 20 mm square neodymium iron boron-based magnet is disposed at a position 2 mm away from the microactuator, a magnetic flux density of 0.1 T can be easily obtained.
[0017]
As described above, in the microactuator, when the Lorentz force is used instead of the electrostatic force, the movable range of the movable portion can be expanded without applying a high voltage or impairing downsizing.
[0018]
However, it has been found that when a Lorentz force is used instead of an electrostatic force in a microactuator, a new problem arises. That is, when Lorentz force is used instead of electrostatic force, the movable part is moved to a predetermined position by Lorentz force, and the movable part is continuously held at that position by Lorentz force. Therefore, since the current for generating the Lorentz force is always kept flowing, the power consumption is remarkably increased.
[0019]
In a microactuator array having a plurality of microactuators, it is preferable that the amount of flowing current is as small as possible because the current capacity is very limited from the viewpoint of miniaturization and the like.
[0020]
The present invention has been made in view of such circumstances, and can extend the movable range of the movable part and reduce power consumption without applying a high voltage or impairing downsizing. Another object of the present invention is to provide a microactuator array that can reduce the amount of flowing current, and a microactuator device, an optical switch array, and an optical switch system using the microactuator array.
[0021]
[Means for Solving the Problems]
As a result of further research, the present inventor has found that the above-described object can be achieved by configuring the microactuator so that the use of electrostatic force and the use of Lorentz force can be combined. That is, in a microactuator including a fixed portion and a movable portion provided so as to be movable with respect to the fixed portion, an electrode portion for allowing an electrostatic force to act on the movable portion is fixed and movable. It has been found that the above-described object can be achieved by providing each of the movable portions with a current path for applying a Lorentz force to the movable portion.
[0022]
By adopting this means, for example, when the distance between the electrode part of the movable part and the electrode part of the fixed part is large, the movable part is moved only by the Lorentz force, and the electrode part of the movable part and the electrode part of the fixed part are moved. When the distance between and becomes small, it becomes possible to hold the movable part only by the electrostatic force. As a result, the movable range of the movable portion can be expanded without applying a high voltage or impairing downsizing, and power consumption can be reduced.
[0023]
In electrostatic driving, since the capacitor is electrically charged and discharged, power consumption occurs only at the time of charging and discharging, that is, at the time of voltage change. Therefore, unlike a microactuator used in an optical switch or the like, the movable part does not move frequently and the movable part is held at a predetermined position (position where the distance between the electrode part of the fixed part and the electrode part of the movable part is small). In the case where the period of time is relatively long, the power consumption can be greatly reduced if the force for holding the movable portion in a predetermined position is generated only by the electrostatic force. In addition, at a position where the distance between the electrode part of the fixed part and the electrode of the movable part is small, a sufficiently large electrostatic force can be obtained even if the voltage between them is relatively low and the electrode area is relatively small. It is done.
[0024]
In Lorentz force driving, a constant driving force can be obtained regardless of the position of the movable part. Therefore, if the movable part is moved by the Lorentz force, the movable range can be expanded. Although the Lorentz force power consumption is relatively large, if the Lorentz force is used only to move the movable part and the Lorentz drive is not performed when the movable part is held at a predetermined position by the electrostatic force, the aforementioned constant Lorentz force drive is used. Compared to the power consumption in the case of, it is greatly reduced.
[0025]
In this way, by mounting both the mechanism for generating electrostatic force and the mechanism for generating Lorentz force in the microactuator, for example, the force for holding the movable part at a predetermined position is generated by the electrostatic force. While reducing the power consumption, the actuator can be driven by Lorentz force when the distance between the movable electrode and the fixed electrode is wide, and the movable range can be expanded while suppressing the application of high voltage and the expansion of the electrode area. It becomes.
[0026]
Further, when configuring a microactuator array including a plurality of such microactuators, even if the current paths for Lorentz force of two or more of these microactuators are electrically connected in series, It was found that the microactuator can be operated properly. When the current paths for the Lorentz force of two or more microactuators are electrically connected in series, each of the microactuators can be used when a current is simultaneously passed through the current paths for the Lorentz force of the two or more microactuators. The amount of flowing current is reduced as compared with the case where the current paths for Lorentz force are electrically independent, and the case where the current paths for Lorentz force of the two or more microactuators are electrically connected in parallel.
[0027]
The present invention has been made on the basis of new knowledge based on the above-described research results of the present inventors.
[0028]
That is, in order to solve the above-described problem, the microactuator array according to the first aspect of the present invention is a microactuator array including a plurality of microactuators, and each of the microactuators can move with respect to a fixed portion. Between the first electrode part by a voltage between the movable part provided in the above-described manner, the first electrode part provided in the fixed part, and the first electrode part provided in the movable part. Two or more of the plurality of microactuators having a second electrode portion capable of generating an electrostatic force and a current path disposed in the magnetic field and generating a Lorentz force by energization. The current paths of the microactuators are electrically connected in series so as to generate Lorentz forces in the same direction when energized. The movable part is made of a thin film, for example.
[0029]
The microactuator array according to a second aspect of the present invention is the microactuator array according to the first aspect, wherein the plurality of microactuators are arranged in a two-dimensional matrix, and each column or each column has a microactuator array in the column or row. The current paths are electrically connected in series so as to generate Lorentz forces in the same direction when energized.
[0030]
In the microactuator array according to the third aspect of the present invention, in the first or second aspect, for each row, one of the first and second electrode portions of the microactuator in the row is electrically common. For each column, the other of the first and second electrode portions of the microactuator in the column is electrically connected in common.
[0031]
The microactuator array according to a fourth aspect of the present invention is the microactuator array according to any one of the first to third aspects. And a second position where the electrostatic force decreases or disappears, and a return force for returning to the second position is generated, and (b) for each microactuator The current path has a Lorentz force in a first direction or a second direction opposite thereto that moves the movable part from the second position to the first position according to the direction of energization. It is provided to occur.
[0032]
A microactuator device according to a fifth aspect of the present invention includes a microactuator array according to the fourth aspect, a magnetic field generator that generates the magnetic field, and potentials of the first and second electrode portions of the microactuators. And a control unit that performs control to switch the position of the movable part of each microactuator by controlling the current flowing through the current path.
[0033]
The microactuator device according to a sixth aspect of the present invention is the microactuator device according to the fifth aspect, wherein the control unit relates to at least one microactuator of the plurality of microactuators, and is at the first position of the movable part. When the movable part is switched from the second position to the first position, the potential of the first and second electrode parts is controlled so that the electrostatic force is held by the electrostatic force. A current having a direction corresponding to the first direction of the Lorentz force is passed, and the current is interrupted after the movable part is held at the first position by the electrostatic force.
[0034]
The microactuator device according to a seventh aspect of the present invention is the microactuator device according to the fifth or seventh aspect, wherein the control unit relates to at least one microactuator of the plurality of microactuators. When the movable part is switched from the first position to the second position, the potential of the first and second electrode parts is controlled so that the holding at the position is performed by the electrostatic force. A current is passed through the current path in a direction corresponding to the second direction of the Lorentz force.
[0035]
A microactuator device according to an eighth aspect of the present invention is the microactuator device according to any one of the fifth to seventh aspects, wherein the control unit relates to at least one microactuator of the plurality of microactuators. When the potential of the first and second electrode portions is controlled so that the holding at the first position is performed by the electrostatic force, and the movable portion is switched from the first position to the second position. In addition, the potentials of the first and second electrode portions are controlled so that the electrostatic force is reduced or the electrostatic force is lost as compared with the case where the movable portion is held at the first position. To do.
[0036]
The microactuator device according to a ninth aspect of the present invention is the microactuator device according to any of the fifth to eighth aspects, wherein the control unit relates to at least one microactuator of the plurality of microactuators, and In synchronization with a command signal indicating a command to switch from the first position to the second position, the voltage change between the first and second electrode portions and the second direction of the Lorentz force The energization of the current to the current path in the corresponding direction is started almost simultaneously.
[0037]
In the microactuator device according to a tenth aspect of the present invention, in any one of the fifth to ninth aspects, the control unit may apply an AC voltage between the first and second electrode portions. The potential of the first and second electrode portions is controlled. The AC voltage may be a pulse AC voltage or a sinusoidal AC voltage.
[0038]
An optical switch array according to an eleventh aspect of the present invention includes the microactuator array according to any one of the first to fourth aspects, and a mirror provided on each of the movable portions of the plurality of microactuators. Is.
[0039]
An optical switch system according to a twelfth aspect of the present invention includes the microactuator device according to any one of the fifth to eleventh aspects, and a mirror provided in each of the movable parts of the plurality of microactuators. Is.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a microactuator array according to the present invention, a microactuator device using the same, an optical switch array, and an optical switch system will be described with reference to the drawings.
[0041]
[First Embodiment]
[0042]
FIG. 1 is a schematic configuration diagram illustrating an example of an optical switch system including an optical switch array 1 according to a first embodiment of the present invention. For convenience of explanation, as shown in FIG. 1, an X axis, a Y axis, and a Z axis that are orthogonal to each other are defined (the same applies to the drawings described later). The surface of the substrate 121 of the optical switch array 1 is parallel to the XY plane. The direction of the arrow in the Z-axis direction is called the + Z direction or + Z side, and the opposite direction is called the -Z direction or -Z side, and the same applies to the X-axis direction and the Y-axis direction. The + side in the Z-axis direction may be referred to as the upper side, and the − side in the Z-axis direction may be referred to as the lower side.
[0043]
As shown in FIG. 1, the optical switch system according to the present embodiment includes an optical switch array 1, m optical input optical fibers 2, m optical output optical fibers 3, and n optical outputs. In response to the optical path switching state command signal, the optical path switching indicated by the optical path switching state command signal in response to the optical fiber 4 for use, the magnet 5 as a magnetic field generating unit that generates a magnetic field as will be described later with respect to the optical switch array 1 And an external control circuit 6 as a control unit that supplies a control signal for realizing the state to the optical switch array 1. In the example shown in FIG. 1, m = 3 and n = 3, but m and n may each be an arbitrary number.
[0044]
In the present embodiment, as shown in FIG. 1, the magnet 5 is a plate-like permanent magnet that is magnetized with an N-pole on the X-axis direction and an S-pole on the + side in the X-axis direction, and the lower side of the optical switch array 1. The magnetic field indicated by the magnetic force lines 5a is generated with respect to the optical switch array 1. That is, the magnet 5 generates a substantially uniform magnetic field toward the + side along the X-axis direction with respect to the optical switch array 1. However, instead of the magnet 5, for example, a permanent magnet having another shape, an electromagnet, or the like may be used as the magnetic field generation unit.
[0045]
As shown in FIG. 1, the optical switch array 1 includes a substrate 121 and m × n mirrors 12 arranged on the substrate 121. The m light input optical fibers 2 are arranged in a plane parallel to the XY plane so as to guide incident light from one side in the Y axis direction to the substrate 121 in the Y axis direction. The m optical output optical fibers 3 are arranged on the other side of the substrate 121 so as to face the m optical input optical fibers 2 and are not reflected by any mirror 12 of the optical switch array 1. Are arranged in a plane parallel to the XY plane so that light traveling in the Y-axis direction is incident on the XY plane. The n light output optical fibers 4 are arranged in a plane parallel to the XY plane so that light reflected by any mirror 12 of the optical switch array 1 and traveling in the X-axis direction is incident. . The m × n mirrors 12 can be advanced and retracted by a microactuator 111 (to be described later) with respect to the intersection of the outgoing optical path of the m optical input optical fibers 2 and the incident optical path of the optical output optical fiber 4. Are arranged on the substrate 121 in a two-dimensional matrix so as to be movable in the Z-axis direction. In this example, the orientation of the mirror 12 is set so that the normal line forms 45 ° with the X axis in a plane parallel to the XY plane. Of course, the angle can be changed as appropriate. When the angle of the mirror 12 is changed, the direction of the optical fiber 4 for light output may be set in accordance with the angle. FIG. 1 shows an apparatus for switching light beams in a space, and a lens may be inserted at the fiber end to improve the coupling with the light beam.
[0046]
The optical path switching principle itself of this optical switch system is the same as the optical path switching principle of the conventional two-dimensional optical switch.
[0047]
Next, the structure of one optical switch as a unit element of the optical switch array 1 in FIG. 1 will be described with reference to FIGS. FIG. 2 shows one optical switch (that is, one microactuator 111 and driven by this) as a unit element constituting the optical switch array used in the optical switch system according to the first embodiment of the present invention. 1 is a schematic plan view schematically showing one mirror 12). In FIG. 2, the SiN film 144 as a protective film formed over the entire surface of the movable part and the leg part is omitted, and the lines of the ridges 149 and 150 that should be originally written by solid lines are indicated by broken lines, The Al films 142 and 143 are hatched differently. FIG. 3 is a schematic cross-sectional view taken along line X11-X12 in FIG. Although not shown in the drawing, the schematic cross-sectional view along the line X19-X20 in FIG. 2 is the same as FIG. 4 is a schematic cross-sectional view taken along line X13-X14 in FIG. Although not shown in the drawing, the schematic cross-sectional view along the line X17-X18 in FIG. 2 is the same as FIG. FIG. 5 is a schematic sectional view taken along line X15-X16 in FIG. 6 is a schematic cross-sectional view taken along line Y11-Y12 in FIG. FIG. 7 is a schematic sectional view taken along line Y13-Y14 in FIG. FIG. 8 is a schematic sectional view taken along line Y15-Y16 in FIG. FIG. 9 is a schematic sectional view taken along line Y17-Y18 in FIG. 3 to 9 show that the beam components 132 and 134 are not curved in the Z-axis direction, the beam components 132 and 134 are actually received by the movable portion. In the absence, the beam constituting portions 132 and 134 are bent in the + Z direction by the stress of the film constituting the beam constituting portions 132 and 134.
[0048]
In the present embodiment, the microactuator 111 has a cantilever structure. However, in the present invention, the microactuator may have a both-end supported structure by a flexure portion, for example, as in the above-mentioned Patent Document 1.
[0049]
The microactuator 111 used in the present embodiment extends in parallel with the substrate 121 such as a silicon substrate or a glass substrate, the leg portions 122 and 123, and mainly in the X-axis direction in a plan view as viewed from the Z-axis direction. Two strip-shaped beam portions 124 and 125, and the ends of the beam portions 124 and 125 (free ends, + X-direction end portions) that are rectangular in a plan view that mechanically connects between them. The connecting portion 126, the connecting portion 127 that mechanically connects the fixed end sides of the beam constituting portion 133 constituting the beam portion 124 and the beam constituting portion 135 constituting the beam portion 125 for reinforcement, and a fixed electrode (first electrode) 1 electrode portion) 128.
[0050]
The fixed ends (ends in the −X direction) of the beam portion 124 are wiring patterns 130 and 131 (not shown in FIG. 2) made of an Al film formed on an insulating film 129 such as a silicon oxide film on the substrate 121, respectively. And mechanically connected to the substrate 121 via a leg portion 122 composed of two individual leg portions 122a and 122b having a rising portion rising from the substrate 121. Similarly, the fixed end (the end portion in the −X direction) of the beam portion 125 is connected to the substrate 121 via two wiring patterns (not shown) made of an Al film formed on the insulating film 129 on the substrate 121. It is mechanically connected to the substrate 121 via a leg portion 123 composed of two individual leg portions 123a and 123b having a rising portion that rises from the bottom. As described above, the free ends of the beam portions 124 and 125 are mechanically connected by the connection portion 126, and the fixed end sides of the beam constituent portions 132 and 134 are mechanically connected by the connection portion 127. Therefore, in the present embodiment, the beam portions 124 and 125 and the connection portions 126 and 127 constitute a movable portion having a cantilever structure as a whole. In the present embodiment, the substrate 121, the fixed electrode 128, and the insulating film 129 form a fixed portion.
[0051]
The beam portion 124 has two beam constituent portions 132 and 133 mechanically connected in series in the X-axis direction between the fixed end and the free end of the movable portion. The beam forming part 132 is configured in a strip shape extending in the X-axis direction in a plan view as viewed from the Z-axis direction. As shown in FIG. 2, the beam forming portion 133 is configured in a band plate shape and extends mainly in the X-axis direction in a plan view as viewed from the Z-axis direction, but in the Y-axis direction at a position on the −X side. It has a bent shape. The beam constituent portion 132 on the fixed end side (−X side) is a leaf spring portion that can bend in the Z-axis direction, whereas the beam constituent portion 133 on the free end side (+ X side) is in the Z-axis direction (substrate 121). Side and the opposite side) and a rigid portion having substantial rigidity against bending in other directions.
[0052]
The beam forming portion 132 has three layers in which the lower SiN film 141, the intermediate Al films 142 and 143, and the SiN film 144 as the upper protective film are stacked (however, the gap between the Al films 142 and 143 is 2). Layer) and is configured to act as a leaf spring. Although the Al film 142 and the Al film 143 are formed in the same layer, as shown in FIG. 2, they are formed with a slight gap in the Y-axis direction and are electrically separated from each other. This is because the Al film 142 is used as a wiring to the movable electrode for electrostatic force, and the Al film 143 is used as a wiring for forming a current path for Lorentz force. Almost no current flows in the wiring for electrostatic force, while a relatively large current flows in the wiring for Lorentz force. Therefore, in order to reduce the electrical resistance of the wiring for Lorentz force, the Al film 142 is formed with a narrow width, The Al film 143 is formed wide.
[0053]
The beam constituting portion 133 has three layers in which a lower SiN film 141, intermediate Al films 142, 143, and an SiN film 144 serving as an upper protective film, which are continuously extended from the beam constituting portion 132, are stacked (however, In the gap between the Al films 142 and 143, the thin film is composed of two layers. However, the above-described rigidity is given to the beam constituting portion 133 by forming the ridge portions 149 and 150 described later.
[0054]
Although FIG. 3 shows that the beam component 132 is not curved in the Z-axis direction, the beam component 132 is actually stressed in the films 141 to 144 in a state where no drive signal is supplied. Is curved upward (on the opposite side of the substrate 121, in the + Z direction). Such a curved state can be realized by appropriately setting the film formation conditions of the films 141, 142, and 144. On the other hand, the beam constituting portion 133 is not substantially curved in the Z-axis direction regardless of whether or not a drive signal is supplied, and is not bent due to the stress of the films 141 to 144 by having the above-described rigidity. Always maintain a flat state. Thus, the beam component 132 and the beam component 133 have different curved / non-curved states in a state where the beam 124 is not subjected to force.
[0055]
In the present embodiment, the leg portion 122 is configured by continuously extending the SiN films 141 and 144 and the Al films 142 and 143 constituting the beam constituting portion 132, and has two individual leg portions 122a and 122b. is doing. The leg portion 122 has two individual leg portions 122a and 122b because the wiring for electrostatic force and the wiring for Lorentz force are separated, and the Al film 142 and the Al film 143 are formed on the substrate 121. This is because the wiring patterns 130 and 131 are electrically connected to each other. The Al film 142 is electrically connected to the wiring pattern 130 through an opening formed in the SiN film 141 in the individual leg 122a. The Al film 143 is electrically connected to the wiring pattern 131 through an opening formed in the SiN film 141 in the individual leg portion 122b. In addition, in order to reinforce the strength of the leg portion 122, the upper portion of the leg portion 122 has a mouth shape so that the protruding strip portion 151 collectively surrounds the individual leg portions 122 a and 122 b in a plan view as viewed from the Z direction. It is formed in a shape.
[0056]
The beam part 125 and the leg part 123 have the completely same structure as the beam part 124 and the leg part 122, respectively. The beam constituting portions 134 and 135 constituting the beam portion 125 correspond to the beam constituting portions 132 and 133 constituting the beam portion 124. The individual leg portions 123a and 123b constituting the leg portion 123 correspond to the individual leg portions 122a and 122b constituting the leg portion 122, respectively. Further, on the upper portion of the leg portion 123, a ridge portion 152 corresponding to the above-described ridge portion 151 is formed.
[0057]
The connecting portion 127 is composed of a two-layer film of SiN films 141 and 144 that continuously extend from the beam constituting portions 133 and 135 as they are. The Al film 142 from the beam constituent portions 133 and 135 does not extend to the connection portion 127, and no electrical connection is made at the connection portion 127.
[0058]
In the present embodiment, in order to collectively give rigidity to the beam constituting portions 133 and 135 and the connecting portions 126 and 127, as shown by a broken line in FIG. A ridge portion 149 is formed so as to circulate, and a ridge portion 150 is formed so as to circulate toward the inner peripheral side of the collective region. The projecting portions 149 and 150 reinforce the beam constituting portions 133 and 135 and have rigidity. The beam components 133 and 135 are not substantially curved in the Z-axis direction regardless of whether or not a drive signal is supplied, and are not bent by the stress of the films 141 to 144 by having the above-described rigidity. Always maintain a flat state.
[0059]
The connection part 126 is configured by continuously extending the SiN films 141 and 144 and the Al films 142 and 143 constituting the beam constituting parts 133 and 135 as they are. The connecting portion 126 is provided with a mirror 12 made of Au, Ni or other metal as a driven body.
[0060]
The portion of the Al film 142 in the connection portion 126 is also used as an electrostatic force movable electrode (second electrode portion). In a region on the substrate 121 facing the movable electrode, an electrostatic force fixed electrode 128 made of an Al film is formed. Although not shown in the drawing, the Al film constituting the fixed electrode 128 also extends as a wiring pattern. By using the Al film together with the wiring pattern 130, the Al film in the connection portion 126 that serves as both the fixed electrode 128 and the movable electrode is used. A voltage (voltage for electrostatic force) can be applied between the membrane 142.
[0061]
On the other hand, as can be seen from the above description, the Al film 143 causes the beam configuration part 132 → the beam configuration part 133 → the connection part 126 → the beam configuration part 135 → the beam from the wiring pattern 131 below the individual leg part 122b of the leg part 122. A current path is formed through the component 134 to the wiring pattern (not shown) below the individual leg 123b of the leg 123. Of these current paths, the current path along the Y-axis direction at the connecting portion 126 is a portion that generates a Lorentz force in the Z-axis direction when placed in a magnetic field in the X-axis direction. Accordingly, when the permanent magnet 5 shown in FIG. 1 is used and placed in a magnetic field in the X-axis direction and a current (Lorentz force current) is passed through the current path, the Lorentz force (drive) is applied to the Al film 143 in the connection portion 126. Force) acts in the Z direction. Whether the direction of the Lorentz force is the + Z direction or the −Z direction is determined by the direction of the Lorentz force current.
[0062]
As can be seen from the above description, in the present embodiment, the movable portion formed by the beam portions 124 and 125 and the connection portions 126 and 127 is compared with the fixed portion including the substrate 121, the fixed electrode 128, and the insulating film 129. It can move up and down (in the Z-axis direction). In other words, in the present embodiment, the movable portion includes an upper position where the movable portion attempts to return by the spring force of the beam constituting portions 132 and 134 constituting the leaf spring, and a lower position where the connecting portion 126 contacts the fixed electrode 128. You can move between. In the upper position, the distance between the movable electrode of the movable part (the Al film 142 in the connection part 126) and the fixed electrode 128 of the fixed part is widened, and the electrostatic force that can be generated between them is reduced or eliminated. At the lower position, the distance between the movable electrode of the movable part (the Al film 142 in the connection part 126) and the fixed electrode 128 of the fixed part is narrowed, and the electrostatic force that can be generated between the two is increased.
[0063]
Since the movable part returns to the upper position by the spring force or the like, in the following description, returning the movable part to the upper position may be referred to as latch release. On the other hand, since the movable portion is held at the lower position by the electrostatic force against the spring force, in the following description, holding the movable portion at the lower position may be referred to as a latch. is there.
[0064]
In the present embodiment, by controlling the voltage between the electrodes and the current for Lorentz force, the mirror 12 is held at the upper position (on the opposite side to the substrate 121) and the mirror 12 is on the lower side (on the substrate 121 side). It can be held. In the present embodiment, such control is performed as will be described later.
[0065]
In the present embodiment, as shown in FIG. 10, optical switches composed of mirrors 12 and microactuators 111 that drive the mirrors 12 are arranged on a plurality of substrates 121 in a two-dimensional matrix, and these constitute an optical switch array. ing. In the present embodiment, as shown in FIG. 2, the beam constituent parts 133, 135 have a shape that is bent in the Y-axis direction at a position on the −X side in a plan view seen from the Z-axis direction. As shown in FIG. 10, when the plurality of microactuators 111 are two-dimensionally arranged on the substrate 121, the beam portions 124 and 125 are bent in the Y-axis direction. The arrangement density can be increased. FIG. 10 is a schematic plan view schematically showing an optical switch array used in the optical switch system according to the present embodiment.
[0066]
In the present embodiment, the SiN film 144 as a protective film is formed over the entire surface of the movable part and the leg part, but the SiN film 144 may not be formed.
[0067]
FIG. 11 is an electric circuit diagram showing the optical switch array used in the present embodiment. The single optical switch shown in FIGS. 2 to 9 includes one capacitor (corresponding to a capacitor formed by the fixed electrode 128 and the movable electrode (the Al film 142 in the connection portion 126)), 1 It can be regarded as one coil (corresponding to the Al film 143 in the connection portion 126). In FIG. 11, the capacitors and coils of the optical switch of m rows and n columns are denoted as Cmn and Lmn, respectively. For example, the capacitors and coils of the optical switch (in the first row and the first column) in the upper left in FIG. 11 are denoted as C11 and L11, respectively. In the present embodiment, the left electrode in FIG. 11 of each capacitor is a fixed electrode, and the right electrode in FIG. 11 is a movable electrode. However, it goes without saying that the electrical connection relationship between the fixed electrode and the movable electrode may be switched for any one or more capacitors.
[0068]
In FIG. 11, nine optical switches are arranged in 3 rows and 3 columns to simplify the description. However, the number of optical switches is not limited at all, and the principle is the same even when, for example, an optical switch having 100 rows and 100 columns is provided. Even if the number of optical switches is the same, the number of rows and columns need not be the same, and there is no need for a matrix arrangement. For example, when the number of optical switches is nine, the arrangement may be one row and nine columns, and when the number of optical switches is 16, any arrangement of four rows and four columns, one row and sixteen columns, and two rows and eight columns. But you can.
[0069]
As shown in FIG. 11, the optical switch array used in this embodiment includes a first plurality of terminal groups composed of a plurality of terminals CD1 to CD3 and a second terminal composed of a plurality of terminals CU1 to CU3. A third terminal group including a group and a plurality of terminals L0 to L3 is provided. These terminals CD1 to CD3, CU1 to CU3, L0 to L3 are external connection terminals for connection to the external control circuit 6 in FIG. In the present embodiment, the electrical connection shown in FIG. 11 is achieved by the wiring patterns 130 and 131 under the individual leg portions 122a and 122b and the wiring pattern (not shown) under the individual leg portions 123a and 123b. It has been realized. The terminals CD1 to CD3, CU1 to CU3, L0 to L3 can be configured, for example, by using part of these wiring patterns as electrode pads. Note that one of the wiring pattern 130 under the individual leg portion 122a and the wiring pattern under the leg portion 123a is not necessarily used.
[0070]
In FIG. 11, the number of terminals CD1 to CD3 of the first terminal group is three as is the number of rows of the optical switch, and the number of terminals CU1 to CU3 of the second terminal group is the number of columns of the optical switch. There are also three. However, the number of terminals in the first and second terminal groups does not necessarily have to be the same as the number of rows and columns of the optical switch, and for example, the following conditions (a) to may be satisfied. That is, (a) For each microactuator 111, the fixed electrode 128 of the microactuator 111 is electrically connected to one terminal of one of the first and second terminal groups. And (b) with respect to each microactuator 111, the movable electrode of the microactuator 111 is connected to the other terminals of the first and second terminal groups. Electrically connected to any one of the other terminal groups and not electrically connected to the other terminals of the first and second terminal groups, (c) for each microactuator 111, One terminal of the first or second terminal group electrically connected to the fixed electrode 128 of the microactuator 111 and the macro A combination with one terminal of the first or second terminal group electrically connected to the movable electrode of the black actuator 111 is unique to the microactuator 111; (d) the first At least one terminal of the terminal group is electrically connected in common to the fixed electrode 128 or the movable electrode of two or more microactuators 111 of the plurality of microactuators 111 mounted on the optical switch array. (E) At least one terminal of the second terminal group is a fixed electrode 128 or a movable electrode of two or more microactuators 111 of the plurality of microactuators 111 mounted on the optical switch array. In addition, each condition of being electrically connected in common may be satisfied.
[0071]
As an example satisfying the conditions (a) to (e), in the example shown in FIG. 11, the fixed electrode 128 of the capacitors C11, C12, and C13 in the first row is electrically connected to the terminal CD1 of the first terminal group. Connected to each other and not electrically connected to other terminals. The fixed electrodes 128 of the capacitors C21, C22, C23 in the second row are electrically connected in common to the terminal CD2 of the first terminal group, and are not electrically connected to the other terminals. The fixed electrodes 128 of the capacitors C31, C32, and C33 in the third row are electrically connected in common to the terminal CD3 of the first terminal group, and are not electrically connected to the other terminals. Thus, in the example shown in FIG. 11, the fixed electrode 128 of the microactuator 111 of the row is electrically connected in common for each row. The movable electrodes of the capacitors C11, C21, C31 in the first column are electrically connected in common to the terminal CU1 of the second terminal group, and are not electrically connected to the other terminals. The movable electrodes of the capacitors C12, C22, C32 in the second row are electrically connected in common to the terminal CU2 of the second terminal group, and are not electrically connected to the other terminals. The movable electrodes of the capacitors C13, C23, and C33 in the third row are electrically connected in common to the terminal CU3 of the second terminal group, and are not electrically connected to the other terminals. As described above, in the example shown in FIG. 11, the movable electrodes of the microactuators 111 in the corresponding column are electrically connected in common to each column.
[0072]
In FIG. 11, the coils L11, L21, L31 in the first row are connected in series, one end of which is connected to the terminal L1 and the other end is connected to the terminal L0. The second row of coils L12, L22, and L32 are connected in series, with one end connected to the terminal L2 and the other end connected to the terminal L0. The third row of coils L13, L23, and L33 are connected in series, with one end connected to the terminal L3 and the other end connected to the terminal L0.
[0073]
The coils L11, L21, L31 in the first row have their current directions so that the directions of the Lorentz forces generated in these coils L11, L21, L31 are the same when a current is passed between the terminals L1, L0. Connected together. The same applies to the coils L12, L22, L32 in the second row and the coils L13, L23, L33 in the third row. In the present embodiment, when a current flows in the direction from the terminals L1, L2, L3 to the terminal L0 (the current in this direction is a positive current), the current path for Lorentz force of the microactuator 111 is Lorentz. The force is set to work downward.
[0074]
Thus, in the example shown in FIG. 11, the current path for the Lorentz force of the microactuator 111 in each row is electrically connected in series so that the Lorentz force in the same direction is generated when energized. It is connected. However, in the present invention, for each row, the current path for Lorentz force of the microactuator 111 in the row may be electrically connected in series so as to generate the Lorentz force in the same direction when energized. In the present invention, for example, only the coils L11 and L21 are electrically connected in series between the terminals L1 and L0, and the coil L31 is electrically connected to a terminal added separately from the terminal L1. Good.
[0075]
In the example shown in FIG. 11, the terminal L0 is shared, but if the current capacity of the wiring pattern near the terminal L0 is insufficient, the terminal L0 may be divided into a plurality.
[0076]
Note that the optical switch array used in this embodiment does not include an address circuit, a column selection switch, a row selection switch, or the like, as shown in FIG.
[0077]
The optical switch array used in the present embodiment can be manufactured by using a semiconductor manufacturing technique such as film formation and patterning, etching, and sacrificial layer formation / removal. For example, as disclosed in Patent Document 1, the mirror 12 is formed with a recess corresponding to the mirror 12 in a resist, and then Au, Ni, or other metal 38 to be the mirror 12 is formed by electrolytic plating. It can be formed by growing and then removing the resist.
[0078]
In the present embodiment, the external control circuit 6 in FIG. 1 is connected to the terminals CD1 to CD3, CU1 to CU3, L0 to L3, and independently controls the potentials of the terminals CD1 to CD3, CU1 to CU3. At the same time, by independently controlling the currents flowing through the terminals L1 to L3, the optical path switching state of each optical switch of the optical switch array is controlled. The external control circuit 6 responds to the optical path switching state command signal and supplies the control signal for realizing the optical path switching state indicated by the optical path switching state command signal to the terminals CD1 to CD3 and CU1 to CU3 and the terminal L1. ˜L3 is supplied as a current flowing through L3 to realize the optical path switching state. The specific circuit configuration of the external control circuit 6 is apparent from the operation example described below.
[0079]
FIG. 12 shows an example of a potential chart that the external control circuit 6 applies to the terminals CD1 to CD3 and CU1 to CU3, and a current chart that flows through the coils via the terminals L1 to L3. In the example shown in FIG. 12, the external control circuit 6 applies one of the two potentials Vh and Vm1 to the terminals CD1 to CD3 of the first terminal group, and supplies the terminals CU1 to CU3 of the second terminal group. Gives one of two potentials Vm2 and VL. Here, the potentials Vh, Vm1, Vm2, and VL satisfy the relationship of Vh> Vm1 ≧ Vm2> VL. Either one of currents I1 (current in a direction in which a downward Lorentz force is generated) or -I2 (current in a direction in which an upward Lorentz force is generated) flows through each terminal L1 to L3, or the current is short. Not (no current).
[0080]
In the example shown in FIG. 12, before time t1, the potentials of the terminals CD1 to CD3 are set to Vh, the potentials of the terminals CU1 to CU3 are set to VL, and no current flows through the terminals L1 to L3. It is assumed that all the actuators 111 are in a latch-released state (a state where the movable part is positioned at the upper position).
[0081]
Between time t1 and time t2, a current I1 is supplied to the terminals L1, L2, and L3, and the movable parts of all nine actuators 111 are directed downward (on the substrate 121 side, that is, between the fixed electrode 128 and the movable electrode). In the direction of narrowing). As a result, the distance between the fixed electrode 128 and the movable electrode of all the actuators 111 becomes narrow, and when the electrostatic force between both electrodes exceeds a certain value, the movable part of all the actuators 111 is moved to the lower position by the electrostatic force. Is latched on.
[0082]
Between time t3 and time t4, the potential of the terminal CD1 is lowered from Vh to Vm1, the potential of the terminal CU1 is raised from VL to Vm2, and a current −I2 is supplied to the terminal L1. As a result, the voltage between the electrodes of the capacitor C11 in FIG. 11 decreases from Vh-VL to Vm1-Vm2. As the voltage between the electrodes of the capacitor C11 decreases, the electrostatic force between both electrodes of the capacitor C11 also decreases. On the other hand, the Lorentz force due to the current -I2 acts in the direction of separating the fixed electrode and the movable electrode. Here, in the direction in which the Lorentz force and the spring force are separated from each other, the electrostatic force is in the direction in which the force is attracted. When the force in the direction in which the Lorentz force is separated is set to be stronger than the force in the direction in which the force is attracted, the latch is released. And the movable electrode is pulled apart.
[0083]
Further, between time t3 and time t4, the voltage between both electrodes of the capacitors C12 and C13 is Vm1-VL. Since no current flows through the terminals L2 and L3, no Lorentz force is generated in the coils L12 and L13 of the microactuator 111 corresponding to the capacitors C12 and C13. Therefore, if the electrostatic force generated by the voltage difference Vm1-VL is set to be larger than the spring force, the latch of the microactuator 111 corresponding to the capacitors C12 and C13 is maintained.
[0084]
Furthermore, between time t3 and time t4, the voltage between both electrodes of the capacitors C21 and C31 is Vh−Vm2. Since the current -I2 flows through the terminal L1, an upward Lorentz force is generated in the coils L21 and L31 of the microactuator 111 corresponding to the capacitors C21 and C31. Therefore, if the electrostatic force generated by the voltage Vh−Vm2 is set to be larger than the sum of the Lorentz force and the spring force, the latch of the microactuator 111 corresponding to the capacitors C21 and C31 is maintained.
[0085]
Therefore, only the microactuator 111 corresponding to the capacitor C11 is released from time t3 to time t4.
[0086]
As from time t3 to time t4, only the microactuator 111 corresponding to the capacitor C22 is released from time t5 to time t6, and only the fixed and movable electrodes of C33 are released from time t7 to time t8. The latch is released.
[0087]
Up to this point, the initial mirror arrangement of the optical switch in which the latches of the microactuators 111 corresponding to the capacitors C11, C22, and C33 are released and the latches of the other microactuators 111 are maintained is completed.
[0088]
Further, a procedure for changing a part of the mirror arrangement from the initial arrangement will be described.
[0089]
Between time t9 and time t10, a current I1 flows through the terminal L1, and the movable portion of the microactuator 111 corresponding to the capacitor C11 moves downward (on the substrate 121 side, that is, the interval between the fixed electrode 128 and the movable electrode is narrowed). Direction). As a result, the distance between the fixed electrode 128 and the movable electrode of the actuator 111 corresponding to the capacitor C11 becomes narrow, and when the electrostatic force between both electrodes exceeds a certain value, the electrostatic force causes the actuator 111 corresponding to the capacitor C11 to move. The movable part is latched at the lower position.
[0090]
Between time t11 and time t12, a current I1 is supplied to the terminal L2, and the movable portion of the actuator 111 corresponding to the capacitor 22 moves downward (on the substrate 121 side, that is, the direction in which the interval between the fixed electrode 128 and the movable electrode becomes narrower ). As a result, the distance between the fixed electrode 128 and the movable electrode of the actuator 111 corresponding to the capacitor C22 becomes narrow, and when the electrostatic force between both electrodes exceeds a certain value, the electrostatic force of the actuator 111 corresponding to the capacitor C22 is generated by the electrostatic force. The movable part is latched at the lower position.
[0091]
Between time t13 and time t14, the voltage at the terminal CD2 is lowered from Vh to Vm1, the potential at the terminal CU1 is raised from VL to Vm2, and a current −I2 is allowed to flow through the terminal L1. As a result, the voltage between the electrodes of the capacitor C21 in FIG. 11 decreases from Vh-VL to Vm1-Vm2. As the voltage between the electrodes of the capacitor 21 decreases, the electrostatic force between both electrodes of the capacitor C21 also decreases. On the other hand, the Lorentz force due to the current -I2 acts in the direction of separating the fixed electrode and the movable electrode. Here, in the direction in which the Lorentz force and the spring force are separated from each other, the electrostatic force is in the direction in which the force is attracted. When the force in the direction in which the Lorentz force is separated is set to be stronger than the force in the direction in which the force is attracted, the latch is released. And the movable electrode is pulled apart. At this time, the latches of the microactuators 111 corresponding to other capacitors are maintained in the same manner as from the time t1 to the time t2.
[0092]
Between time t15 and time t16, the voltage at the terminal CD1 is lowered from Vh to Vm1, the potential at the terminal CU2 is raised from VL to Vm2, and a current -I2 is supplied to the terminal L2. As a result, the voltage between the electrodes of the capacitor C12 in FIG. 11 decreases from Vh-VL to Vm1-Vm2. As the voltage between the electrodes of the capacitor 12 decreases, the electrostatic force between both electrodes of the capacitor C12 also decreases. On the other hand, the Lorentz force due to the current -I2 acts in the direction of separating the fixed electrode and the movable electrode. Here, in the direction in which the Lorentz force and the spring force are separated, the electrostatic force is in the direction in which the force is attracted. When the force in the direction in which the Lorentz force is separated is set to be stronger than the force in the direction in which the force is attracted, the latch is released. And the movable electrode is pulled apart. At this time, the latches of the microactuators 111 corresponding to other capacitors are maintained in the same manner as from the time t1 to the time t2.
[0093]
This completes the change in the mirror arrangement of the optical switch, in which the latches of the microactuators 111 corresponding to the capacitors C21, C12, and C33 are released and the latches of the other microactuators 111 are maintained.
[0094]
From the above operation explanation, it can be seen that a desired optical path switching state can be appropriately realized.
[0095]
Next, driving conditions related to the above-described operation will be described.
[0096]
Here, the following voltages are defined for nine microactuators 111 corresponding to nine sets of capacitors and coils in FIG.
[0097]
First, the latch release voltage when there is no Lorentz force current -I2 is set to V0. This voltage V0 is released when the voltage between the fixed electrode and the movable electrode in the latched state is lowered without passing the current for Lorentz force through the coil, so that the spring force becomes larger than the electrostatic force and the latch is released. Voltage between electrodes (absolute value). Since the voltage V0 may have a different value for each of the nine microactuators 111, the maximum value is defined as V0max and the minimum value is defined as V0min.
[0098]
Next, let VA be the latch release voltage when there is a Lorentz force current -I2. This voltage VA is the sum of the spring force and the Lorentz force from the electrostatic force when the Lorentz force current -I2 is passed through the coil to reduce the voltage between the fixed electrode and the movable electrode in the latched state. This is the interelectrode voltage (absolute value) at which the latch is released by increasing. Since the voltage VA may have a different value for each of the nine microactuators 111, the maximum value is defined as VAmax and the minimum value is defined as VAmin.
[0099]
In the driving example shown in FIG. 12, the latches of some microactuators 111 are released and the latches of other microactuators 111 are maintained depending on the voltage condition, for example, between time t3 and time t4. In order to establish this situation for the nine microactuators 111, the following equations 3 to 5 are satisfied.
[0100]
[Equation 3]
Vm1-Vm2 <VAmin
[0101]
[Expression 4]
Vm1-VL> V0max
[0102]
[Equation 5]
Vh−Vm2> VAmax
[0103]
Expression 3 is a latch release condition, for example, a condition for releasing the latch of the microactuator 111 corresponding to the capacitor C11 between time t3 and time t4 in FIG. Equation 4 is a latch maintaining condition, for example, a condition for maintaining the latch of the microactuator 111 corresponding to the capacitor C12 between time t3 and time t4 in FIG. Equation 5 is another latch maintaining condition, for example, a condition for maintaining the latch of the microactuator 111 corresponding to the capacitor C21 between time t3 and time t4 in FIG.
[0104]
In the example shown in FIG. 11, the coil of the microactuator 111 in the corresponding column is connected in series for each column. Instead, the coil of the microactuator 111 in the corresponding row is connected in series for each row. In this case, V0max in Equation 4 may be replaced with VAmax, and VAmax in Equation 5 may be replaced with V0max.
[0105]
Furthermore, in the application of the optical switch, it is desired that the moving speed of the mirror 12 is high. Therefore, it is preferable that the period between time t3 and time t4 in FIG. For this purpose, the moving speed of the movable electrode must be increased. When the latch is released, the movable electrode moves by spring force + Lorentz force−electrostatic force. Therefore, when the Lorentz force is constant, the fastest is when the electrostatic force is zero. The Lorentz force is preferably larger within the allowable ranges of both current capacity and heat dissipation.
[0106]
In order to reduce the electrostatic force to 0, Vm1 = Vm2 = Vm ′ may be set. At this time, Equations 3 to 5 become the following Equations 6 to 8, respectively.
[0107]
[Formula 6]
0 <VAmin
[0108]
[Expression 7]
Vm′−VL> V0max
[0109]
[Equation 8]
Vh−Vm ′> VAmax
[0110]
Equation 6 always holds because VAmin is a positive value. When Equation 7 and Equation 8 are rewritten, the following Equation 9 is obtained.
[0111]
[Equation 9]
Vh−VAmax> Vm ′> VL + V0max
[0112]
As an example of actually measured values of the prototyped element, the values of the voltages are values such as V0max = 6V, V0min = 5V, VAmax = 8V, and VAmin = 7V. Substituting these into Equation 9, the following Equation 10 is obtained.
[0113]
[Expression 10]
Vh-8> Vm '> VL + 6
[0114]
As can be seen from Equation 10, Vm ′ may be higher than VL by V0max, that is, 6 V or more, and Vh may be higher than Vm by VAmax, that is, 8 V or more.
[0115]
In the present embodiment, the external control circuit 6 in FIG. 1 indicates that the microactuator 111 having the optical path switching state command signal is unlatched (that is, the movable part is switched from the lower position to the upper position). In this case, the electrostatic force voltage and the Lorentz force current are changed in synchronization with the command signal. At this time, in order to release the latch in the shortest time after such a command signal is generated, the voltage between the movable electrode and the fixed electrode is changed immediately after the input of the command signal, and at the same time, the current in the current path is also changed. Most preferably, -I2 begins to flow. Therefore, in the example shown in FIG. 12, for example, at time t3, the potential of the terminal CD1 is changed from Vh to Vm1, and the potential of the terminal CU1 is changed from VL to Vm2. Is starting to flow. The transition from the unlatched state to the latched state is the same, but in this case, since there is no voltage change as shown in FIG. 12, it is only necessary to flow the Lorentz force current -I2 in synchronization with the command signal (for example, , See time t11 in FIG. 12).
[0116]
According to the present embodiment, when the distance between the movable electrode and the fixed electrode of the microactuator 111 is large (when the movable part is moved from the upper position to the lower position), the microactuator 111 is caused by the Lorentz force. Is moved downward (for example, from time t9 to time t10 in FIG. 12). Therefore, the movable range of the movable plate 21 can be expanded without applying a high voltage to increase the electrostatic force or impairing downsizing. Further, after the movable part of the microactuator 111 is latched to the lower position by the electrostatic force, the Lorentz force current is cut off (for example, from time t10 to time t11 in FIG. 12), and only by the electrostatic force. The movable part is held at the lower position. Therefore, power consumption can be reduced.
[0117]
As described above, according to the present embodiment, since the electrostatic force and the Lorentz force are skillfully used, the movable range of the movable portion can be expanded without applying a high voltage or impairing downsizing. And power consumption can be reduced.
[0118]
Here, the comparative example compared with this Embodiment is demonstrated. FIG. 13 is an electric circuit diagram showing an optical switch array of the optical switch system according to this comparative example. 13, elements that are the same as or correspond to those in FIG. 11 are given the same reference numerals, and redundant descriptions thereof are omitted. The difference between this comparative example and this embodiment is that, in this embodiment, the coils of the microactuator 111 in each row are connected in series for each row, whereas in the comparative example, it is shown in FIG. Thus, one end of the coils L11, L21, L31 in the first row is electrically connected in common to the terminal L1, and one end of the coils L12, L22, L32 in the second row is electrically connected in common to the terminal L2. One end of the coils L13, L23, L33 in the third row is electrically connected in common to the terminal L3, and the other ends of all the coils are electrically connected in common to the terminal L0. That is, in the comparative example, the coils of the row are connected in parallel for each row. Except for the points described above, this comparative example is configured similarly to the present embodiment.
[0119]
Also in the case of this comparative example, the same operation as in this embodiment is realized by applying the potential or current shown in FIG. 12 to each terminal as in this embodiment.
[0120]
However, in the comparative example shown in FIG. 13, for example, since three coils L11, L21, and L31 are connected in parallel between the terminals L1 and L0, the amount of current flowing through the terminal L1 is applied to the terminal L1 in the present embodiment. It will be three times the amount of current flowing. That is, according to the present embodiment, the amount of current flowing through each of the terminals L1, L2, and L3 (and therefore the wiring patterns in the vicinity thereof) is reduced to 1/3, as compared with the case of this comparative example. And the amount of flowing current can be greatly reduced. Therefore, according to the present embodiment, a sufficient Lorentz force can be generated even when the current capacity is largely restricted, which is very advantageous in terms of downsizing and the like.
[0121]
Further, according to the present embodiment, as shown in FIG. 11, since a plurality of coils are connected in series, one end of each coil is connected in common to one terminal for external connection, and each coil The number of terminals for connecting coils (terminals for Lorentz force) can be greatly reduced as compared with the case where the other ends of the coils are individually connected to one external connection terminal. In this embodiment, an address circuit (X address decoder, Y address decoder) or the like for selecting a coil is not mounted.
[0122]
Furthermore, according to the present embodiment, as shown in FIG. 11, one electrode of the capacitor in the row is electrically connected in common to each row, and the other electrode of the capacitor in the row for each column. Are electrically connected in common, the capacitor connection terminals (electrostatic force terminals) are compared to the case where the other electrode of each capacitor is individually connected to one external connection terminal. The number of terminals) can be greatly reduced. In this embodiment, an address circuit (X address decoder, Y address decoder) or the like for selecting a capacitor is not mounted.
[0123]
If an address circuit is used, the number of external connection terminals can be reduced. However, in that case, since an address circuit or the like made of CMOS or the like is mounted on the substrate 121, (1) a high breakdown voltage MOS or the like must be used. Since the planar dimensions increase, the actuator dimensions also increase. (2) Since the optical switch array manufacturing process increases by the MOS manufacturing process, the cost increases. (3) After MOS manufacturing If the planarization is not sufficiently performed, the shape of the base is transferred to the shape of the MEMS fabricated thereon, which may cause an abnormal operation, resulting in the problem that the cost of the planarization process is added. . On the other hand, in the present embodiment, since an address circuit or the like is not mounted on the optical switch array, such a problem does not occur.
[0124]
Further, according to the present embodiment, when the movable part of the microactuator 111 is switched from the lower position to the upper position (when latch is released), the current − that generates an upward Lorentz force in the coil (the Lorentz force current path) I2 is flowing (for example, from time t3 to time t4 in FIG. 12). Therefore, compared with the case where the movable portion returns to the upper position only by the spring force, the movable portion returns to the upper position at a higher speed, and the operation speed is increased.
[0125]
Furthermore, according to the present embodiment, when the movable part of the microactuator 111 is switched from the lower position to the upper position (when the latch is released), the electrostatic force is compared to the case where the movable part is held at the lower position. Is decreased (when Vm1> Vm2) or disappears (when Vm1 = Vm2) (for example, from time t3 to time t4 in FIG. 12). ). Therefore, the force for returning the movable part to the upper position is increased by the amount not reduced by the electrostatic force, so that the movable part returns to the upper position at a higher speed, and the operation speed is increased.
[0126]
[Second Embodiment]
[0127]
FIG. 14 shows the potential applied by the external control circuit 6 to the terminals CD1 to CD3 and CU1 to CU3 and the coils via the terminals L1 to L3 in the optical switch system according to the second embodiment of the present invention. FIG. 12 shows an example of a timing chart of the current flowing through the capacitor, corresponding to FIG.
[0128]
The difference between the present embodiment and the first embodiment is that, in the first embodiment, the external control circuit 6 has a DC voltage as the interelectrode voltage of the capacitor in each period as shown in FIG. In the present embodiment, the potential of the fixed electrode and the movable electrode is controlled so as to be applied, whereas in this embodiment, as shown in FIG. It is only the point which controls the electric potential of a fixed electrode and a movable electrode so that it may be applied. In FIG. 14, the movement of the movable electrode of each microactuator 111 at each time is the same as in FIG.
[0129]
In this embodiment, the potentials applied to the fixed electrodes (potentials applied to the terminals CD1, CD2, CD3) are pulse waveforms having the same phase and a duty of 50%, and amplitudes in the positive and negative directions centering on the ground level. It swings symmetrically at Vh ′ or Vm. The potentials applied to the movable electrodes (potentials applied to the terminals CU1, CU2, CU3) are pulses having the same phase but opposite in phase to those applied to the terminals CD1, CD2, CD3, and the duty is 50%. There is a symmetrical swing with amplitude Vh ′ or Vm in the positive and negative directions around the ground level.
[0130]
The voltage between the electrodes of the capacitor is 2 × Vh ′ when the potential of the movable electrode and the potential of the fixed electrode are both amplitude Vh ′, Vm + Vh ′ when one is amplitude Vh ′ and the other is amplitude Vm, and both are amplitude Vm Is 2 × Vm.
[0131]
Therefore, the equations corresponding to Equations 3 to 5 are as shown in Equations 11 to 13 below.
[0132]
## EQU11 ##
2 × Vm <VAmin
[0133]
[Expression 12]
Vm + Vh '> V0max
[0134]
[Formula 13]
Vm + Vh ′> VAmax
[0135]
Naturally, since VAmax> V0max, Expression 12 is automatically satisfied if Expression 13 is satisfied.
[0136]
Furthermore, since the amplitude Vm is set to 0 in order to make the operation speed the fastest, substituting Vm = 0 into the equations 11 and 13, respectively, yields the following equations 14 and 15.
[0137]
[Expression 14]
0 <VAmin
[0138]
[Expression 15]
Vh '> VAmax
[0139]
Since Expression 14 always holds, the amplitude Vh ′ may be set so as to satisfy Expression 15.
[0140]
As in the present embodiment, when the potential is supplied as shown in FIG. 14, the same operation as that when the potential is supplied as shown in FIG. 12 is realized.
[0141]
In the present embodiment, since there is no direct current component in the drive pulse, the charge-up phenomenon of the insulator supporting the movable electrode can be prevented. If charge up occurs, the voltage that the insulator is charged up overlaps the applied voltage, and the voltage difference between the fixed electrode and the movable electrode changes, so normal operation cannot be performed. Such a possibility disappears and is preferable.
[0142]
Needless to say, according to the present embodiment, other advantages similar to those of the first embodiment can be obtained.
[0143]
In the present embodiment, the terminals CD1 to CD3 and CU1 to CU3 are given potentials that change in a pulse shape with time in each period, but instead, the terminals CD1 to CD3 and CU1 in each period. A potential changing in a sine wave shape with respect to time may be given to CU3. Also in this case, the same advantages as in the present embodiment can be obtained.
[0144]
[Third Embodiment]
[0145]
FIG. 15 and FIG. 16 are schematic cross-sectional views schematically showing main parts of an optical switch system according to the third embodiment of the present invention. FIG. 15 shows a state in which the mirror 12 is held on the upper side and advances into the optical path, and FIG. 16 shows a state in which the mirror 12 is held on the lower side and retracts from the optical path. In FIGS. 15 and 16, the structure of the microactuator 111 is greatly simplified. FIG. 17 is a schematic perspective view schematically showing a part of the optical waveguide substrate 190 in FIGS. 15 and 16.
[0146]
This embodiment is different from the first embodiment only in that an optical waveguide substrate 190 is provided as shown in FIGS. 15 and 16.
[0147]
In the present embodiment, as shown in FIG. 17, the optical waveguide substrate 190 has four optical waveguides 191 to 194 that propagate light to be switched. The optical waveguide substrate 190 has a groove 196 having a width of, for example, about several tens of μm at the center, and end surfaces 191a, 192a, 193b, and 194b of the optical waveguides 191 to 194 are exposed on the side surfaces of the groove 196. The distance between the end face 191a and the end face 192a and the distance between the end face 193b and the end face 194b are designed to be a distance that can be covered by the reflecting surface of the mirror 12, as shown in FIGS.
[0148]
As shown in FIGS. 15 and 16, the optical waveguide substrate 190 is installed on the substrate 121 of the microactuator 111, and the space between the waveguide substrate 190 and the substrate 121 and the space in the groove 196 communicating with the waveguide substrate 190. Further, a refractive index matching liquid 202 is enclosed. Of course, the refractive index matching liquid 202 does not necessarily need to be sealed, but when the refractive index matching liquid is used, the loss of the light beam becomes smaller. The substrate 121 and the optical waveguide substrate 190 are aligned so that the mirror 12 can be inserted into the groove 196.
[0149]
FIGS. 15 to 17 show that the optical waveguide substrate 190 has one intersection of the optical waveguides. However, in practice, the optical waveguides are formed in the optical waveguide substrate 190 in a two-dimensional matrix. Thus, the intersections of the optical waveguides are arranged in a two-dimensional matrix, and accordingly, a plurality of microactuators 111 are arranged in a two-dimensional manner on the substrate 121, and the mirrors 12 positioned at the respective intersections of the optical waveguides are individually It is configured to be driven by the microactuator 111.
[0150]
When the mirror 12 is positioned below the end faces 193b and 194b of the optical waveguides 193 and 194 by the control described above, for example, when light enters from the end face 193a of the optical waveguide 193, the optical waveguide 193 is provided. The light propagating through the light is emitted from the end surface 193b, is incident on the end surface 192a of the optical waveguide 192 as it is, propagates through the optical waveguide 192, and is emitted from the end surface 192b. For example, when light is incident from the end surface 191 b of the optical waveguide 191, the light propagated through the optical waveguide 191 is emitted from the end surface 191 a, enters the end surface 194 b of the opposite optical waveguide 194 as it is, and propagates through the optical waveguide 194. Then, the light is emitted from the end surface 194a.
[0151]
On the other hand, when the mirror 12 is positioned so as to cover the end faces 193b and 194b of the optical waveguides 193 and 194 by the control described above, for example, when light is incident from the end face 193a of the optical waveguide 193, the light The light propagated through the waveguide 193 is emitted from the end face 193b, reflected by the mirror 12, incident on the end face 194b of the optical waveguide 194, propagated through the optical waveguide 194, and emitted from the end face 194a. Further, for example, when light is incident from the end surface 191b of the optical waveguide 191, the light propagated through the optical waveguide 191 is emitted from the end surface 191a, reflected by the mirror 12, and incident on the end surface 192a of the optical waveguide 192. It propagates through the waveguide 192 and exits from the end face 192b.
[0152]
Also in this embodiment, the same advantages as those in the first embodiment can be obtained. In the present invention, the third embodiment may be modified similarly to the case where the first embodiment is modified to obtain the second embodiment.
[0153]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.
[0154]
For example, the embodiment described above is an example in which the microactuator device according to the present invention is applied to an optical switch system. However, the use of the microactuator device according to the present invention is not limited to the optical switch system.
[0155]
【The invention's effect】
As described above, according to the present invention, the movable range of the movable part can be expanded without applying a high voltage or impairing downsizing, and the power consumption can be reduced. It is possible to provide a microactuator array that can reduce the amount of current flowing, and a microactuator device, an optical switch array, and an optical switch system using the microactuator array.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of an optical switch system including an optical switch array according to a first embodiment of the present invention.
FIG. 2 is a schematic plan view schematically showing one optical switch as a unit element constituting the optical switch array used in the optical switch system according to the first embodiment of the present invention.
3 is a schematic cross-sectional view taken along line X11-X12 in FIG.
4 is a schematic sectional view taken along line X13-X14 in FIG.
5 is a schematic cross-sectional view taken along line X15-X16 in FIG.
6 is a schematic sectional view taken along line Y11-Y12 in FIG.
7 is a schematic sectional view taken along line Y13-Y14 in FIG.
8 is a schematic sectional view taken along line Y15-Y16 in FIG.
9 is a schematic cross-sectional view taken along line Y17-Y18 in FIG.
FIG. 10 is a schematic plan view schematically showing an optical switch array used in the optical switch system according to the first embodiment of the present invention.
FIG. 11 is an electric circuit diagram showing an optical switch array used in the optical switch system according to the first embodiment of the present invention.
FIG. 12 is a timing chart of potentials and currents applied to each terminal by the external control circuit in the optical switch system according to the first embodiment of the present invention.
FIG. 13 is an electric circuit diagram showing an optical switch array of an optical switch system according to a comparative example.
FIG. 14 is a timing chart of potentials and currents applied to each terminal by the external control circuit in the optical switch system according to the second embodiment of the present invention.
FIG. 15 is a schematic cross-sectional view schematically showing a main part of an optical switch system according to a third embodiment of the present invention in a state where a mirror is held on the upper side.
FIG. 16 is a schematic cross-sectional view schematically showing a main part of an optical switch system according to a third embodiment of the present invention in a state where a mirror is held on the lower side.
17 is a schematic perspective view schematically showing a part of the optical waveguide substrate in FIGS. 15 and 16. FIG.
[Explanation of symbols]
1 Optical switch array
2 Optical fiber for optical input
3, 4 Optical fiber for optical output
5 Magnet
6 External control circuit
12 Mirror
CD1-CD3, CU1-CU3, L0-L3 terminals
111 Microactuator
121 substrate
128 Fixed electrode

Claims (12)

A microactuator array comprising a plurality of microactuators,
Each of the microactuators includes a movable part provided so as to be movable with respect to the fixed part, a first electrode part provided on the fixed part, and the first electrode part provided on the movable part, A second electrode portion capable of generating an electrostatic force between the first electrode portion and a voltage between the first electrode portion and a direction in which the movable portion is provided in the movable portion and disposed in a magnetic field, and the movable portion moves by the electrostatic force A current path generated by energizing a Lorentz force that moves the movable part in the same direction as
A microactuator characterized in that the current paths of two or more microactuators of the plurality of microactuators are electrically connected in series so as to generate a Lorentz force in the same direction when energized. Array. The plurality of microactuators are arranged in a two-dimensional matrix,
The current path of the microactuator of the column or row is electrically connected in series so that a Lorentz force in the same direction is generated when energized for each row or column. Item 2. The microactuator array according to Item 1. For each row, one of the first and second electrode portions of the microactuator of the row is electrically connected in common,
3. The microactuator array according to claim 1, wherein the other of the first and second electrode portions of the microactuator in the row is electrically connected in common to each row. With respect to each of the microactuators, the movable part can move between a first position where the electrostatic force increases and a second position where the electrostatic force decreases and attempts to return to the second position. So that a spring force is generated,
With respect to each of the microactuators, the current path has a first direction that moves the movable part from the second position to the first position, or a second opposite to the first direction, depending on the direction of energization. 4. The microactuator array according to claim 1, wherein the microactuator array is provided so as to generate a Lorentz force in a direction.   The microactuator array according to claim 4, a magnetic field generation unit that generates the magnetic field, and the potential of the first and second electrode units of each microactuator and the current flowing through the current path are controlled, And a control unit that performs control to switch the position of the movable part of each microactuator.   The control unit relates to at least one microactuator of the plurality of microactuators, and the first and second electrode units are configured such that the movable part is held at the first position by the electrostatic force. When the movable part is switched from the second position to the first position, a current having a direction corresponding to the first direction of the Lorentz force is passed through the current path to control the movable part. 6. The microactuator device according to claim 5, wherein the current is interrupted after the portion is held at the first position by the electrostatic force.   The control unit relates to at least one microactuator of the plurality of microactuators, and the first and second electrode units are configured such that the movable part is held at the first position by the electrostatic force. When the movable portion is switched from the first position to the second position, a current is supplied to the current path in a direction corresponding to the second direction of the Lorentz force. The microactuator device according to claim 5 or 6.   The control unit relates to at least one microactuator of the plurality of microactuators, and the first and second electrode units are configured such that the movable part is held at the first position by the electrostatic force. When the movable part is switched from the first position to the second position, the electrostatic force is reduced as compared with the case where the movable part is held at the first position. Alternatively, the microactuator device according to any one of claims 5 to 7, wherein the potential of the first and second electrode portions is controlled so that the electrostatic force disappears. The control unit relates to at least one microactuator of the plurality of microactuators, in synchronization with a command signal indicating a command to switch the movable unit from the first position to the second position, and the voltage change between the first and second electrode portions, the claims and the energization current to the current path of the direction corresponding to the second orientation of the Lorentz force, characterized in that it starts simultaneously The microactuator device according to any one of 5 to 8.   The said control part controls the electric potential of the said 1st and 2nd electrode part so that an alternating voltage may be applied between the said 1st and 2nd electrode part, The Claim 5 thru | or 9 characterized by the above-mentioned. The microactuator device according to any one of the above.   An optical switch array comprising: the microactuator array according to claim 1; and a mirror provided on each of the movable parts of the plurality of microactuators.   An optical switch system comprising: the microactuator device according to any one of claims 5 to 11; and a mirror provided in each of the movable parts of the plurality of microactuators.

Images