JP4568234B2 - Actuator and imaging device - Google Patents

Description

  The present invention relates to an actuator that expands and contracts in a driving direction and an imaging device using the actuator.

In recent years, it has been studied to incorporate a small imaging device into a mobile device such as a mobile phone. In addition, in an imaging apparatus used for inspection in a narrow tube, it is an urgent task to reduce the size of a driving portion as well as a lens. In the image pickup of a proximity point, it is necessary to adjust the focus and finally form an image on the sensor, and the focus is adjusted by driving the lens. A voice coil actuator may be used as a drive source for driving the lens in the optical axis direction (see, for example, Patent Document 1). An imaging apparatus using a voice coil actuator includes, for example, a lens, a lens housing, an elastically deformable lens support spring, a magnetic circuit composed of a magnetic material, a permanent magnet serving as a magnetomotive force, and a drive coil for passing a drive current. The mover holds the lens.
JP-A-11-289743

  In an imaging device using a voice coil actuator, a magnetic circuit is formed of a magnetic material, a gap is provided in the middle of the magnetic circuit, a drive coil joined to a lens housing is disposed therein, and Lorentz force is used. The lens must be driven. Therefore, a space for arranging the magnetic circuit, a space for securing the number of turns of the drive coil disposed on the lens, and the like are necessary. In particular, it is difficult to dispose the actuator when the diameter is 10 mm or less.

  Therefore, an object of the present invention is to provide an actuator that can be easily miniaturized and an imaging device including the actuator.

  In order to solve the above-described object, the present invention provides a first, second, and third actuator that extend and contract in the driving direction, each extending in a direction crossing the driving direction and sequentially arranged adjacent to each other in the driving direction. The arm member, the first arm member, and the second arm member are supported so as to be able to rotate or rotate relative to each other around a rotation axis extending in a direction in which each arm member extends and in a direction crossing the driving direction. The first support member, the second arm member, and the third arm member can rotate or rotate relative to each other around a rotation axis that extends in the direction in which each arm member extends and in the direction across the driving direction. A second support member that supports the first arm member, the first arm member connected between the first arm member and the second arm member, and expandable and contractable by an external signal, the second arm member and the first arm member 3 arm members And a second elastic member that can be expanded and contracted by an external signal, wherein the first support member is disposed between the first and second elastic members in the extending direction of the second arm member. It is arranged on the first elastic member side, and the second support member is on the second elastic member side between the first support member and the second elastic member in the extending direction of the second arm member. It is characterized by being arranged.

  According to the present invention, in the imaging device whose focal position changes in the driving direction, each of the first, second, and third elements extends in a direction crossing the driving direction and is sequentially arranged adjacent to each other in the driving direction. The arm member, the first arm member, and the second arm member are supported so as to be able to rotate or rotate with respect to each other around a rotation axis extending in a direction in which each arm member extends and in a direction crossing the driving direction. The first support member, the second arm member, and the third arm member can rotate or rotate with respect to each other around a rotation axis that extends in the direction in which each arm member extends and in the direction across the driving direction. A second support member that supports the first arm member, a first arm member that is connected between the first arm member and the second arm member, and that can be expanded and contracted by an external signal, the second arm member, and a third arm member. Connected between the arm members of A second telescopic member that can be expanded and contracted by a partial signal, a lens attached to the third arm member, and an imaging device disposed at a predetermined distance from the lens in the driving direction. The first support member is disposed on the first elastic member side between the first and second elastic members in the extending direction of the second arm member, and the second support member is the first elastic member. The second arm member is disposed on the second elastic member side between the first support member and the second elastic member in the extending direction of the second arm member.

  According to the present invention, it is possible to obtain an actuator that can be easily miniaturized and an imaging apparatus including the actuator.

  Embodiments of an actuator and an imaging apparatus according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted. In the description of the embodiments, the vertical and horizontal directions indicate relative directions when it is assumed that the Z axis + direction is up and the X axis + direction is the front with respect to the actuator and the image sensor.

[Embodiment 1]
1 is a diagram illustrating an actuator according to a first embodiment of the present invention, and is a cross-sectional view taken along the line I-I in FIG. 2. FIG. 2 is a diagram illustrating the actuator according to the first embodiment of the present invention, and is a front view taken along the line II-II in FIG. 1.

  The actuator 7 of this embodiment expands and contracts with the X direction as the driving direction.

  The actuator 7 includes an arm member guide 31, arm members 23, 23 a, 23 b and a controller 40. There are three types of arm members 23, 23a, and 23b: an intermediate arm member 23, a fixed arm 23a, and a tip arm 23b.

  The arm member guide 31 has a guide base portion 36, a guide upper portion 33, a guide side portion 34, and a guide bottom portion 35. Two elongated plate-like guide bottom portions 35 extending in parallel with the driving direction (X direction) are attached to the prism-shaped guide base portion 36. Two guide side portions 34 extending from the guide base portion 36 in the same direction (X direction) as the guide bottom portion 35 are attached on the guide bottom portion 35. On the guide base part 35 and the guide side part 34, the flat guide upper part 33 is attached so that the whole may be covered.

  Inside the arm member guide 31, a fixed arm 23a, an intermediate arm member 23, and a tip arm 23b are incorporated. A short prismatic fixing arm 23 a is fixed to the guide base 36. A prismatic intermediate arm member 23 is attached to the fixed arm 23 a via a support member 24 so as to straddle the two guide bottom portions 35. Another intermediate arm member 23 is also attached to the intermediate arm member 23 via a support member 24. In this way, the plurality of intermediate arm members 23 are connected to each other via the support member 24. A distal arm 23 b is attached to the intermediate arm member 23 that is located farthest from the guide base 36.

  The support member 24 can rotate (or rotate) around a rotation axis extending in a direction (Z direction) that intersects a direction (Y direction) in which the intermediate arm member 23 extends and a direction (X direction) in which the guide side portion 34 extends (Z direction). In addition, the intermediate arm member 23 is supported. That is, the intermediate arm member 23 and the distal arm 23b can rotate (or rotate) about the vertical direction (Z direction) in FIG. Further, the support member 24 has elasticity, and when the relative position of two arm members connected to each other via the support member 24 changes, a force to return the relative position to a predetermined position is generated. appear.

  In the present embodiment, the arm members 23, 23a, and 23b extend in the Y direction. However, the arm members 23, 23a, and 23b do not necessarily have to extend in the Y direction as long as they cross the drive direction (X direction). The support member 24 supports the arm members 23, 23a, and 23b so that the arm members 23, 23a, and 23b can be rotated (or rotated) about the Z direction, but crosses the arm members 23, 23a, and 23b and the driving direction (X direction). If it is a direction, the rotation axis is not necessarily the Z axis.

  FIGS. 3A and 3B are views showing one intermediate arm member and its vicinity according to the first embodiment of the present invention, wherein FIG. 3A is a top view taken along the line A-A in FIG. 3B, and FIG. BB arrow front view, (c) is a CC arrow bottom view of (b).

  The support member 24 is attached to both sides of the intermediate arm member 23 in the direction (X direction) in which the guide side portion 34 extends. Further, the support member 24 is attached to both sides of the intermediate arm member 23 in the longitudinal direction center and in the vicinity of the end of the intermediate arm member 23. The telescopic member 26 is attached to the other intermediate arm member 23, the fixed arm 23a, or the distal arm 23b between the support member 24 and the end of the intermediate arm member 23. That is, the support member 24 is provided on the side of the telescopic member 26 of the intermediate arm member 23. In the support member 24 and the elastic member 26, the distance (L1) between the support member 24 and the elastic member 26 attached in the vicinity of one end of the intermediate arm member 23 is the distance (L2) between the two support members 24. ) Is arranged so as to be smaller than.

  The elastic member 26 is expanded and contracted by an electrical signal, and for example, a shape memory alloy can be used. On the upper surface of the intermediate arm member 23, a conductor 25 extends in the longitudinal direction so as to be connected to the elastic member 26 in order to transmit an electric signal to the elastic member 26.

  The elastic member 26 connected to the distal arm 23b is connected to a return conductor 25b located on the lower surface of the distal arm 23b. Further, the controller 40 is communicated with a return conductor 25 b attached to the lower surface of each intermediate arm member 23. Between the intermediate arm members 23, the return conductors 25 b are connected to each other on the lower surface of the other intermediate arm member 23 below the support member 24. Thus, since the return conductor 25b is attached in the vicinity of the support member 24 where the change in the distance due to the expansion and contraction of the expansion / contraction member 26 is small, the change in the length of the return conductor 25b is small, and there is a risk of disconnection due to repeated expansion and contraction. small.

  The actuator controller 40 is connected to the conductor 25 and the return conductor 25b communicated from the main body of the actuator. The controller 40 is provided with a switch 41 and a power source 42 inserted between the conductor 25 and the return conductor 25b. By connecting the switch 41, a current flows from the power source 42 to the expandable member 26 through the conductor 25 and the return conductor 25b.

  Instead of the return conductor 25b, a conductor (not shown) is attached to the guide bottom 35, and a conductor (not shown) connecting the expansion member 26 on the upper surface of the distal arm 23b and the lower surface of the distal arm 23b. It may be connected to the controller 40 via. Alternatively, a flexible wire (not shown) may be connected to the elastic member 26 connected to the distal arm 23b, and the controller 40 may be connected via the flexible wire.

  In the present embodiment, the plurality of elastic members 26 are electrically connected to the controller 40 in series, but each elastic member 26 is independently connected to a signal transmission means (not shown) such as a flexible wire. The signal transmission means may be used to connect to the controller 40. In this case, it is not necessary to attach the conductor 25 and the return conductor 25b to the intermediate arm member 23. Further, by connecting each of the expansion / contraction members 26 to a plurality of independent controllers 40, the expansion / contraction members 26 can be expanded / contracted independently, and the intermediate arm member 23 can be moved independently. Become.

  Next, the operation of this actuator will be described.

  FIG. 4 is a cross-sectional view taken along the arrow I-I in FIG. 2 showing a state where the actuator according to the first embodiment of the present invention is extended.

  The elastic member 26 expands and contracts when an electric signal is transmitted. For example, when a material that contracts by an electric signal is used as the expansion / contraction member 26, the expansion / contraction member 26 contracts when the switch 41 is connected, and the expansion / contraction member 26 extends when the switch 41 is disconnected.

  When the expansion / contraction member 26 contracts, the other support member 24 attached to the intermediate arm member 23 also moves with the vicinity of the attachment position of the support member 24 as a fulcrum. This moving distance is approximately the ratio (L2 / L1) of the distance (L1) from the support member 24 to the telescopic member 26 to the distance (L2) from the support member 24 to the attachment position of the support member 24 to the intermediate arm member 23. , Multiplied by the length reduction amount of the elastic member 26. The intermediate arm member 23 is sequentially connected via the support member 24, and the mounting position of the support member 24 is moved by the expansion / contraction of the expansion / contraction member 26. Therefore, the movable body mounting portion 8 on the distal arm 23b also moves.

  In the present embodiment, the distance (L1) from the attachment position of the support member 24 that is the fulcrum (or the vicinity of the fulcrum) to the attachment position of the expansion and contraction member 24 that is the power point is the other point that is the action point from the attachment position of the support member 24 Shorter than the distance (L2) to the mounting position of the support member 24. For this reason, the amount of displacement of the action point is larger than the amount of displacement of the force point, and the amount of displacement of the movable member mounting portion 8 can be made larger than the change of the length of the telescopic member 26. Moreover, since the some expansion-contraction member 26 is used, the displacement amount of the movable member attaching part 8 can be enlarged. The number of intermediate arm members 23 may be increased or decreased as appropriate according to the required moving distance.

  As the elastic member 26, a shape memory alloy can be used. In the shape memory alloy, the current shrinks due to the flow and the temperature rise, and when the current is stopped, the temperature of the expansion / contraction member is lowered by the surrounding air, and the movable member attaching portion 8 can be moved. Since some shape memory alloys shrink about 5%, it is possible to secure a sufficient movement distance. Further, when a thin wire-shaped shape memory alloy of about 0.1 to 0.2 mm is used, for example, heat dissipation is fast when current is stopped, and sufficient responsiveness can be ensured. Furthermore, there is a shape memory alloy in which the amount of current and the amount of expansion / contraction have a linear relationship.

  As the elastic member 26, a piezoelectric element can be laminated and used. Further, when an expansion member 26 is used that expands when an electric signal is passed, it may be assembled so that the actuator is extended when no electric signal is flowing, that is, as shown in FIG.

  Since the expansion / contraction member 26 expands / contracts by an electric signal, the expansion / contraction amount of each expansion / contraction member 26, that is, the movement amount of the movable body attaching portion 8 can be controlled by the current supplied from the controller 40. When a shape memory alloy is used for the expansion / contraction member 26, the amount of expansion / contraction is determined by the temperature of the expansion / contraction member 26. Therefore, the amount of current flowing through the expansion / contraction member 26 is changed, or the time during which current flows through the expansion / contraction member 26 is changed. Therefore, the amount of expansion and contraction can be controlled.

  Further, the support member 24 has elasticity, and when the elastic member 26 loses the contracting force, the intermediate arm member 23 is returned to a predetermined position. That is, when the switch 41 is connected and the expansion / contraction member 26 is contracted, and the switch 41 is disconnected after the state shown in FIG. 4 is reached, no current flows through the expansion / contraction member 26 and the expansion / contraction member 26 contracts. And return to the state shown in FIG.

  As the support member 24, engineering plastics such as polybutyl terephthalate (PBT) and polycarbonate (PC) can be used, for example.

  In place of the elastic support member 24 as in this embodiment, a non-elastic support member (not shown) and an elastic body (not shown) may be used in combination. In other words, the support member simply supports the arm members 23, 23 a, and 23 b so that the arm members 23, 23 a, and 23 b can rotate (or rotate), and the elastic body moves relative to the arm members 23, 23 a, and 23 b by the expansion and contraction of the expansion and contraction member 26. Is changed, a force is generated to return the arm members 23, 23a, 23b to a predetermined position. In this case, for example, a hinge is used as a support member to support the arm member at the same position as in the present embodiment, and an elastic body such as a spring is interposed between the arm members at a position opposite to the expansion / contraction member 26 across the support member. By connecting the two, the same operation as in the present embodiment can be performed.

  As described above, the actuator according to the present embodiment can be easily downsized because there are no disadvantageous parts such as a magnetic circuit.

[Embodiment 2]
FIG. 5 is a diagram illustrating the imaging apparatus according to the second embodiment of the present invention, and is a cross-sectional view taken along line VV in FIG. 6. 6 is a diagram illustrating the imaging apparatus according to the second embodiment of the present invention, and is a cross-sectional view taken along the line VI-VI in FIG. 5. FIG. 7 is a diagram illustrating the imaging apparatus according to the second embodiment of the present invention, and is a vertical sectional view taken along arrows VII-VII in FIGS.

  The imaging device 60 of this embodiment includes a housing 4, an actuator 7, and an imaging mechanism. The actuator 7 is the same as the actuator of the first embodiment. Other than the controller 40 of the actuator 7 is housed in the housing 4. The housing 4 has a cylindrical shape, and one bottom surface thereof forms an opening (housing opening portion 5), and the other bottom surface (housing bottom portion 6) is closed.

  The imaging mechanism includes a lens 1, an imaging element 2, and a signal processing device 3.

  A columnar lens holder attachment member 32 is attached to the movable member attachment portion 8 of the actuator 7, and the lens holder 21 is attached to the lens holder attachment member 32. The lens 1 is held on the lens holder 21. The signal processing device 3 is fixed to the housing bottom 6, and the image sensor 2 is fixed to the signal processing device 3. A signal is transmitted from the image sensor 2 to the signal processing device 3 from the image sensor 2 by signal transmission means (not shown).

  In the signal processing device 3, two guide pins 51 extend in the direction of the housing opening 5 in parallel to the cylindrical axis of the housing 4 (X direction). Two guide pin through plates 50 are attached to the lens holder 21, and the guide pins 51 are assembled so as to pass through a hole penetrating the central portion of the guide pin through plate 50. The lens holder attachment member 32 can rotate around its columnar axis with respect to the distal arm 23 b, and the optical axis of the lens 1 is always parallel to the cylindrical axis of the housing 4 (X direction). It is like that. Further, the optical axis of the lens 1 is arranged so as to be positioned at the center of the imaging device 60.

  Next, the operation of the imaging device 60 will be described.

  The lens 1 can be moved in the optical axis direction (X direction) by an actuator 7.

  The subject image can be formed on the image sensor 2 by changing the distance from the image sensor 2 fixed to the housing 4. That is, the focus can be adjusted. The signal processor 3 may have an automatic focus adjustment function to automatically adjust the focus. In this case, a signal is transmitted from the signal processor 3 to the controller 40 to control the actuator 7.

  Note that the housing 4 may not have a cylindrical shape but may have another shape such as a rectangular parallelepiped. Further, a lid (not shown) made of a material that transmits light, such as glass, may be fitted into the housing opening 5.

  As described above, by using a small actuator, it is possible to obtain a small imaging device capable of focus adjustment.

[Embodiment 3]
FIG. 8 is a front view of the imaging apparatus according to the third embodiment of the present invention. FIG. 9 is a view showing one intermediate arm member and its vicinity according to the third embodiment of the present invention, in which (a) is a top view taken along line AA of (b), and (b) is (a). BB arrow side view, (c) is a CC arrow bottom view of (b).

  The actuator 7 according to the present embodiment has a substantially semi-cylindrical shape, and is arranged so as to surround the lens 1 and the image pickup device 2 in a coaxial manner within a cylindrical housing 4.

  The intermediate arm member 23 of the actuator 7 has a shape in which a prismatic arm end portion 23d is coupled to both ends of a semicircular arc arm central portion 23c. The two arm end portions 23d are located in substantially the same plane. The support member 24 and the expansion / contraction member 26 are attached to the arm end portion 23d, and the attachment position of the support member 24 and the attachment position of the expansion / contraction member 26 serving as a power point are located in substantially the same plane. The distal arm 23b has the same shape as the intermediate arm member 23. In the support member 24 and the elastic member 26, the distance (L1) between the support member 24 and the elastic member 26 attached in the vicinity of one end of the intermediate arm member 23 is the distance (L2) between the two support members 24. ) Is arranged so as to be smaller than.

  As the arm member guide, a combination of a semicircular guide upper portion 33 matched with the shape of the arm member 23 and the tip arm 23b and an elongated plate-like guide bottom portion 35 is used.

  By using such an actuator 7, the intermediate arm member 23 does not rotate around a straight line connecting the mounting positions of the support member 24 due to the expansion and contraction of the expansion and contraction member 26, and the movable body mounting portion 8 can transmit the light of the lens 1. Move linearly in the axial direction.

  When the expansion / contraction member 26 contracts, the other support member 24 attached to the intermediate arm member 23 also moves with the vicinity of the attachment position of the support member 24 as a fulcrum. This movement distance is approximately the distance (L2) from the support member 24 to the attachment position of the support member 24 to the intermediate arm member 23, as in the case of using the linearly extending intermediate arm member as in the first embodiment. The ratio (L2 / L1) of the distance (L1) from the support member 24 to the stretchable member 26 with respect to the product is multiplied by the length reduction amount of the stretchable member 26.

  Thus, by making the intermediate arm member 23 and the tip arm 23b into a semicircular arc shape, useless space is reduced inside the cylindrical housing 4, and the entire imaging device 60 can be downsized.

  The actuator 7 is arranged in a substantially cylindrical shape as a whole by arranging the adjacent semicircular arc-shaped intermediate arm members 23 at positions where they are inverted by 180 ° across the XY plane, instead of being semicylindrical as a whole. You can also

  Moreover, even if the shape of the arm member is a shape other than a linear shape or a semicircular arc shape, an actuator 7 that performs the same operation is obtained by arranging the support member 24 and the elastic member 26 in substantially the same plane. be able to. Therefore, the shape of the arm member can be appropriately changed in accordance with the shape of the housing 4 that houses the actuator 7.

[Embodiment 4]
FIG. 10 is a longitudinal sectional view of an imaging apparatus according to Embodiment 4 of the present invention.

  The imaging apparatus according to the present embodiment incorporates two actuators 7 so that the two lenses 1 can move independently.

  Inside the housing 4, the two lenses 1 held by the lens holder 21 are arranged so that the optical axes are the same. It is assembled so that the center of the image sensor 2 is positioned on this optical axis. The two sets of actuators having the movable arm 23, the support 24, the telescopic member 26, and the like can move each lens 1 independently.

  Since the two lenses 1 can be moved independently, the imaging apparatus also has a zoom function. The actuator controller (not shown) may be a combination of two power sources and switches, but may be one that automatically performs focusing, for example.

  In this embodiment, two actuators are incorporated. However, if the electric signals to each of the telescopic members 26 can be controlled independently, the two lenses 1 can be moved independently by one actuator. It is.

[Embodiment 5]
FIG. 11 is a partially cutaway perspective view of the in-pipe inspection system according to the fifth embodiment of the present invention.

  The in-pipe inspection system is provided with an imaging device 60, a monitor 62, and a cable 63 that connects the imaging device 60 and the monitor 62. As the imaging device 60, any of the imaging devices according to the second to fourth embodiments can be used.

  The imaging apparatus 60 moves the lens using the above-described actuator to focus, and images with the imaging element inside the imaging apparatus 60. The captured image is transmitted to the monitor 62 via the cable 63 and displayed. The monitor 62 also serves as a controller, and controls the actuator in the imaging device 60. The actuator control signal is transmitted via the cable 61. Since such an in-pipe inspection system uses a small actuator, even a pipe with a small imaging device and a small inner diameter can be inspected with a focused image. In addition, a minute portion can be observed by the zoom function. Furthermore, the side surface of the pipe can be observed in detail by combination with a mirror.

  In addition, this invention is not limited to each above-mentioned embodiment, It is not limited to the upper and lower sides, right and left of a figure, It can implement with various forms. Further, the object to be moved is not limited to the lens, but can be applied to an arm of a robot working in a minute region.

It is a figure which shows the actuator of Embodiment 1 which concerns on this invention, Comprising: It is the II arrow directional cross-sectional view of FIG. It is a figure which shows the actuator of Embodiment 1 which concerns on this invention, Comprising: It is the II-II arrow front view of FIG. It is a figure which shows one intermediate arm member of Embodiment 1 which concerns on this invention, and its vicinity, Comprising: (a) is the AA arrow top view of (b), (b) is BB of (a). An arrow front view and (c) are CC arrow bottom views of (b). FIG. 3 is a plan cross-sectional view taken along the line I-I in FIG. It is a figure which shows the imaging device of Embodiment 2 which concerns on this invention, Comprising: It is the VV arrow flat sectional view of FIG. It is a figure which shows the imaging device of Embodiment 2 which concerns on this invention, Comprising: It is VI-VI arrow sectional drawing of FIG. It is a figure which shows the imaging device of Embodiment 2 which concerns on this invention, Comprising: It is a VII-VII arrow longitudinal cross-sectional view of FIG. 5 and FIG. It is a front view of the imaging device of Embodiment 3 concerning the present invention. It is a figure which shows one intermediate arm member of Embodiment 3 which concerns on this invention, and its vicinity, Comprising: (a) is an AA arrow top view, (b) is BB of (a). An arrow side view and (c) are CC arrow bottom views of (b). It is a longitudinal cross-sectional view of the imaging device of Embodiment 4 which concerns on this invention. It is a partially notched perspective view of the in-pipe inspection system of Embodiment 5 which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lens, 2 ... Image pick-up element, 3 ... Signal processing apparatus, 4 ... Housing | casing, 5 ... Housing | casing opening part, 6 ... Housing | casing bottom part, 7 ... Actuator, 8 ... Movable body attaching part, 21 ... Lens holding body, 23 ... Intermediate arm member, 23a ... Fixed arm, 23b ... Tip arm, 23c ... Arm center, 23d ... Arm end, 24 ... Support member, 25 ... Conductor, 25b ... Return conductor, 26 ... Telescopic member, 31 ... Arm member guide, 32 ... Lens holder attaching member, 33 ... Guide top, 34 ... Guide side, 35 ... Guide bottom, 36 ... Guide base, 40 ... Controller, 41 ... Switch, 42 ... Power supply, 50 ... Guide pin Through plate, 51 ... guide pin, 60 ... imaging device, 61 ... cable, 62 ... monitor, 63 ... piping

Claims (12)

In an actuator that expands and contracts in the drive direction,
First, second and third arm members each extending in a direction transverse to the drive direction and arranged in sequence adjacent to each other in the drive direction;
A first support that supports the first arm member and the second arm member so that the first arm member and the second arm member can rotate or rotate relative to each other around a rotation axis extending in a direction in which each arm member extends and in a direction crossing the driving direction. Members,
A second support that supports the second arm member and the third arm member so that the second arm member and the third arm member can rotate or rotate with respect to each other around a rotation axis extending in a direction in which each arm member extends and in a direction crossing the driving direction. Members,
A first elastic member connected between the first arm member and the second arm member, and capable of expanding and contracting by an external signal;
A second telescopic member connected between the second arm member and the third arm member, and expandable and contractable by an external signal;
Have
The first support member is arranged on the first elastic member side between the first and second elastic members in the extending direction of the second arm member, and the second support member is the second elastic member. Arranged on the second elastic member side between the first support member and the second elastic member in the direction in which the arm member extends,
An actuator characterized by.   The distance between the first elastic member and the first supporting member is smaller than the distance between the first elastic member and the second supporting member, and the second elastic member and the first supporting member are small. 2. The actuator according to claim 1, wherein a distance between the two support members is smaller than a distance between the second elastic member and the first support member.   The actuator according to claim 1, wherein the first, second, and third arm members extend in an arc shape.   4. The actuator according to claim 1, wherein the first and second support members and the first and second elastic members are arranged in the same plane. 5. When the relative positions of the first arm member and the second arm member change due to the expansion and contraction of the first elastic member, the relative positions of the first arm member and the second arm member are changed. A first elastic body attached between the first arm member and the second arm member that generates a force to return to a predetermined position;
When the relative positions of the second arm member and the third arm member change due to expansion and contraction of the second elastic member, the relative positions of the second arm member and the third arm member are changed. A second elastic body attached between the second arm member and the third arm member, which generates a force to return to a predetermined position;
The actuator according to any one of claims 1 to 4, characterized by comprising: When the relative positions of the first arm member and the second arm member change due to expansion and contraction of the first elastic member, the first support member changes the first arm member and the second arm member. Generate a force to return the relative position of the arm member to a predetermined position,
When the relative positions of the second arm member and the third arm member change due to expansion and contraction of the second elastic member, the second support member changes the second arm member and the third arm. The actuator according to any one of claims 1 to 4, wherein a force for returning a relative position of the arm member to a predetermined position is generated.   The actuator according to claim 1, wherein the elastic member is a shape memory alloy. The external signal is an electrical signal,
The actuator according to any one of claims 1 to 7, further comprising a plurality of conductors that transmit the electrical signal to the expandable member.   The actuator according to claim 8, wherein at least a part of the conductor is disposed along the second arm member.   9. The actuator according to claim 8, further comprising a controller for generating the electrical signal, wherein the first and second elastic members are electrically connected in parallel.   9. The actuator according to claim 8, further comprising a controller that generates the electrical signals independent of each other and transmitted independently to the first and second elastic members. In an imaging device whose focal position changes in the driving direction,
First, second and third arm members each extending in a direction transverse to the drive direction and arranged in sequence adjacent to each other in the drive direction;
A first support that supports the first arm member and the second arm member so that the first arm member and the second arm member can rotate or rotate relative to each other around a rotation axis extending in a direction in which each arm member extends and in a direction crossing the driving direction. Members,
A second support that supports the second arm member and the third arm member so that the second arm member and the third arm member can rotate or rotate with respect to each other around a rotation axis extending in a direction in which each arm member extends and in a direction crossing the driving direction. Members,
A first elastic member connected between the first arm member and the second arm member, and capable of expanding and contracting by an external signal;
A second telescopic member connected between the second arm member and the third arm member, and expandable and contractable by an external signal;
A lens attached to the third arm member;
An image sensor disposed at a predetermined distance from the lens in the driving direction;
Have
The first support member is arranged on the first elastic member side between the first and second elastic members in the extending direction of the second arm member, and the second support member is the second elastic member. Arranged on the second elastic member side between the first support member and the second elastic member in the direction in which the arm member extends,
An imaging apparatus characterized by the above.

Images