US 12,072,602 B2
Control method of optical deflector, and optical deflection device
Takashi Sakamoto, Tokyo (JP); Yuichi Akage, Tokyo (JP); Tadayuki Imai, Tokyo (JP); Masahiro Ueno, Tokyo (JP); Sohan Kawamura, Tokyo (JP); and Soichi Oka, Tokyo (JP)
Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (JP)
Appl. No. 17/604,875
Filed by Nippon Telegraph and Telephone Corporation, Tokyo (JP)
PCT Filed Apr. 8, 2020, PCT No. PCT/JP2020/015813
§ 371(c)(1), (2) Date Oct. 19, 2021,
PCT Pub. No. WO2020/217992, PCT Pub. Date Oct. 29, 2020.
Claims priority of application No. 2019-082043 (JP), filed on Apr. 23, 2019.
Prior Publication US 2022/0221767 A1, Jul. 14, 2022
Int. Cl. G02F 1/29 (2006.01)
CPC G02F 1/29 (2013.01) 6 Claims
OG exemplary drawing
 
1. A method for controlling an optical deflector that changes a deflection angle depending on a voltage to be applied, the method for controlling the optical deflector deriving a goal voltage V=ggoal(t) for providing a deflection angle θ with goal time dependency θ=θgoal(t), wherein time is denoted by t, the method comprising:
an initial step of:
setting a period of a periodic function of time as T when θ is the periodic function of time, a period is denoted by T;
setting a duration as T and setting a start time of the deflection angle θ with the goal time dependency θ=θgoal(t) as t=0 when θ is not a periodic function of time; and
setting a number of repetitions as n=0 when time in a period 0≤t<T is considered;
an increment step of setting n=n+1;
a step An of applying a voltage gn(t) with the period T or the duration T to the optical deflector;
a step Bn of checking whether θ=θgoal(t) is satisfied with a goal accuracy next to the step An;
a step Cn of setting gn(t) as a goal voltage V=ggoal(t);
a step Dn of deriving θ=frise, n(V) indicating voltage dependency of the deflection angle θ when a voltage applied to the optical deflector rises and deriving θ=ffall, n(V) indicating the voltage dependency of the deflection angle θ when the voltage applied to the optical deflector falls;
a step En of setting grise, n+1(t)=frise, n−1 {θgoal(t)}, setting gfall, n+1(t)=ffall, n−1 (θgoal(t)), and configuring gn+1(t) from grise, n+1(t) and gfall, n+1(t), next to the step Dn; and
a step Fn of performing the increment step next to the step En,
wherein the step An is subsequent to the increment step,
in the step Bn, in a case where θ=θgoal(t) is not satisfied with the goal accuracy, the step Dn is performed following the step Bn,
in the step Bn, in a case where θ=θgoal(t) is satisfied with the goal accuracy, the step Cn is performed following the step Bn and a process is ended,
gn+1(t) is equal to grise, n+1(t) when the voltage applied to the optical deflector rises, and is equal to gfall, n+1(t) when the voltage applied to the optical deflector falls, and
the voltage dependency of the deflection angle θ when the voltage applied to the optical deflector rises is different from the voltage dependency of the deflection angle θ when the voltage applied to the optical deflector falls.