Optical module and distance measurement device
An optical module includes a support, a movable part supported by the support so as to be swingable about an axis, a mirror provided to the movable part, a drive coil provided to the movable part, a temperature monitoring element provided to the support, and a magnet that generates a magnetic field acting on the drive coil. The support is thermally connected to the magnet.
1. An optical module comprising:
a support;
a movable part supported by the support so as to be swingable about an axis;
a mirror provided to the movable part;
a drive coil provided to the movable part;
a temperature monitoring element provided to the support; and
a magnet that generates a magnetic field acting on the drive coil, wherein
the support is thermally connected to the magnet,
a thermal conductivity of the support is 100 or more times higher than a thermal conductivity of air,
the temperature monitoring element is a temperature monitoring resistor of which a resistance value is changed in accordance with temperature, and
the temperature monitoring resistor is configured as a coil wound a plurality of times at the support.
2. The optical module according to claim 1 ,
wherein the movable part includes a first movable part supported by the support so as to be swingable about a first axis, and a second movable part supported by the support so as to be swingable about a second axis crossing the first axis,
the mirror is provided to the first movable part,
the first movable part is connected to the second movable part so as to be swingable about the first axis, and
the second movable part is connected to the support so as to be swingable about the second axis.
3. The optical module according to claim 2 ,
wherein the drive coil includes a first drive coil provided to the first movable part.
4. The optical module according to claim 3 , further comprising:
an electromotive force monitoring coil provided to the first movable part,
wherein the magnet generates a magnetic field acting the drive coil and the electromotive force monitoring coil.
5. The optical module according to claim 2 ,
wherein the drive coil includes a second drive coil provided to the second movable part.
6. The optical module according to claim 5 , further comprising:
an electromotive force monitoring coil provided to the first movable part,
wherein the magnet generates a magnetic field acting the drive coil and the electromotive force monitoring coil.
7. The optical module according to claim 5 , further comprising:
an electromotive force monitoring coil provided to the second movable part,
wherein the magnet generates a magnetic field acting the drive coil and the electromotive force monitoring coil.
8. The optical module according to claim 1 ,
wherein the movable part includes a first movable part supported by the support so as to be swingable about a first axis, and a second movable part supported by the support,
the mirror is provided to the first movable part,
the first movable part is connected to the second movable part so as to be swingable about the first axis,
the second movable part is connected to the support so that the first movable part is swingable about the first axis by vibration of the second movable part, and
the drive coil includes a second drive coil provided to the second movable part.
9. The optical module according to claim 8 , further comprising:
an electromotive force monitoring coil provided to the first movable part,
wherein the magnet generates a magnetic field acting the drive coil and the electromotive force monitoring coil.
10. The optical module according to claim 8 , further comprising:
an electromotive force monitoring coil provided to the second movable part,
wherein the magnet generates a magnetic field acting the drive coil and the electromotive force monitoring coil.
11. The optical module according to claim 2 , further comprising:
a connecting portion that connects the first movable part to the second movable part so that the first movable part is swingable about the first axis,
wherein a width of the support is larger than a width of the connecting portion when viewed in an optical axis direction of the mirror.
12. The optical module according to claim 2 , further comprising:
a connecting portion that connects the second movable part to the support so that the second movable part is swingable about the second axis crossing the first axis,
wherein a width of the support is larger than a width of the connecting portion when viewed in an optical axis direction of the mirror.
13. The optical module according to claim 1 , further comprising:
an electrode pad provided to the support; and
a wire connected to one end of the drive coil and the electrode pad,
wherein the electrode pad is provided inside the temperature monitoring resistor when viewed in an optical axis direction of the mirror.
14. The optical module according to claim 1 ,
wherein the support is formed in a frame shape so as to surround the movable part when viewed in an optical axis direction of the mirror.
15. The optical module according to claim 1 ,
wherein the temperature monitoring element is provided to the support along an outer edge of the support when viewed in an optical axis direction of the mirror.
16. The optical module according to claim 1 ,
wherein the drive coil and the temperature monitoring element are arranged along a same plane.
17. The optical module according to claim 4 ,
wherein the drive coil, the electromotive force monitoring coil, and the temperature monitoring element are arranged along a same plane.
18. The optical module according to claim 1 ,
wherein the drive coil is embedded in the movable part.
19. The optical module according to claim 4 ,
wherein the electromotive force monitoring coil is embedded in the movable part.
20. The optical module according to claim 1 ,
wherein the temperature monitoring element is embedded in the support.
21. The optical module according to claim 1 , further comprising:
a package that accommodates the support, the movable part, the mirror, the drive coil, and the temperature monitoring element,
wherein the support is mounted on an inner surface of a base that is a part of the package, and
the magnet is mounted on an outer surface of the base so as to face the movable part.
22. The optical module according to claim 21 ,
wherein a recessed portion is formed on the inner surface of the base so as to face the movable part.
23. The optical module according to claim 21 ,
wherein the package includes a tubular side wall disposed so as to surround the support when viewed in an optical axis direction of the mirror, and
a thickness of the base in an optical axis direction of the mirror is smaller than a distance between the side wall and the support when viewed in an optical axis direction of the mirror.
24. The optical module according to claim 4 , further comprising:
a control unit that controls drive current to be applied to the drive coil based on a detection value of the temperature monitoring element and an electromotive force generated on the electromotive force monitoring coil.
25. A distance measurement device comprising:
the optical module according to claim 1 ;
a light source that emits laser light; and
a photodetector that detects the laser light through an object and the mirror.