JP2019199876A - Shape memory alloy thin-film actuator baseboard - Google Patents

Abstract

To provide an autofocus drive actuator which is extremely thin in thickness and large in generation force in order to achieve a small height of a camera module.SOLUTION: In a shape memory alloy thin-film actuator baseboard, a substantially-polygonal plate-shaped baseboard movable part 102 holding a moving object (a lens or an imaging element), and a substantially-polygonal baseboard fixing frame 103 larger than the baseboard movable part are connected to each other by only shape memory alloy thin films, and individual shape memory alloy thin films 101a, 101b, 101c and 101d have linear shapes extending along one side of two polygons in a space between the two polygons. By applying a bias force to the baseboard movable part 102 from the outside, the moving object can be moved in a vertical direction with respect to the baseboard fixing frame 103 (autofocus function), and by independently moving the individual shape memory alloy thin films, an inclination from the vertical direction also becomes possible (camera shake correction function).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shape memory alloy thin film actuator suitable for use in a drive mechanism for autofocus or camera shake correction of a small camera module, particularly a mobile phone camera module.

  Currently, VCM (voice coil motor) and piezoelectric elements are the mainstream of auto focus or camera shake correction drive mechanisms that are currently in circulation, and there is a demand for further miniaturization and weight reduction of these drive mechanisms in order to make mobile phones thinner. (PTL 1).

  On the other hand, shape memory alloy thin film actuators using MEMS (Micro Electro Mechanical Systems) technology are expected as small and powerful actuators. There are two types of actuators: bridge type, diaphragm type, and cantilever type. The bridge type and diaphragm type have a large force for use in the tensile deformation mode, but the displacement is small, and the cantilever type is used in the bending deformation mode. Therefore, it is pointed out that the displacement is large but the force is weak (Non-patent Document 1).

  As an example of using the shape memory alloy thin film actuator for the autofocus mechanism, the cantilever type is known in Patent Documents 2, 3, and 4, and the bridge type is known in Patent Documents 5, 6, and 7.

  The shape memory characteristics of a single shape memory alloy thin film have been investigated in Non-Patent Document 2, and a Ti—Ni—Cu alloy thin film produced by sputtering exhibits characteristics superior to Ti—Ni alloys on the market. It has been reported.

  It is known that the shape change of the shape memory alloy can be directly monitored by knowing the electric resistance, and an actuator driver that maintains a constant shape by controlling the current for energization heating while measuring the electric resistance (Patent Document 8) ) Is also open to the public. For this reason, it is known that when a shape memory alloy is used for a camera drive mechanism, a separate sensor for detecting the position of the lens is not required.

JP 2013-254184 A JP 2011-109853 A JP 2009-89306 A Japanese Patent Laid-Open No. 2019-28439 JP 2009-196060 A JP 2011-001824 A International Publication Number WO2011 / 001972 Japanese Patent Laid-Open No. 2007-21754

A. Ishida et al., Smart Mater. Struct. 16 (2007) 1672. A. Ishida et al., J. MoI. Alloys and Compounds, 577S (2013) S184

A camera module such as a mobile phone is desired to have a low profile (Patent Document 1). However, it is difficult to reduce the thickness of a drive mechanism using a piezoelectric element or VCM (voice coil motor) to 1 mm or less in view of the complexity of the structure.
Patent Documents 2, 3 and 4 disclose a mechanism for moving a movable part by a cantilever type shape memory alloy thin film actuator. However, the cantilever actuator is known to have a weak force, and it is difficult to expect a large generated force.
On the other hand, Patent Document 5 reports an example in which a bridge-type shape memory alloy thin film actuator is applied to an autofocus mechanism. Here, since the shape memory alloy thin film actuator expands and contracts in a direction perpendicular to the optical axis, A complicated mechanism for changing the displacement in the direction of the optical axis is required.

  In Patent Document 6, a mechanism is disclosed in which a part holding a lens is brought into contact with and moved in the approximate center of a shape memory alloy stretched over two places of a fixed frame, but a thin film is used for the shape memory alloy. Then, there is a problem such as breakage because the tip of the protruding portion of the component directly hits the thin film. Further, in Patent Document 7, a shape memory alloy extends from a corner of the fixed frame, is joined to a member that moves while holding a lens at the next corner, and then bent into an L shape to face the opposite corner of the fixed frame. Although a mechanism for moving the lens by the shape memory alloy reaching the part is disclosed, in this case, since the movable part is supported at two points, it is expected that the movable part is easily swayed and the support of the movable part becomes unstable.

  The present invention solves the above-described problems, and provides an autofocus mechanism, a camera shake correction mechanism, and a camera unit using the same, which are extremely thin, highly responsive, and have a large generated force.

In order to achieve the above object, the shape memory alloy thin film actuator substrate of the present invention has the following configuration.
[1] A substantially polygonal plate-like movable part holding a moving object and a substantially polygonal fixed frame having an opening larger than the movable part are connected only by a shape memory alloy thin film, and the shape The memory alloy thin film is located in a space between two polygonal gaps of the movable part and the fixed frame, and is parallel to the polygonal side of the movable part and the polygonal side of the fixed frame, A shape memory alloy thin film actuator substrate having a linear shape extending along one side of a polygon of a fixed frame.
[2] The shape memory alloy thin film extending along one side of the polygon of the fixed frame is composed of a plurality of shape memory alloy thin films extending in parallel along the one side. Actuator board. (See Figure 2)

[3] In the shape memory alloy thin film actuator substrate, a direction from the part where the shape memory alloy thin film is joined to the fixed frame to the part joined to the movable part is defined as the direction of the shape memory alloy thin film. The shape memory alloy thin film installed in parallel with two adjacent sides sharing the vertex of the polygon of the fixed frame has directions opposite to each other, according to [1] or [2] Shape memory alloy thin film actuator substrate. (See Figure 3)
[4] The shape memory alloy thin film actuator substrate according to [3], wherein a length of the shape memory alloy thin film is 1/3 or more and 2/3 or less of a length of each side.
[5] In the plurality of shape memory alloy thin films extending in parallel along the one side, the shape memory has a direction from a portion where the shape memory alloy thin film is joined to the fixed frame to a portion where the movable portion is joined. The shape memory alloy thin film actuator substrate according to [2], wherein the shape memory alloy thin film actuator substrate includes the same number of shape memory alloy thin films having a direction opposite to the direction of the shape memory alloy thin film. (See Figure 6)
[6] Both ends of the shape memory alloy thin film extending along each polygon side of the fixed frame are joined to a fixed frame side joint provided near the apex of the opening of the fixed frame, and the shape memory The shape memory alloy thin film actuator substrate according to [1] or [2], wherein a substantially center portion of the alloy thin film is joined to a movable portion side joint provided at a substantially center of each polygon side of the movable portion. (See Figure 5)

[7] The fixed frame has a rectangular frame shape, and the movable portion that fits in the opening of the fixed frame has a shape in which a protrusion serving as a joint portion of the shape memory alloy thin film is provided in the vicinity of the vertex of the rectangular plate. Any one of [1] to [5], wherein the movable portion is connected to the fixed frame via the shape memory alloy thin film at four or more joint portions separated from each other. Shape memory alloy thin film actuator substrate. (See Figure 1)
[8] The fixed frame has a hexagonal frame shape, and has a protrusion that becomes a joint of the shape memory alloy thin film in the vicinity of the apex on the opening side, and the movable part is in the vicinity of the apex of the hexagonal plate. And the movable part is connected to the fixed frame via the shape memory alloy thin film at three or more joints separated from each other. The shape memory alloy thin film actuator substrate according to any one of [1] to [5], wherein: (See Figure 4)

[9] The shape memory alloy thin film actuator substrate according to any one of [1] to [8], wherein the movable portion and the fixed frame are made of a Si substrate.
[10] The shape memory alloy thin film actuator substrate according to any one of [1] to [8], wherein the movable portion and the fixed frame are made of a metal substrate.
[11] Insulating or improving adhesion between the shape memory alloy thin film and the substrate forming the movable part and the fixed frame at the joint of the shape memory alloy thin film on the movable part side and the fixed frame side. The shape memory alloy thin film actuator substrate according to any one of [1] to [10], wherein an intermediate layer is provided.
[12] The shape memory alloy thin film actuator substrate according to [11], wherein the intermediate layer is an oxide of a substrate material.

[13] The shape memory alloy thin film has Ti—50 atomic% to 55 atomic% Ti, 10 atomic% to 20 atomic Cu, the balance being Ni and inevitable impurities. The shape memory alloy thin film actuator substrate according to any one of [1] to [12], which is a Ni—Cu alloy thin film.
[14] The shape memory alloy thin film has a compositional element of Ti of 45 atomic% or more and less than 50 atomic%, atomic percentage of 10 + 1.6 × (50−Ti atomic%) exceeding 20 + 1.6 × (50 A shape according to any one of [1] to [12], wherein the shape is a Ti—Ni—Cu alloy thin film in which Cu is equal to or less than (atomic% of Ti), and the balance is Ni and inevitable impurities. Memory alloy thin film actuator substrate.
[15] In the shape memory alloy thin film, Ti— containing 50 atomic% to 55 atomic% of Ti, 5 atomic% to 10 atomic% of Cu, the balance being Ni and inevitable impurities The shape memory alloy thin film actuator substrate according to any one of [1] to [12], which is a Ni—Cu alloy thin film.

[16] The shape memory alloy thin film actuator according to any one of [1] to [15], wherein the moving object is a lens or an imaging device, or a part incorporating the lens or the imaging device. substrate.
[17] The shape memory alloy thin film actuator substrate according to [16], wherein the moving object is a lens or a part incorporating the lens, and the movable part has an opening window for securing an optical path.

[18] The movable portion of the shape memory alloy thin film actuator substrate according to any one of [1] to [17] or the moving object held by the movable portion with respect to the surface of the fixed frame A drive mechanism in which a vertically displaceable bias spring is contacted or joined directly or via a spacer, and the movable portion is displaced perpendicularly to the surface of the fixed frame.
[19] The bias spring is disposed on the opposite side of the surface on which the shape memory alloy thin film is formed with respect to the movable portion, and the movable portion is on the opposite side of the surface on which the shape memory alloy thin film is formed. The drive mechanism according to [18], wherein the drive mechanism is pressed from the side.
[20] The drive mechanism according to [18] or [19], wherein the bias spring is the shape memory alloy thin film actuator substrate according to any one of [1] to [15].

[21] The electrical resistance of the shape memory alloy thin film is controlled by energizing the shape memory alloy thin film of the drive mechanism according to any one of [18] to [20] with a drive current from the autofocus control circuit. The camera module is configured so that it can be given the function of autofocus.
[22] A wiring including the shape memory alloy thin film on the shape memory alloy thin film actuator substrate built in the camera module according to [21] is provided on one end of the fixed frame via the movable portion. A camera module configured to energize the other end.
[23] The drive current from the image stabilization control circuit is energized independently to each of the shape memory alloy thin films of the shape memory alloy thin film actuator substrate of the drive mechanism according to any one of [18] to [20]. By doing so, the movable part is inclined, and the camera module characterized by the above-mentioned.
[24] A camera-equipped mobile phone or a small camera comprising the camera module according to any one of [21] to [23].

According to the invention [1] configured as described above, since the length of the shape memory alloy thin film can be increased to a length close to each side of the polygon, a bridge type shape memory alloy having a large generated force but a small displacement. While compensating for the shortcomings of the thin film actuator, it is possible to obtain a large generation force that cannot be obtained with the cantilever type shape memory alloy thin film actuator.
According to the invention [2] having the above configuration, by dividing one wide shape memory alloy thin film into a plurality of narrow shape memory alloy thin films, the cooling rate is increased, and the shape memory alloy thin film actuator Response speed can be improved.
According to the inventions [3] to [6] having the above-described configuration, it is possible to prevent the internal movable portion from rotating as the shape memory alloy thin film contracts.
According to the inventions [4] to [6] having the above-described configuration, the movable part can be supported at four points and can be stably held.
According to the invention [7] having the above configuration, the wafer can be subdivided into devices by dicing. Furthermore, by supporting the movable part at four or more points, it is possible to obtain a stable movement without rolling.
According to the invention [8] having the above configuration, the movable portion can be supported at three points, and a stable movement can be obtained.

According to the invention [9] having the above configuration, a Si semiconductor process can be used, and the shape memory alloy thin film actuator substrate according to [1] to [8] can be mass-produced.
According to the invention [10] having the above-described configuration, it is possible to use a metal plate such as copper, aluminum, titanium, or chromium that is less expensive than Si. By using a metal that is more ductile than Si, which exhibits brittle mechanical properties, damage to the substrate can be prevented.
According to the invention [11] having the above configuration, it is possible to improve the insulation between the shape memory alloy thin film and the substrate and reduce the power consumption. In addition, the adhesion between the substrate and the shape memory alloy thin film can be improved.
According to the invention [12] having the above configuration, an insulating film can be easily obtained by oxidation of the substrate material.

According to the inventions [13] to [15] having the above-described configuration, a shape using a shape memory alloy thin film having a transformation temperature higher than that of a Ti—Ni alloy, a lower temperature hysteresis, a larger generated force, and an excellent response. A memory alloy thin film actuator substrate is obtained.
According to the inventions [13] and [14] having the above-described configuration, the generated force is remarkably larger than that of the Ti—Ni—Cu alloy wire, and the sputtering is difficult to control the composition because the composition dependency of the characteristics is small. A shape memory alloy thin film actuator substrate using a shape memory alloy thin film exhibiting the above characteristics (large generating force, high responsiveness, high transformation temperature) is obtained.
According to the invention [13] having the above structure, there is provided a shape memory alloy thin film actuator substrate using a shape memory alloy thin film having a transformation temperature higher than that of the thin film of the invention [14] having the above structure and excellent in reliability. can get.

According to the invention [16] having the above configuration, it is possible to perform autofocus or camera shake correction by moving a lens or an image sensor.
According to the invention [17] having the above configuration, the optical path of the lens can be secured.
According to the invention [18] having the above configuration, the bias spring having a displacement perpendicular to the fixed frame of the shape memory alloy thin film actuator substrate is pressed against the movable portion of the shape memory alloy thin film actuator, thereby being mounted on the movable portion. A drive mechanism for moving the target object in a direction perpendicular to the surface of the fixed frame of the shape memory alloy thin film actuator substrate can be provided.
According to the invention [19] having the above-described configuration, it is possible to improve the peelability of the shape memory alloy thin film and the substrate at the movable portion side joint portion.
According to the invention [20] having the above configuration, the stroke of the drive mechanism can be increased.

According to the invention [21] having the above-described configuration, it is possible to provide an autofocus mechanism that precisely controls the autofocus position using the autofocus control circuit.
According to the invention [22] having the above configuration, the shape memory alloy thin film can be easily heated, and an autofocus mechanism having a simple structure can be provided.
According to the invention [23] having the above-described configuration, the camera shake correction mechanism that can tilt the movable portion from the vertical direction of the surface of the fixed frame by independently changing the height of each joint portion on the movable portion side. Can be provided.
According to the invention [24] having the above configuration, the thickness of the camera-equipped mobile phone or the small camera can be reduced.

FIG. 1 is a schematic diagram of a shape memory alloy thin film actuator substrate showing an embodiment of the present invention, and shows a plan view of a shape memory alloy thin film actuator substrate in which four shape memory alloy thin films are arranged along a rectangular side. Yes. FIG. 2A is a schematic view of a shape memory alloy thin film actuator substrate showing an embodiment of the present invention. The shape memory alloy thin film along each side of FIG. 1 is divided into a plurality of narrow shape memory alloy thin films. The top view of the arrange | positioned shape memory alloy thin film actuator board | substrate is shown. FIG. 2B is a plan view of a bias spring that suppresses the rotation of the movable portion. FIG. 3A is a schematic view of a shape memory alloy thin film actuator substrate showing an embodiment of the present invention, and the direction of the shape memory alloy thin film along each side (from the fixed frame side joint to the movable part side joint). FIG. 2 is a plan view of a shape memory alloy thin film actuator substrate in which rotation of a movable portion is suppressed by alternately changing (defined as a direction) between two adjacent sides. FIG. 3 (b) shows a plan view of a shape memory alloy thin film actuator substrate for the purpose of individually operating the shape memory alloy thin film described in FIG. 3 (a). FIG. 4 is a schematic view of a shape memory alloy thin film actuator substrate showing an embodiment of the present invention, and shows a plan view of a shape memory alloy thin film actuator substrate in which the shape of the fixed frame is hexagonal. FIG. 5 is a schematic view of a shape memory alloy thin film actuator substrate showing an embodiment of the present invention, and shows a plan view of the shape memory alloy thin film actuator substrate in which the shape memory alloy thin film on each side is joined to the movable part at the center. ing. FIG. 6 is a schematic diagram of a shape memory alloy thin film actuator substrate showing an embodiment of the present invention. Each shape memory alloy thin film along two opposite sides faces each other (from the fixed frame side joint to the movable part side joint). FIG. 2 shows a plan view of a shape memory alloy thin film actuator substrate composed of two shape memory alloy thin films having different directions (directions toward the part). FIG. 7 is a table showing the generated force and stroke (predicted value) of the shape memory alloy thin film actuator substrate of FIGS. FIGS. 8A and 8B are diagrams showing an example of manufacturing a shape memory alloy thin film actuator substrate. FIG. 8A is a crystallization heat treatment by forming a shape memory alloy thin film on a Si substrate, and FIG. 8B is a shape memory using patterning by photoetching. The alloy thin film is etched, (c) shows the fine processing of the Si substrate, and (d) shows the process of forming the wiring material and patterning by photolithography. FIG. 9 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example in which the moving object is an image sensor. FIG. 10 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example where the moving object is a lens. FIG. 11 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example of a component in which a moving object incorporates a lens. FIG. 12 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example in which the shape memory alloy thin film actuator substrate is also used as a bias spring. FIG. 13 shows an example of a camera module using the drive mechanism of FIG. FIG. 13A is a schematic cross-sectional assembly view, and FIG. 13B is a block diagram showing a signal flow. FIG. 14 is a diagram of a mobile phone in which the camera module with an autofocus function of FIG. 13 is incorporated.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 14 of the accompanying drawings.
FIG. 1 is a plan view of the most basic shape memory alloy thin film actuator substrate in which four shape memory alloy thin films 101a, 101b, 101c, and 101d are arranged along four sides of a rectangular substrate movable portion 102 and a substrate fixing frame 103. FIG. One of these shape memory alloy thin films is provided on the fixed frame side joints 106a, 106b, 106c, and 106d on the substrate fixed frame 103, and the other end is provided on the movable portion side in the vicinity of the apex of the rectangular movable substrate portion. The joints 107a, 107b, 107c, and 107d are joined to the substrate movable part 102 to constitute a so-called bridge shape memory alloy thin film actuator. Wirings 105 a, 105 b, 105 c, 105 d, and 105 e are provided on the substrate movable portion 102 and the substrate fixing frame 103 so as to connect the above-described four shape memory alloy thin films.
The lens opening window 104 is a circular window provided at the center of the substrate movable portion 102, and the center portion of the lens opening window 104 is positioned so as to coincide with the optical axis of a lens (not shown). The guide holes 108 a, 108 b, 108 c, 108 d are provided at the four corners of the lens opening window 104 of the substrate movable unit 102, and hold the posture of the substrate movable unit 102.

  One end of the shape memory alloy thin film 101 a is connected to a wiring 105 d also serving as a power feeding terminal provided on the substrate fixing frame 103, and the other end is connected to a wiring 105 b provided on one side of the substrate movable portion 102. One end of the shape memory alloy thin film 101b is connected to the wiring 105b, and the other end is connected to the wiring 105a provided on one side of the substrate fixing frame. One end of the shape memory alloy thin film 101 c is connected to the wiring 105 a, and the other end is connected to the wiring 105 c provided on the opposite side of the substrate movable portion 102. One end of the shape memory alloy thin film 101d is connected to the wiring 105c, and the other end is connected to the wiring 105e installed on the substrate fixing frame also serving as a power feeding terminal. The shape memory alloy thin film and the wiring arranged in this way form one circuit, and when a voltage is applied between the wirings 105d and 105e, the shape memory alloy thin films 101a, 101b, 101c, and 101d are heated by energization, Change at the same time. Therefore, by combining the shape memory alloy thin film actuator substrate shown in FIG. 1 with bias springs 1005a and 1005b as shown in FIG. 10, the lens 1004 fixed at the position of the lens opening window 104 of the substrate movable portion 102 in FIG. It can be moved along the optical axis.

  For example, a silicon substrate, a metal substrate such as copper, aluminum, titanium, or chromium, a resin, or the like can be used as the material of the substrate movable portion 102 and the substrate fixing frame 103. The shape of the substrate movable part 102 is, for example, a rectangular substrate of 6 mm × 6 mm and a thickness of 0.1 mm to 1 mm. The shape of the substrate fixing frame 103 is, for example, a rectangle having an outer side of 10 mm × 10 mm and an inner side of 8 mm × 8 mm and a thickness of 0.1 mm to 1 mm. Note that the materials and shapes of the substrate movable portion 102 and the substrate fixing frame 103 are not limited to these, and appropriate design changes can be made within a range obvious to those skilled in the art.

As the material of the shape memory alloy thin films 101a, 101b, 101c, and 101d, for example, a Ti—Ni—Cu alloy thin film containing 50 atomic% or more and 55 atomic% or less of Ti and 10 atomic% or more and 20 atoms or less of Cu. Although it is good to use, it is not limited to this, The shape memory alloy of a composition which is demonstrated in detail later can be used. The shape of the shape memory alloy thin films 101a, 101b, 101c, and 101d is preferably, for example, a rectangle of 0.8 mm × 6 mm and a thickness of 3 to 10 μm, but is not limited to this, and will be described in detail later. Various shapes can be used.
The shape of the lens opening window 104 is, for example, 3 to 4 mm in diameter.
The wirings 105a, 105b, 105c, 105d, and 105e are made of materials that have low conductivity resistance and good adhesion to the substrate movable portion 102, the substrate fixing frame 103, and the shape memory alloy thin films 101a, 101b, 101c, and 101d. For example, copper, aluminum alloy, silver, gold or the like is used. The thickness of the wirings 105a, 105b, 105c, 105d, and 105e may be any thickness that can supply current necessary for driving the shape memory alloy thin films 101a, 101b, 101c, and 101d, and is preferably 1 to 10 μm, for example. However, the present invention is not limited to this.

  In the apparatus shown in FIG. 1, the four shape memory alloy thin films are oriented in the same direction (the direction from the fixed frame side joints 106a, 106b, 106c, 106d toward the movable part side joints 107a, 107b, 107c, 107d). Therefore, when the shape memory alloy thin film contracts, a torque is generated so that the drive unit rotates counterclockwise. In order to prevent the drive unit from rotating, the substrate movable unit 102 is provided with guide holes 108a, 108b, 108c, and 108d. Guides 906a and 906b as shown in FIG. 9 are stuck in the hole portions to prevent the substrate movable portion from rotating. The guide hole is not necessarily provided in the movable substrate portion 102, and may be attached to the component 1104 that holds the lens as shown in FIG. In the apparatus shown in FIG. 1, the substrate movable portion 102 has a shape memory alloy thin film 101 a connected to a substrate fixing frame at four movable portion side joints 107 a, 107 b, 107 c, and 107 d (four corners in this case) separated from each other. , 101b, 101c, 101d, the substrate movable part can be stably supported by four-point support.

2A is a plan view of a shape memory alloy thin film actuator substrate in which the shape memory alloy thin film along each side of FIG. 1 is divided into a plurality of narrow shape memory alloy thin films. In the figure, the substrate movable portion 202, the substrate fixing frame 203, the lens opening window 204, and the wirings 205a, 205b, 205c, 205d, and 205e are the substrate moving portion 102, the substrate fixing frame 103, and the lens opening window 104 shown in FIG. The wirings 105a, 105b, 105c, 105d, and 105e have the same configuration and operation.
Further, the shape memory alloy thin films 201a1 and 201a2 have the same action as the shape memory alloy thin film 101a shown in FIG. 1, and the width is about 30% to 4.5%. The shape memory alloy thin films 201b1 and 201b2 have the same action as the shape memory alloy thin film 101b shown in FIG. 1, and have a width of approximately 30% to 4.5%. The shape memory alloy thin films 201c1 and 201c2 have the same function as the shape memory alloy thin film 101c shown in FIG. 1 and have a width of approximately 30% to 4.5%. The shape memory alloy thin films 201d1 and 201d2 have the same action as the shape memory alloy thin film 101d shown in FIG. 1, and have a width of approximately 30% to 4.5%.

  In the apparatus configured in this way, cooling is facilitated by dividing one shape memory alloy thin film into a plurality of narrow shape memory alloy thin films, and a bridge is provided between the substrate fixing frame 203 and the substrate movable portion 202. Since the contraction speed of the formed shape memory alloy thin films 201a1, 201a2, 201b1, 201b2, 201c1, 201c2, 201d1, 201d2 is increased, a moving object such as a lens fixed to the lens opening window 204 of the substrate movable portion 202 is removed. It can be moved quickly. FIG. 2A shows a case where one shape memory alloy thin film is divided into two narrow shape memory alloy thin films provided in parallel, but the present invention is limited to two. It may be separated into three or more.

FIG. 2B is a plan view showing an example of a bias spring. As shown in FIG. 10, for example, the bias spring is used together with the movable substrate portion 202 and the substrate fixing frame 203 in FIG. 2A. For example, a flat spring of phosphor bronze or stainless steel is used.
The bias spring is composed of a bias spring fixed frame 211b having a peripheral rectangular frame shape and an inner bias spring movable portion 211a. The bias spring movable portion 211a is joined to the substrate movable portion 202 of the shape memory alloy thin film actuator substrate. The Details of the bias spring will be described later in detail with reference to FIGS. 9, 10, and 11.
The lens opening window 212 is a circular window provided at the center of the bias spring movable portion 211a, and the center of the lens opening window 212 is positioned so as to coincide with the optical axis of the lens (not shown).

  In the apparatus configured as described above, the horizontal position of the bias spring movable portion 211a is restricted by the bias spring fixing frame 211b, and the bias spring movable portion 211a is joined to the substrate movable portion 202 of the shape memory alloy thin film actuator substrate. By doing so, the rotation of the movable substrate portion 202 can be suppressed without providing the guide holes 108a, 108b, 108c, and 108d shown in FIG. When the guide holes 108a, 108b, 108c and 108d are not provided as shown in FIG. 2A, it is not necessary to engage with the guides 906a and 906b as shown in FIG. Work becomes easy.

  In the apparatus shown in FIG. 2, one end of each of the shape memory alloy thin films 201a1 and 201a2, 201b1 and 201b2, 201c1 and 201c2, 201d1 and 201d2 is fixed to the substrate fixing frame 203 at the fixed frame side joints 206a, 206b, 206c, and 206d. The ends are joined to the movable substrate portion 202 at the movable portion side joint portions 207a, 207b, 207c, and 207d. Since the movable portion side joint portions are located away from each other, the substrate movable portion 202 is stabilized with four-point support. Can be supported.

  FIG. 3A is a plan view of a shape memory alloy thin film actuator substrate in which the directions of the four shape memory alloy thin films in FIG. 1 are alternately changed on adjacent sides. In the figure, the shape memory alloy thin films 301a, 301b, 301c, 301d, the substrate movable portion 302, the substrate fixing frame 303, and the lens opening window 304 are the shape memory alloy thin films 101a, 101b, 101c, 101d, the substrate movable shown in FIG. This has the same configuration and function as the portion 102, the substrate fixing frame 103, and the lens opening window 104.

The wiring 305a is provided at one of the four corners of the substrate fixing frame 303, and also serves as a terminal of the shape memory alloy thin films 301a and 301b.
The wiring 305b is provided on the substrate movable part, and one end is connected to the shape memory alloy thin film 301b and the other end is connected to the shape memory alloy thin film 301c.
Similarly, the wiring 305c is on the substrate movable portion 302, and one end is connected to the shape memory alloy thin film 301a and the other end is connected to the shape memory alloy thin film 301d.
The wiring 305d is provided at one of the four corners of the substrate fixing frame 303 and diagonally with the wiring 305a, and also serves as a terminal of the shape memory alloy thin films 301c and 301d.

  In the apparatus configured as described above, the rotation of the movable substrate portion 302 can be prevented. However, when the length of the shape memory alloy thin film is close to the length of the side, the substrate movable portion 302 is supported at only two points, and the support of the substrate movable portion 302 becomes unstable. Therefore, the length of the shape memory alloy thin film is preferably suppressed to about 2/3 or less of the side. By suppressing the length of the shape memory alloy thin film to 2/3 or less, the movable part side joints 307a, 307b, 307c, 307d of the shape memory alloy thin films 301a, 301b, 301c, 301d can be separated from each other, and the substrate is movable. The portion 302 can be stably supported at four points.

FIG. 3B is a plan view of a shape memory alloy thin film actuator substrate in which the shape memory alloy thin film along each side of FIG. In the drawing, the substrate movable portion 322, the substrate fixing frame 323, and the lens opening window 324 have the same configuration and operation as the substrate moving portion 202, the substrate fixing frame 203, and the lens opening window 204 shown in FIG. .
The shape memory alloy thin films 321a, 321b, 321c, 321d have two substantially U-shaped parallel shape memory alloy thin films, the U-shaped base is joined to the substrate movable portion 322, and the U-shaped tip is Bonded to the substrate fixing frame 323 and connected to the wirings 325a and 325b, 325c and 325d, 325e and 325f, and 325g and 325h, respectively.

  In the apparatus configured as described above, the height of the four movable portion side joints can be individually changed by independently operating the shape memory alloy thin film. Can be changed. Such a mechanism can be used as a camera shake correction.

FIG. 4 is a plan view of a shape memory alloy thin film actuator substrate having a hexagonal substrate shape. In the figure, shape memory alloy thin films 401 a, 401 b, 401 c, 401 d, 401 e, 401 f are fixed frame side joints 406 a, 406 b, 406 c, 406 d, 406 e, 406 f, one end of which is provided at the inner edge of the substrate fixing frame 403. The other end of the substrate fixed frame 403 is joined to the substrate movable frame 402 at movable portion side joint portions 407 a, 407 b, 407 c, 407 d, 407 e, and 407 f provided at the hexagonal edge of the substrate movable portion 402.
For example, a silicon substrate is used as the material for the substrate movable portion 402 and the substrate fixing frame 403. The shape of the substrate movable portion 402 is, for example, a hexagonal substrate with a side of 6 mm and a thickness of 0.1 mm to 1 mm. The substrate movable part 402 is provided with three protrusions on the outer corners of the hexagonal substrate, and one end of the shape memory alloy thin film is attached thereto.
The shape of the substrate fixing frame 403 is, for example, a hexagonal substrate having an outer side of 10 mm and an inner side of 8 mm and a thickness of 0.1 mm to 1 mm. The substrate fixing frame 403 is provided with three projections at the inner corners of the hexagonal substrate, and the other end of the shape memory alloy thin film is attached thereto. The outer protruding portion of the substrate movable portion 402 and the inner protruding portion of the substrate fixing frame 403 are provided so as not to interfere with each other.
Note that the materials and shapes of the substrate movable portion 402 and the substrate fixing frame 403 are not limited to this, and appropriate design changes can be made within a range obvious to those skilled in the art.

The lens opening window 404 is a circular window provided in the central portion of the substrate movable portion 402, and the center portion of the lens opening window 404 is positioned so as to coincide with the optical axis of a lens (not shown).
The wiring 405a is provided on one side of the inner protrusion of the substrate fixing frame 403, and one end of the shape memory alloy thin film 401b is attached to the wiring 405a. The wiring 405b is provided on the outer protrusion of the movable substrate portion 402, and the other end of the shape memory alloy thin film 401b and one end of the 401a are attached. The wiring 405c is provided on the inner protrusion of the substrate fixing frame 403, and is attached to the other end of the shape memory alloy thin film 401a and one end of 401f. The wiring 405d is provided on the outer protrusion of the movable substrate portion 402, and is attached to the other end of the shape memory alloy thin film 401f and one end of 401e. The wiring 405e is provided on the inner protrusion of the substrate fixing frame 403, and is attached to the other end of the shape memory alloy thin film 401e and one end of 401d. The wiring 405f is provided on the outer protrusion of the substrate movable part 402, and is attached to the other end of the shape memory alloy thin film 401d and one end of 401c. The wiring 405g is provided on one side of the inner protrusion of the substrate fixing frame 403, and the other end of the shape memory alloy thin film 401c is attached. The wiring 405 a and the wiring 405 g also serve as power supply terminals for the shape memory alloy thin film, and are provided on opposite sides of the same inner protrusion of the substrate fixing frame 403.

  In the apparatus configured as described above, the substrate movable portion 402 is supported at three points, and the substrate movable portion 402 can be stably supported.

  In FIG. 5, shape storage alloy thin films 501 a, 501 b, 501 c, and 501 d are provided along the sides of the substrate movable portion 502 and the substrate fixing frame 503. Both ends of each shape memory alloy thin film 501a, 501b, 501c, 501d are joined to the substrate fixing frame 503 at the fixed frame side joints 506a1 and 506a2, 506b1 and 506b2, 506c1 and 506c2, and 506d1 and 506d2, respectively. The movable part side joints 507a, 507b, 507c, and 507d are joined to the substrate movable part 502 at the approximate center of the thin film. The wirings 505a, 505b, 505c, and 505d are formed on the substrate fixing frame 503, and a combination of 505a and 505c or 505b and 505d can also serve as a power feeding terminal for the shape memory alloy thin film.

  In the apparatus configured as described above, the shape memory alloy thin films 501a, 501b, 501c, and 501d along one side of the substrate movable portion 502 and the substrate fixing frame 503 are substantially a bridge type that is substantially half the length thereof. It is composed of two shape memory alloy thin film actuators, and the generated force can be approximately doubled although the displacement is substantially halved compared to the shape memory alloy thin film actuator for autofocus driving in FIG. Further, the apparatus shown in FIG. 5 has an advantage that the movable portion of the substrate does not rotate when the shape memory alloy thin film contracts. Furthermore, since the movable part side joining parts 507a, 507b, 507c, and 507d are separated from each other, the substrate movable part 502 can be stably moved by four-point support.

FIG. 6A is a plan view of a shape memory alloy thin film actuator substrate in which two shape memory alloy thin films having two opposite sides are formed by two shape memory alloy thin films 601a1 and 601a2 and 601b1 and 601b2, respectively. is there.
One end of each of the shape memory alloy thin films 601a1 and 601a2 and 601b1 and 601b2 is provided in the fixed frame side joints 606a1, 606a2, 606b1, and 606b2, and the other end is provided in the vicinity of the vertex of the rectangular movable substrate 602. The protrusions and the movable part side joints 607a1, 607a2, 607b1, and 607b2 provided at the extending parts are joined to the substrate movable part 602.
The wiring 605 a is formed in an extending portion provided in parallel with the edge of the substrate movable portion 602. The shape memory alloy thin film 601 a 2 is located between the wiring 605 a and one side of the substrate movable portion 602. The shape memory alloy thin film 601a1 is located between the wiring 605a and one side of the substrate fixing frame 603.
The wiring 605b is formed in an extending portion provided in parallel with one side of the substrate movable portion 602 opposite to the wiring 605a. The shape memory alloy thin film 601b2 is located between the wiring 605b and one side opposite to the substrate movable portion 602. In addition, the shape memory alloy thin film 601b1 is located between the wiring 605b and one side opposite to the substrate fixing frame 603.

  In the apparatus configured as described above, the substrate movable portion 602 does not rotate and is supported at four points, so that stable movement can be obtained. In this case, a reinforcing material 611 as shown in FIG. 6B may be attached to the substrate movable portion 602 to reinforce the narrowed portion of the substrate. In FIG. 6A, the shape memory alloy thin film is provided on two sides of the four sides of the rectangle, but a similar shape memory alloy thin film may be provided on the four sides.

  FIG. 7 shows the generated force and stroke of each substrate estimated using the performance prediction formula of the bridge-type shape memory alloy thin film actuator disclosed in Non-Patent Document 1 for the shape memory alloy thin film actuator substrate of FIGS. Show. Using the physical property value (K value) of the Ti—Ni—Cu alloy thin film, assuming the length, thickness, width and number of the shape memory alloy thin film described in the table when one side of the shape memory alloy thin film actuator substrate is 10 mm Thus, the generated force and stroke of the shape memory alloy thin film actuator substrate when a constant bias force was applied to the substrate movable portion were predicted. The values shown in this table are examples. In a bridge-type shape memory alloy thin film actuator, the displacement increases in proportion to the length of the shape memory alloy thin film, and the generated force increases in proportion to the width and thickness. Therefore, a wide range of generated forces and strokes can be obtained by appropriately designing changes as those skilled in the art.

FIG. 8 shows an example of manufacturing a shape memory alloy thin film actuator substrate. In the step shown in FIG. 8A, a Ti—Ni—Cu alloy thin film 801 is formed on a Si wafer 802 by sputtering, and then a crystallization heat treatment is performed at a high temperature of 500 ° C. or higher. In the process shown in FIG. 8B, an unnecessary shape memory alloy thin film is formed by wet etching with HF / HNO ₃ / H ₂ O or electrolytic etching with sulfuric acid / methanol or LiCl / ethanol solution using photolithography technology. remove. In the step shown in FIG. 8C, the Si substrate is finely processed by reactive ion etching using SF ₆ gas. Finally, in a step shown in FIG. 8D, a wiring material 803 such as Cu, Al, Ag, Au is formed by plating or sputtering, and patterning is performed to form a circuit. Here, FIG. 8D corresponds to a cross section of the actuator substrate cut along the shape memory alloy thin film 101a of FIG.

FIG. 8 shows an example of a manufacturing method. For example, a metal substrate such as copper, aluminum, titanium, or chromium, or a resin can be used as the substrate. Compared with silicon having brittle mechanical properties, the use of a metal substrate can prevent the substrate from being damaged. Further, in order to ensure insulation at the fixed frame side joint 804 and the movable part side joint 805, an intermediate layer such as SiO ₂ , Si ₃ N _4, metal oxide or resin is provided between the substrate and the shape memory alloy thin film. May be inserted. Since the Si substrate exhibits the characteristics of the semiconductor, even if the shape memory alloy thin film is directly formed as shown in FIG. 8, most of the current flows through the shape memory alloy thin film, but between the Si substrate and the shape memory alloy thin film. By providing an insulating layer, current can be efficiently passed through the shape memory alloy thin film to reduce power consumption. Moreover, when using a metal for a board | substrate, the insulating layer as an intermediate | middle layer is essential. Furthermore, when a Ti—Ni or Ti—Ni—Cu shape memory alloy thin film is formed directly on a Si substrate, Ni in the shape memory alloy thin film reacts with Si in the substrate at a high crystallization heat treatment temperature. It is known that Ni silicide is made and the shape memory alloy thin film is easily peeled off from the substrate. In order to solve this problem, the adhesion of the shape memory alloy thin film can be improved by sandwiching a thin film of Ag or the like that is not solid-solved with Ni as an intermediate layer between the shape memory alloy thin film and the substrate. These intermediate layers can be formed by thermal oxidation or anodic oxidation of the substrate, film formation by CVD or sputtering, coating by spin coating, or the like before performing sputtering in the step shown in FIG. When an oxide film is formed on a metal substrate by anodic oxidation, a dielectric breakdown occurs when the film thickness is thin, so a film thickness of 100 nm or more is preferable. In addition, the thickness of the Ag thin film for the purpose of improving adhesion is desirably 1 μm or less in order to reduce power consumption.

As shape memory alloy thin films, alloys showing shape memory effects such as Ti—Ni, Ti—Ni—Cu, Ti—Ni—Pd, Ti—Ni—Hf, Ti—Ni—Zr, Cu—Al—Ni alloys, etc. Any thin film may be used, but in particular, a Ti—Ni—Cu alloy thin film containing 50 atomic% to 55 atomic% Ti and 5 atomic% to 20 atomic Cu or 45 atomic% to 50 atomic% Ti. It is preferable to use a Ti—Ni—Cu alloy thin film containing Cu exceeding 10 + 1.6 × (atomic percent of 50-Ti) and not more than 20 + 1.6 × (atomic percent of 50-Ti).
According to the alloy thin film having such a composition, a shape memory alloy thin film having a high transformation temperature, a small temperature hysteresis, a large generating force, and an excellent responsiveness as compared with the Ti—Ni alloy used is usually used. A shape memory alloy thin film actuator can be produced.

Preferably, a Ti—Ni—Cu alloy thin film containing 50 atomic% or more and 55 atomic% or less of Ti and 10 atomic% or more and 20 atoms or less of Cu or 45 atomic% or more and less than 50 atomic% of Ti and atomic% It is preferable to use a Ti—Ni—Cu alloy thin film containing 10 + 1.6 × (50-Ti atomic%) and 20 + 1.6 × (50-Ti atomic%) or less of Cu.
According to the alloy thin film having such a composition, the generated force is remarkably larger than that of the Ti—Ni—Cu alloy wire, and stable characteristics (large force, high) are obtained even in sputtering in which composition control of properties is small and composition control is difficult. A shape memory alloy thin film actuator substrate using a shape memory alloy thin film exhibiting responsiveness and high transformation temperature can be manufactured in large quantities at low cost.

  More preferably, by using a Ti—Ni—Cu shape memory alloy thin film containing 50 atomic% or more and 55 atomic% or less of Ti and more than 10 atomic% and 20 atomic% or less of Cu, the transformation temperature is higher. A shape memory alloy thin film actuator substrate using a shape memory alloy thin film (Non-Patent Document 2) having excellent reliability can be manufactured.

  An example of a drive mechanism configured by combining a shape memory alloy thin film actuator substrate and a bias spring is shown in FIGS. As an embodiment, an example in which the shape memory alloy thin film actuator substrate of FIG. 1 is used is shown, but any of the shape memory alloy thin film actuator substrates of FIGS.

FIG. 9 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example in which the moving object is an image sensor.
The shape memory alloy thin films 901a and 901b are obtained by viewing the shape memory alloy thin films 101a and 101c of FIG. 1 from the side. The shape memory alloy thin films 901a and 901b are bridged between the substrate fixing frame 903 and the substrate movable portion 902, respectively. It constitutes an actuator.
The substrate fixing frame 903 corresponds to the substrate fixing frame 103 in FIG. 1, and the substrate movable portion 902 corresponds to the substrate movable portion 102 in FIG.
The image sensor 904 is a moving object mounted on the substrate movable unit 102, and is configured by a CMOS sensor, a CCD sensor, or the like. The image sensor 904 is fixed to the substrate movable portion 902 with an adhesive or the like.

The bias springs 905 a and 905 b directly apply a force that pushes the substrate movable portion 902 from the surface of the substrate fixing frame 903.
The guides 906a and 906b are formed of resin or the like, and are used through the guide holes 108a, 108b, 108c, and 108d of the actuator substrate of FIG. 1 so that the substrate movable portion 902 does not rotate. However, the guide can be omitted if the configuration is made as shown in FIGS. 2 to 6 so that the substrate movable portion does not rotate. The case 907 is made of resin or the like, and stores the image pickup element at an appropriate position.

  In the apparatus configured as described above, since the shape memory alloy thin films 901a and 901b are easily deformed and extended at room temperature, the substrate movable portion 902 is held at a position in contact with the case 907 by the bias springs 905a and 905b. The On the other hand, when the shape memory alloy thin films 901a and 901b are heated by energization, the substrate movable portion 902 is retracted to a position close to the substrate fixing frame 903 because it contracts to the original shape, so that the moving object can be moved. Autofocus function can be realized.

FIG. 10 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example where the moving object is a lens.
The shape memory alloy thin films 1001a and 1001b are the shape memory alloy thin films 101a and 101c shown in FIG. 1 as viewed from the side. The shape memory alloy thin films 1001a and 1001b are bridged between the substrate fixing frame 1003 and the substrate movable portion 1002, respectively. It constitutes an actuator.
The substrate fixing frame 1003 corresponds to the substrate fixing frame 103 in FIG. 1, and the substrate movable portion 1002 corresponds to the substrate movable portion 102 in FIG.
The lens 1004 is a moving object mounted on the substrate movable unit 102 and is fixed to the substrate movable unit 1002 with an adhesive or the like. As the material of the lens, phenol resin or acrylic resin is used.

  The bias springs 1005a and 1005b apply a force that pushes the substrate movable part 1002 from the surface of the substrate fixing frame 1003 via the spacers 1008a and 1008b. In FIG. 10, bias springs 1005a and 1005b are placed on the side of the substrate movable portion 1002 on which the shape memory alloy thin film is formed (in FIG. 10, the opposite side as viewed from the substrate movable portion 1002), and a bias force is applied. However, in this case, the shape memory alloy thin films 1001a and 1001b have such a force that the shape memory alloy thin films 1001a and 1001b are peeled off from the movable substrate moving portion 1002 at the joints with the movable substrate portion. It is not preferable.

As the bias spring, a flat plate spring or coil spring made of metal such as phosphor bronze or stainless steel can be used. When the bias springs 1005a and 1005b are flat springs (for example, FIG. 2B), spacers 1008a and 1008b are necessary. When a coil spring or a bent spring shown in FIG. 9 is used as a bias spring, no spacer is required. Further, as shown in FIG. 12, a shape memory alloy thin film actuator substrate (comprising 1201c, 1201d, 1202b, and 1203b) can also be used as a bias spring.
The case 1007 is formed of resin or the like, and stores a lens, an actuator substrate, and a bias spring arranged at appropriate positions.
The stopper 1009 is a convex portion formed of resin or the like, and is used to determine the position of the substrate movable portion 1002 when not heated. Note that the substrate movable portion may be directly applied to the case 1007 to be stopped without the stopper.

  In the apparatus configured as described above, since the shape memory alloy thin films 1001a and 1001b are easily deformed at room temperature, the substrate movable portion 1002 is held at a position in contact with the stopper 1009 by the bias springs 1005a and 1005b. On the other hand, when the shape memory alloy thin films 1001a and 1001b are heated by energization, the substrate movable portion 1002 is retracted to a position close to the substrate fixing frame 1003 because it contracts to the original shape, so that the moving object can be moved. Autofocus function can be realized.

FIG. 11 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example of a component in which a moving object incorporates a lens.
The shape memory alloy thin films 1101a and 1101b are obtained by viewing the shape memory alloy thin films 101a and 101c of FIG. 1 from the side. The shape memory alloy thin films 1101a and 1101b are bridged between the substrate fixing frame 1103 and the substrate movable portion 1102, respectively. It constitutes an actuator.
The substrate fixing frame 1103 corresponds to the substrate fixing frame 103 in FIG. 1, and the substrate movable portion 1102 corresponds to the substrate movable portion 102 in FIG.
The lens holding component 1104 is formed of resin or the like and is pressed against the substrate movable portion 1102 by bias springs 1105a and 1105b.

The bias springs 1105 a and 1105 b apply a force that pushes the substrate movable portion 1102 from the surface of the substrate fixing frame 1103 via the lens holding component 1104.
The case 1107 is formed of resin or the like, and stores a lens holding component, an actuator substrate, and a bias spring in appropriate positions.
The lens 1109 is held by a lens holding component 1104.

  In the apparatus configured as described above, since the shape memory alloy thin films 1101a and 1101b are easily deformed at room temperature, the movable substrate portion 1102 is held at a position in contact with the case 1107 by the bias springs 1105a and 1105b. On the other hand, when the shape memory alloy thin films 1101a and 1101b are heated by energization, the substrate movable portion 1102 is retracted to a position close to the substrate fixing frame 1103 because it contracts to the original shape, so that the moving object can be moved. Autofocus function can be realized.

FIG. 12 is a side view of a drive mechanism made by combining the shape memory alloy thin film actuator substrate of FIG. 1 and a bias spring, and shows an example in which the shape memory alloy thin film actuator substrate is also used as a bias spring.
The shape memory alloy thin films 1201a and 1201b (these are the shape memory alloy thin films 101a and 101c of FIG. 1 as viewed from the side) are bridged between the substrate fixing frame 1203a and the substrate movable portion 1202a, respectively. A shape memory alloy thin film actuator is formed. The shape memory alloy thin films 1201c and 1201d are used as bias springs.
The substrate fixing frame 1203a corresponds to the substrate fixing frame 103 in FIG. 1, and the substrate movable portion 1202a corresponds to the substrate movable portion 102 in FIG.
The lens 1204 is a moving object to be mounted on the substrate movable unit 102 and is fixed to the substrate movable unit 1202a with an adhesive or the like.
The case 1205 is formed of resin or the like, and stores a lens, an actuator substrate, and a bias spring arranged at appropriate positions.
The spacers 1206a and 1206b are used by being sandwiched between the movable substrate portions 1202a and 1202b.

In the apparatus configured as described above, since the shape memory alloy thin films 1201a and 1201b are easily deformed at room temperature, the movable substrate portion 1202a is pushed out by the shape memory alloy thin films 1201c and 1201d used as bias springs, and the case 1205 Is held at the position where it abuts. On the other hand, when the shape memory alloy thin films 1201a and 1201b are heated by energization, the substrate movable portion 1202a is retracted to a position close to the substrate fixing frame 1203a because it contracts to the original shape, so that the moving object can be moved. Autofocus function can be realized.
When the shape memory alloy thin film actuator substrate as shown in FIG. 12 is also used as a bias spring, there is an advantage that the stroke of the movable substrate portion 1202a can be increased as compared with the normal bias spring shown in FIGS.

  FIG. 13 shows an example of a camera module using the drive mechanism of FIG. FIG. 13A is a schematic side cross-sectional view of the camera module. By replacing the imaging lens unit 1301 among the components of the conventional camera module with the drive mechanism shown in FIG. 10, a camera module corresponding to the autofocus function can be manufactured.

  FIG. 13B is a block diagram showing a signal flow of the camera module. The autofocus signal output from the imaging unit 1321 is sent to the CPU 1323 of the camera body via the camera module terminal 1322. On the other hand, lens position information instructed from the CPU 1323 based on this information is sent to the actuator driver IC 1324. Two wires extending from the actuator driver IC 1324 are connected to two terminals (105d and 105e in FIG. 1) of the shape memory alloy thin film actuator substrate (FIG. 1) inside the imaging lens unit 1325 (drive mechanism in FIG. 10). In addition, the electrical resistance of the shape memory alloy thin film is measured, and at the same time, the current required for energization heating of the shape memory alloy thin film is controlled so as to maintain the resistance value of the shape memory alloy thin film corresponding to the lens position designated by the main body CPU 1323 To do.

  Although the actuator driver IC is arranged outside the camera module in FIG. 13, the actuator driver IC 1402 may be placed inside the camera module 1401 as shown in FIG. Since the driving mechanism of FIG. 10 can be made thinner than the conventional lens driving mechanism, the thickness of the mobile phone main body 1404 of FIG. 14 can be reduced. A similar effect can be obtained not only in a mobile phone but also in a small camera equipped with the above-described camera module, and the thickness of the apparatus main body can be reduced.

  In the above-described embodiments, various configuration examples are shown as the shape memory alloy thin film actuator substrate and the autofocus mechanism or the camera shake correction mechanism using the shape memory alloy thin film actuator substrate. However, the present invention is not limited to this. It goes without saying that an appropriate design change can be made as a trader.

  According to the shape memory alloy thin film actuator substrate of the present invention, the position of the lens can be changed in a direction perpendicular to the optical axis (autofocus function). Further, if each actuator is moved independently, it can be tilted from the optical axis direction (camera shake correction mechanism).

101a, 101b, 101c, 101d Shape memory alloy thin film 102 Substrate movable part 103 Substrate fixed frame 104 Lens opening windows 105a, 105b, 105c, 105d, 105e Wiring 106a, 106b, 106c, 106d Fixed frame side joints 107a, 107b, 107c, 107d Movable part side joints 108a, 108b, 108c, 108d Guide holes 201a1, 201a2, 201b1, 201b2, 201c1, 201c2, 201d1, 201d2 Shape memory alloy thin film 202 Substrate movable part 203 Substrate fixing frame 204 Lens opening window 205a 205b, 205c, 205d, 205e Wiring 206a, 206b, 206c, 206d Fixed frame side joints 207a, 207b, 207c, 207d Movable part side joints 211a Bias spring movable part 21 1b Bias spring fixing frame 212 Lens opening window 301a, 301b, 301c, 301d Shape memory alloy thin film 302 Substrate movable part 303 Substrate fixing frame 304 Lens opening window 305a, 305b, 305c, 305d Wiring 306a, 306b, 306c, 306d Frame side joints 307a, 307b, 307c, 307d Movable part side joints 321a, 321b, 321c, 321d Shape memory alloy thin film 322 Substrate movable part 323 Substrate fixed frame 324 Lens opening windows 325a, 325b, 325c, 325d, 325e, 325f, 325g, 325h wiring
401a, 401b, 401c, 401d, 401e, 401f Shape memory alloy thin film 402 Substrate movable part 403 Substrate fixing frame 404 Lens opening windows 405a, 405b, 405c, 405d, 405e, 405f, 405g
Wiring 406a, 406b, 406c, 406d, 406e, 406f Fixed frame side joints 407a, 407b, 407c, 407d, 407e, 407f Movable part side joints 501a, 501b, 501c, 501d Shape memory alloy thin film 502 Substrate movable part 503 Substrate Fixed frame 504 Lens opening window 505a, 505b, 505c, 505d Wiring 506a1, 506a2, 506b1, 506b2, 506c1, 506c2, 506d1, 506d2 Fixed frame side joint 507a, 507b, 507c, 507d Movable part side joint 601a1 , 601b1, 601b2 Shape memory alloy thin film 602 Substrate movable part 603 Substrate fixing frame 604 Lens opening window 605a, 605b Wiring 606a1, 606a2, 606b1, 606b2 Fixed frame side joint 60 a1, 607a2, 607b1, 607b2 Movable part side joint 611 Reinforcement material 612 Lens opening window 801 Ti-Ni-Cu shape memory alloy thin film 802 Si substrate 803 Wiring material 804 Fixed frame side joint 805 Movable part side joint 901a, 901b Shape memory alloy thin film 902 Substrate movable part 903 Substrate fixed frame 904 Imaging element 905a, 905b Bias spring 906a, 906b Guide 907 Case 1001a, 1001b Shape memory alloy thin film 1002 Substrate movable part 1003 Substrate fixed frame 1004 Lens 1005a, 1005b Bias spring 1006a , 1006b Guide 1007 Case 1008a, 1008b Spacer 1009 Stopper 1101a, 1101b Shape memory alloy thin film 1102 Substrate movable part 1103 Substrate fixing frame 1104 Lens holding part 1105a, 1105b Bias spring 1106a, 1106b Guide 1107 Case 1108a, 1108b Spacer 1109 Lens 1201a, 1201b, 1201c, 1201d Shape memory alloy thin film 1202a, 1202b Substrate movable part 1203a, 1203b Substrate fixed frame 1204 Lens 1205 Case 1206a, 1206b Spacer 1301 Lens unit 1302 Imaging unit 1303 Flexible substrate 1304 Camera module terminal 1305 Lens 1306 Imaging element 1307 Signal processing LSI
1308 Infrared cut filter 1321 Imaging unit 1322 Camera module terminal 1323 CPU
1324 Actuator Driver IC
1325 Imaging lens unit 1401 Camera module 1402 Actuator driver IC
1403 CPU
1404 Mobile phone body

Claims (24)

A substantially polygonal plate-like movable part holding a moving object and a substantially polygonal fixed frame having an opening larger than the movable part are connected only by a shape memory alloy thin film,
The shape memory alloy thin film is located in a space between two polygonal gaps of the movable part and the fixed frame, and is in a state parallel to the polygonal side of the movable part and the polygonal side of the fixed frame. A shape memory alloy thin film actuator substrate having a linear shape extending along one side of the polygon of the fixed frame.   2. The shape memory alloy thin film actuator substrate according to claim 1, wherein the shape memory alloy thin film extending along one side of the polygon of the fixed frame is composed of a plurality of shape memory alloy thin films extending in parallel along the one side. The shape memory alloy thin film actuator substrate,
When the direction from the part where the shape memory alloy thin film is joined to the fixed frame to the part joined to the movable part is the direction of the shape memory alloy thin film,
The shape memory alloy according to claim 1 or 2, wherein the shape memory alloy thin films installed in parallel to two adjacent sides sharing the vertex of the polygon of the fixed frame have directions opposite to each other. Thin film actuator substrate.   4. The shape memory alloy thin film actuator substrate according to claim 3, wherein a length of the shape memory alloy thin film is not less than 1/3 and not more than 2/3 of the length of each side. A plurality of shape memory alloy thin films extending in parallel along one side of the shape memory alloy thin film has a direction from a portion where the shape memory alloy thin film is bonded to the fixed frame to a portion where the shape memory alloy thin film is bonded to the movable portion. When facing
3. The shape memory alloy thin film actuator substrate according to claim 2, comprising the same number of shape memory alloy thin films having a direction opposite to the direction of the shape memory alloy thin film.   Both ends of the shape memory alloy thin film extending along each polygon side of the fixed frame are joined to a fixed frame side joint provided in the vicinity of the apex of the opening of the fixed frame, and the shape memory alloy thin film The shape memory alloy thin film actuator substrate according to claim 1, wherein a substantially central portion is joined to a movable portion side joint provided at a substantially center of each polygon side of the movable portion.   The fixed frame has a rectangular frame shape, and the movable part that fits in the opening of the fixed frame has a shape with a projection that becomes a joint part of a shape memory alloy thin film near the vertex of a rectangular plate, and the movable frame The shape memory alloy thin film according to any one of claims 1 to 5, wherein the shape memory alloy thin film is connected to the fixed frame via the shape memory alloy thin film at four or more joint portions separated from each other. Actuator board. The fixed frame has a hexagonal frame shape, and has a protrusion that becomes a joint of the shape memory alloy thin film near the apex on the opening side, and the movable part has a shape memory near the apex of the hexagonal plate. It is a shape with a protrusion that becomes the joint of the alloy thin film,
6. The shape memory according to claim 1, wherein the movable portion is connected to the fixed frame via the shape memory alloy thin film at three or more joint portions separated from each other. Alloy thin film actuator substrate.   The shape memory alloy thin film actuator substrate according to claim 1, wherein the movable portion and the fixed frame are made of a Si substrate.   The shape memory alloy thin film actuator substrate according to claim 1, wherein the movable portion and the fixed frame are made of a metal substrate. In the joint part on the movable part side and the fixed frame side of the shape memory alloy thin film,
The shape memory alloy according to any one of claims 1 to 10, wherein an intermediate layer for improving insulation or adhesion is provided between the shape memory alloy thin film and the substrate on which the movable part and the fixed frame are formed. Thin film actuator substrate.   The shape memory alloy thin film actuator substrate according to claim 11, wherein the intermediate layer is an oxide of a substrate material.   The shape memory alloy thin film is composed of Ti-Ni-Cu containing 50 atomic% or more and 55 atomic% or less of Ti, 10 atomic% or more and 20 atoms or less of Cu, the balance being Ni and inevitable impurities. The shape memory alloy thin film actuator substrate according to claim 1, wherein the shape memory alloy thin film actuator substrate is an alloy thin film.   The shape memory alloy thin film has a compositional element of Ti of 45 atomic percent or more and less than 50 atomic percent, atomic percent exceeding 10 + 1.6 × (50-Ti atomic percent), and 20 + 1.6 × (50-Ti The shape memory alloy thin film actuator substrate according to any one of claims 1 to 12, wherein the thin film is a Ti-Ni-Cu alloy thin film containing at most Cu and at least Ni and inevitable impurities. .   The shape memory alloy thin film is composed of Ti—Ni—Cu containing 50 atomic% or more and 55 atomic% or less of Ti, 5 atomic% or more and 10 atomic% or less of Cu, and the balance being Ni and inevitable impurities. The shape memory alloy thin film actuator substrate according to claim 1, wherein the shape memory alloy thin film actuator substrate is an alloy thin film.   The shape memory alloy thin film actuator substrate according to any one of claims 1 to 15, wherein the moving object is a lens or an image sensor, or a part incorporating the lens or the image sensor.   The shape memory alloy thin film actuator substrate according to claim 16, wherein the moving object is a lens or a part incorporating the lens, and the movable portion has an opening window for securing an optical path.   The bias that is displaced perpendicularly to the surface of the fixed frame on the movable part of the shape memory alloy thin film actuator substrate according to any one of claims 1 to 17 or the moving object held by the movable part. A drive mechanism in which a spring is contacted or joined directly or via a spacer, and the movable portion is displaced perpendicularly to the surface of the fixed frame.   The bias spring is installed on the opposite side of the surface on which the shape memory alloy thin film is formed with respect to the movable portion, and the movable portion is pressed from the opposite side of the surface on which the shape memory alloy thin film is formed. The drive mechanism according to claim 18.   The drive mechanism according to claim 18 or 19, wherein the bias spring is the shape memory alloy thin film actuator substrate according to any one of claims 1 to 15.   The drive current from the autofocus control circuit is energized to the shape memory alloy thin film of the drive mechanism according to any one of claims 18 to 20, thereby controlling the electric resistance of the shape memory alloy thin film to perform autofocus. A camera module configured to provide the functions to perform.   The wiring including the shape memory alloy thin film on the shape memory alloy thin film actuator substrate built in the camera module according to claim 21 is energized from one end of the fixed frame to the other end of the fixed frame via the movable portion. A camera module characterized in that the camera module is configured to.   The drive current from the camera shake correction control circuit is energized independently to each of the shape memory alloy thin film of the shape memory alloy thin film actuator substrate of the drive mechanism according to any one of claims 18 to 20, A camera module characterized by tilting a movable part. A camera-equipped mobile phone or a small camera, wherein the camera module according to any one of claims 21 to 23 is mounted.