TECHNICAL FIELD

An aspect of the disclosure relates to an actuator device formed of, for example, a Micro Electro Mechanical Systems (MEMS) device.

BACKGROUND ART

An actuator device is known as a MEMS device. The actuator device includes a support part, a first movable part, a frame-shaped second movable part that surrounds the first movable part, a pair of first connecting parts that connects the first movable part to the second movable part on a first axis, and a pair of second connecting parts that connects the second movable part to the support part on a second axis orthogonal to the first axis. In such an actuator device, the first movable part is made to swing around the first axis and the second movable part is made to swing around the second axis together with the first movable part (see, for example, Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No. 2014-41234

SUMMARY OF INVENTION

Technical Problem

It is desired in the above-mentioned actuator device that the resonant frequency of the second movable part around the second axis is high to suppress the vibration of the second movable part caused by an unintended external force. On the other hand, when the first movable part swings around the first axis, the second movable part may be deformed to the side opposite to the first movable part around the first axis by a reaction against it. In this case, there is a concern that the second connecting parts need to be largely deformed to make the first movable part swing by a specified amount. Further, there is also a concern that stress may be generated at an unintended part. For this reason, it is preferable that the deformation of the second movable part around the first axis is suppressed.

An object of an aspect of the disclosure is to provide an actuator device in which a first movable part swings around a first axis and a second movable part surrounding the first movable part swings around a second axis and that can achieve both the ensuring of the resonant frequency of the second movable part around the second axis and the suppression of the deformation of the second movable part around the first axis.

Solution to Problem

An actuator device according to an aspect of the disclosure includes a support part, a first movable part, a frame-shaped second movable part that is arranged so as to surround the first movable part, a pair of first connecting parts that is arranged on both sides of the first movable part in a first axis direction parallel to a first axis and connects the first movable part to the second movable part so that the first movable part can swing around the first axis, and a pair of second connecting parts that is arranged on both sides of the second movable part in the first axis direction parallel to a second axis orthogonal to the first axis and connects the second movable part to the support part so that the second movable part can swing around the second axis. The second movable part includes a pair of first connection portions that is positioned on both sides of the first movable part on the first axis and is connected to the pair of first connecting parts, and a pair of second connection portions that is positioned on both sides of the first movable part on the second axis and is connected to the pair of second connecting parts. Each of the pair of second connection portions includes a portion having a width larger than the width of a portion of the second movable part other than the pair of first connection portions and the pair of second connection portions when viewed in a direction orthogonal to the first and second axes. An inner edge of each of the pair of second connection portions, when viewed in the direction orthogonal to the first and second axes, includes a depression portion recessed in a second axis direction, and an outer edge of each of the pair of second connection portions, when viewed in the direction orthogonal to the first and second axes, includes a protrusion portion protruding in the second axis direction.

In the actuator device, each of the pair of second connection portions positioned on both sides of the first movable part on the second axis includes a portion having a width larger than the width of a portion of the second movable part other than the pair of first connection portions and the pair of second connection portions. Accordingly, while an increase in the moment of inertia of the second movable part about the second axis is suppressed, the moment of inertia of the second movable part about the first axis can be increased. As a result, both the ensuring of the resonant frequency of the second movable part around the second axis and the suppression of the deformation of the second movable part around the first axis can be achieved. Further, the inner edge of each of the second connection portions, when viewed in the direction orthogonal to the first and second axes, includes the depression portion recessed in the second axis direction. Accordingly, the size of the second movable part can be reduced in the second axis direction, so that an increase in the moment of inertia of the second movable part about the second axis can be further suppressed. Furthermore, the outer edge of each of the second connection portions, when viewed in the direction orthogonal to the first and second axes, includes the protrusion portion protruding in the second axis direction. Accordingly, the moment of inertia of the second movable part about the first axis can be further increased. Moreover, since each of the second connection portions is positioned on the second axis, an increase in the moment of inertia of the second movable part about the second axis can be still further suppressed. Therefore, according to this actuator device, both the ensuring of the resonant frequency of the second movable part around the second axis and the suppression of the deformation of the second movable part around the first axis can be achieved in the actuator device in which the first movable part swings around the first axis and the second movable part surrounding the first movable part swings around the second axis.

In the actuator device according to the aspect of the disclosure, the second movable part may further include a pair of first linear portions that is positioned on both sides of one of the pair of second connection portions in the first axis direction and is connected to one of the pair of second connection portions, and a pair of second linear portions that is positioned on both sides of the other of the pair of second connection portions in the first axis direction and is connected to the other of the pair of second connection portions, and each of the pair of first linear portions and each of the pair of second linear portions may extend in the first axis direction. In this case, while an increase in the moment of inertia of the second movable part about the second axis is effectively suppressed, the moment of inertia of the second movable part about the first axis can be effectively increased.

In the actuator device according to the aspect of the disclosure, the second movable part may further include a pair of third linear portions that is positioned on sides opposite to one of the pair of second connection portions with respect to the pair of first linear portions and is connected to the pair of first linear portions, and a pair of fourth linear portions that is positioned on sides opposite to the other of the pair of second connection portions with respect to the pair of second linear portions and is connected to the pair of second linear portions. When viewed in a direction orthogonal to the first and second axes, one of the pair of third linear portions may extend in a direction inclined with respect to the first and second axes, the other of the pair of third linear portions may extend symmetrically to one of the pair of third linear portions with respect to the second axis, one of the pair of fourth linear portions may extend symmetrically to one of the pair of third linear portions with respect to the first axis, and the other of the pair of fourth linear portions may extend symmetrically to one of the pair of fourth linear portions with respect to the second axis. In this case, while an increase in the moment of inertia of the second movable part about the second axis is more effectively suppressed, the moment of inertia of the second movable part about the first axis can be more effectively increased.

In the actuator device according to the aspect of the disclosure, the second movable part may further include a fifth linear portion that is connected to one of the pair of first connection portions and one of the pair of second connection portions, a sixth linear portion that is connected to one of the pair of first connection portions and the other of the pair of second connection portions, a seventh linear portion that is connected to the other of the pair of first connection portions and one of the pair of second connection portions, and an eighth linear portion that is connected to the other of the pair of first connection portions and the other of the pair of second connection portions. When viewed in the direction orthogonal to the first and second axes, the fifth linear portion may extend in a direction inclined with respect to the first and second axes, the sixth linear portion may extend symmetrically to the fifth linear portion with respect to the first axis, the seventh linear portion may extend symmetrically to the fifth linear portion with respect to the second axis, and the eighth linear portion may extend symmetrically to the sixth linear portion with respect to the second axis. In this case, while an increase in the moment of inertia of the second movable part about the second axis is effectively suppressed, the moment of inertia of the second movable part about the first axis can be effectively increased.

In the actuator device according to the aspect of the disclosure, the depression portion and the protrusion portion may be positioned on the second axis when viewed in the direction orthogonal to the first and second axes. In this case, while an increase in the moment of inertia of the second movable part about the second axis is still more effectively suppressed, the moment of inertia of the second movable part about the first axis can be still more effectively increased.

The actuator device according to the aspect of the disclosure may further include a spiral coil that is provided to the second movable part so as to surround the first movable part, and a magnetic field generator that generates a magnetic field to act on the coil. In this case, both the ensuring of the resonant frequency of the second movable part around the second axis and the suppression of the deformation of the second movable part around the first axis can be achieved while an arrangement space of the coil is ensured in the second movable part.

In the actuator device according to the aspect of the disclosure, the coil may be arranged at a position that is closer to the outer edge than the inner edge of each of the pair of second connection portions on the second axis when viewed in the direction orthogonal to the first and second axes. In this case, the moment of inertia of the second movable part about the first axis can be still more effectively increased.

In the actuator device according to the aspect of the disclosure, the coil may include a portion that extends in a direction orthogonal to the magnetic field. In this case, Lorentz force, which is generated by an interaction between current flowing through the coil and a magnetic field, can be increased.

In the actuator device according to the aspect of the disclosure, the coil may be made of a metal material of which the density is higher than the density of a material of the second movable part, and may be embedded in the second movable part. In this case, the moment of inertia of the second movable part about the first axis can be still more effectively increased.

In the actuator device according to the aspect of the disclosure, each of the pair of second connection portions may include a portion having a width larger than the width of each of the pair of first connection portions. In this case, while an increase in the moment of inertia of the second movable part about the second axis is still more effectively suppressed, the moment of inertia of the second movable part about the first axis can be still more effectively increased.

In the actuator device according to the aspect of the disclosure, the depression portion may be provided over a region of each of the pair of second connection portions facing the first movable part when viewed in the direction orthogonal to the first and second axes. In this case, the moment of inertia of the second movable part about the first axis can be still more effectively increased.

In the actuator device according to the aspect of the disclosure, each of the pair of second connecting parts may extend meanderingly when viewed in the direction orthogonal to the first and second axes. In this case, the strength of each second connecting part can be improved, and the adjustment of the spring constant of each second connecting part can be facilitated. Further, an increase in the size of the device in the second axis direction can be suppressed.

Advantageous Effects of Invention

According to an aspect of the disclosure, both the ensuring of the resonant frequency of a second movable part around a second axis and the suppression of the deformation of the second movable part around a first axis can be achieved in an actuator device in which a first movable part swings around the first axis and the second movable part surrounding the first movable part swings around the second axis.

