US 12,248,138 B2
Light deflector and manufacturing method
Keita Akiyama, Tokyo (JP)
Assigned to STANLEY ELECTRIC CO., LTD., Tokyo (JP)
Appl. No. 17/616,605
Filed by STANLEY ELECTRIC CO., LTD., Tokyo (JP)
PCT Filed May 20, 2020, PCT No. PCT/JP2020/019976
§ 371(c)(1), (2) Date Dec. 3, 2021,
PCT Pub. No. WO2020/246245, PCT Pub. Date Dec. 10, 2020.
Claims priority of application No. 2019-106111 (JP), filed on Jun. 6, 2019.
Prior Publication US 2022/0236556 A1, Jul. 28, 2022
Int. Cl. G02B 26/08 (2006.01); G02B 26/10 (2006.01); H02N 2/00 (2006.01); H02N 2/02 (2006.01)
CPC G02B 26/0858 (2013.01) [H02N 2/028 (2013.01); H02N 2/22 (2013.01); G02B 26/105 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A light deflector comprising:
a mirror part which can turn reciprocally about a predetermined rotation axis;
a pair of torsion bars extending from both sides of the mirror part along the rotation axis of the mirror part;
a frame part which surrounds the mirror part and the pair of torsion bars;
a plurality of piezoelectric actuators intervening between the torsion bars and the frame part to cause torsional vibration of each torsion bar about the rotation axis so as to reciprocally turn the mirror part about the rotation axis;
first radius parts each of which is formed by a cylindrical curved surface recessed inward in a joint edge portion between each torsion bar and the mirror part; and
second radius parts each of which is formed by a cylindrical curved surface recessed inward in a joint edge portion between each piezoelectric actuator on a side facing the mirror part and a respective one of the torsion bars,
wherein:
a substrate layer of the mirror part, the torsion bars, and the piezoelectric actuators is a common silicon single crystal layer,
a plane index of a principal surface of the silicon single crystal layer is either one of (100) and (110),
an axial direction of the torsion bars is <100> as a crystal orientation of the silicon single crystal layer,
the first radius parts are set outside of both ends of a center divided section when the cylindrical curved surface is divided into three equal sections and are so formed that a contour line when each first radius part is cut out on a plane parallel to the principal surface is set as a waviness curve,
an average line of waviness curves is set by a method of least squares,
an adjacent peak to peak section of the waviness curve is set as a cycle,
a distance from the average line at each position of the waviness curve is set as an amount of waviness, and
a difference between a maximum amount of waviness and a minimum amount of waviness in each cycle is 600 nm or less over the whole cycle.