Actuator and movable mirror

Abstract

The present invention employs an actuator including: a movable portion connected to a reflecting member having a reflective surface; a movable comb electrode disposed at a distance from the reflecting member, supported by the movable portion, and extended in a direction parallel to the reflective surface; a stationary comb electrode supported by a supporting portion, extends in the direction parallel to the reflective surface, and disposed alternately with the movable comb electrode; and a voltage controller that applies a voltage to the movable comb electrode and the stationary comb electrode to displace the movable comb electrode and the movable portion in a direction normal to the reflective surface. A portion that supports the movable comb electrode and a portion that supports the stationary comb electrode are disposed such that the movable comb electrode and the stationary comb electrode pass each other.

1 . A movable mirror comprising:
 a reflecting member having a reflective surface and an actuator,   wherein the actuator includes:   a movable portion,   a post that connects the reflecting member and the movable portion,   a movable comb electrode that is disposed at a distance from the reflecting member, is supported by the movable portion, and extends from the movable portion,   a supporting portion,   a stationary comb electrode that is supported by the supporting portion, extends from the supporting portion, and is disposed alternately with the movable comb electrode,   a voltage controller that applies a voltage to the movable comb electrode and the stationary comb electrode to displace the movable comb electrode and the movable portion in a direction normal to the reflective surface, and   a spring that suppresses the movable comb electrode and the movable portion from being displaced in a direction other than the direction normal to the reflective surface,   wherein a portion of the movable portion that supports the movable comb electrode and a portion of the supporting portion that supports the stationary comb electrode are disposed such that the movable comb electrode and the stationary comb electrode pass each other when the movable comb electrode and the movable portion are displaced in the direction normal to the reflective surface.   
     
     
         2 . The movable mirror according to  claim 1 ,
 wherein the movable comb electrode is supported by the movable portion in a cantilevered manner,   wherein the stationary comb electrode is supported by the supporting portion in a cantilevered manner, and   wherein the portion of the movable portion that supports the movable comb electrode and the portion of the supporting portion that supports the stationary comb electrode are disposed to face each other, such that the movable comb electrode and the stationary comb electrode are disposed to alternately engage with each other.   
     
     
         3 . The movable mirror according to  claim 1 , wherein the voltage controller applies different voltages to the movable comb electrode and the stationary comb electrode. 
     
     
         4 . The movable mirror according to  claim 3 , wherein the movable comb electrode and the stationary comb electrode are disposed to have portions that do not overlap each other in the direction normal to the reflective surface when the voltage controller does not apply a voltage. 
     
     
         5 . The movable mirror according to  claim 1 ,
 wherein the movable comb electrode and the stationary comb electrode have portions that do not overlap each other and portions that overlap each other in the direction normal to the reflective surface when the voltage controller does not apply a voltage,   wherein the portions that do not overlap each other of the movable comb electrode protrudes in a first sense of the direction normal to the reflective surface with respect to the portions that overlaps each other, and the portions that do not overlap each other of the stationary comb electrode protrudes in an inverse sense to the first sense of the direction normal to the reflective surface with respect to the portions that overlaps each other, and   wherein the movable comb electrode and the stationary comb electrode displace such that the portions that overlap each other increase when the voltage controller applies the voltage.   
     
     
         6 . The movable mirror according to  claim 1 , wherein the movable comb electrode and the stationary comb electrode include a plurality of electrodes that is electrically isolated in a direction normal to the reflective surface. 
     
     
         7 . The movable mirror according to  claim 6 , wherein the movable comb electrode and the stationary comb electrode are disposed to overlap each other in a direction normal to the reflective surface when the voltage controller does not apply a voltage. 
     
     
         8 . The movable mirror according to  claim 1 , wherein the spring suppresses the movable comb electrode and the movable portion from being displaced in a direction other than the direction normal to the reflective surface, by being fixed on a second supporting portion which is electrically isolated from the supporting portion and by connecting the movable portion and the second supporting portion. 
     
     
         9 . The movable mirror according to  claim 1 , wherein the spring expands in a direction horizontal to the reflective surface. 
     
     
         10 . The movable mirror according to  claim 8 , wherein suppression of displacement by the spring is feedback-controlled based on electrostatic capacitance values of the movable comb electrode and the stationary comb electrode. 
     
     
         11 . The movable mirror according to  claim 1 , further comprising:
 a plurality of the actuators,   wherein at least one of the plurality of actuators is the actuator.   
     
     
         12 . The movable mirror according to  claim 11 , wherein the reflecting member continuously covers the plurality of actuators. 
     
     
         13 . The movable mirror according to  claim 11 ,
 wherein the reflecting member is divided in a plurality of reflecting members, and   wherein the plurality of reflective members individually covers the plurality of actuators respectively.   
     
     
         14 . The movable mirror according to  claim 1 , wherein a thickness of the spring in the direction normal to the reflective surface is smaller than a thickness of the movable portion in the direction normal to the reflective surface. 
     
     
         15 . The movable mirror according to  claim 1 , wherein a length of the movable comb electrode and a length of the stationary comb electrode are substantially equal. 
     
     
         16 . A movable mirror comprising:
 a reflecting member having a reflective surface and an actuator,   wherein the actuator includes:   a movable portion,   a post that connects the reflecting member and the movable portion,   a movable comb electrode that is disposed at a distance from the reflecting member, is supported by the movable portion, and extends from the movable portion,   a supporting portion,   a stationary comb electrode that is supported by the supporting portion, extends from the supporting portion, and is disposed alternately with the movable comb electrode,   a voltage controller that applies a voltage to the movable comb electrode and the stationary comb electrode to displace the movable comb electrode and the movable portion in a direction normal to the reflective surface, and   a spring that suppresses the movable comb electrode and the movable portion from being displaced in a direction other than the direction normal to the reflective surface,   wherein the movable comb electrode and the stationary comb electrode are disposed such that the movable comb electrode and the stationary comb electrode pass each other when the movable comb electrode and the movable portion are displaced in the direction normal to the reflective surface.