Downsized reflecting device having oscillation part constituted by mirror pare and hinge part for making mirror part oscillate with respect to support frame for performing wide angle scanning
Provided a reflecting device in which a mirror area is large, wide angle scanning is possible, and a size thereof is reduced, and particularly a downsized reflecting device that has a suitable specification as vehicle-mounted LiDAR. The reflecting device includes an oscillation part, and the oscillation part includes a mirror part supported on a support frame, and a hinge part engaging the mirror part and the support frame. The mirror part oscillates with respect to the support frame, and the hinge part has a tensile strength of 1500 MPa or higher. A mass M of the mirror part and a resonance frequency f 0 of the oscillation part satisfy a relational expression (1) below, 0.49* f 0 +6.23≤ M ≤68.6* f 0 +46.8 (1)
1. A reflecting device, comprising:
an oscillation part, comprising:
a mirror part, supported on a support frame; and
a hinge part, engaging the mirror part and the support frame,
wherein the mirror part oscillates with respect to the support frame,
the hinge part has a tensile strength of 1500 MPa or higher,
a mass M of the mirror part and a resonance frequency f 0 of the oscillation part satisfy relational expression (1) below,
0.49 *f 0 +6.23 ≤M≤ 68.6 *f 0 +46.8 (1),
wherein the mirror part includes a metal part and a reflecting part joined with the metal part;
a reflecting layer is formed on a top surface of the reflecting part;
the reflecting part is joined and fixed to a part of the metal part, and the mirror part other than the part is thinned.
2. The reflecting device according to claim 1 , wherein
a thinning part is formed on a surface different from a reflecting surface of the mirror part; and
the mass M of the mirror part and the resonance frequency f 0 of the oscillation part satisfy relational expression (2) below,
0.49 *f 0 +6.23 ≤M≤ 43.68 *f 0 −3.12 (2).
3. The reflecting device according to claim 1 , wherein
an area S 1 of the reflecting part and an area S 2 of the metal part satisfy relational expression (3) below,
S 1≥ S 2 (3).
4. The reflecting device according to claim 1 , wherein
the metal part has a fixing part fixing an electromagnetically driving magnet to the mirror part; and
the reflecting device has a thinning part around the fixing part.
5. The reflecting device according to claim 4 , further comprising:
a coil,
wherein the coil faces the electromagnetically driving magnet.
6. The reflecting device according to claim 4 , wherein
four openings are provided as the thinning part; and
the four openings are formed to leave a magnet receiving surface for fixing the electromagnetically driving magnet to a bottom surface of the mirror part.
7. The reflecting device according to claim 4 , wherein
two openings are provided as the thinning part; and
the two openings are formed around the mirror part to be symmetrical.
8. The reflecting device according to claim 4 , wherein
upper and lower portions of the metal part constituting the mirror part are removed; and
the reflecting device has:
a meal material of which two left and right mirror parts coupled perpendicular to the hinge part are formed, and
the fixing part in a circular shape for fixing the electromagnetically driving magnet to the mirror part.
9. The reflecting device according to claim 4 , wherein
the metal part is formed of only the fixing part in a circular shape for fixing the electromagnetically driving magnet to the mirror part.
10. The reflecting device according to claim 1 , wherein
the hinge part is formed of a metal.
11. The reflecting device according to claim 1 , wherein
a piezoelectric element is mounted on the support frame.
12. The reflecting device according to claim 1 , wherein
the tensile strength of the hinge part is 3500 MPa or lower.
13. The reflecting device according to claim 1 , wherein
a dimension of a length of the hinge part which is parallel to an oscillation axis is 28 mm or less.
14. The reflecting device according to claim 1 , wherein
the oscillation part is formed to be symmetrical with respect to a center of the mirror part.
15. The reflecting device according to claim 1 , wherein
the hinge part being extended from a middle portion of left and right lateral surfaces of the mirror part, and is engaged with an inside of the support frame.
16. The reflecting device according to claim 1 , wherein
a thinning rate OP (%) calculated by forming a thinning part on a surface different from a reflecting surface of the mirror part is 20% or higher and 80% or lower.
17. The reflecting device according to claim 1 , wherein
the resonance frequency f 0 of the oscillation part is set, and
an angle generated during the oscillation part is oscillated with respect to the support frame by the resonance frequency f 0 is set to a mechanical swing angle θ Mech ; and
the mechanical swing angle θ Mech ranges from 25 degree to 35 degree.
18. The reflecting device according to claim 1 , wherein
a minimum value of the resonance frequency f 0 of the oscillation part is 1000 Hz; and
a maximum value of the resonance frequency f 0 of the oscillation part is 3000 Hz.
19. The reflecting device according to claim 1 , wherein
a surface different from a reflecting surface of the mirror part is configured to leave an outer edge of the mirror part as an outer frame, and
an inside of the mirror part is thinned to form a recess that is a thinning part.