Movable reflection device and reflection surface drive system utilizing same

A movable reflective device, comprising:

• a mirror including a reflective surface;
• a support for supporting the mirror;
• an arm having one end connected to the support and another end connected to the mirror;
• and
• piezoelectric elements for causing the arm to deform in accordance with an electrical signal provided, a relative position of the mirror to the support being controllable by deformation of the arm caused by the piezoelectric elements,
• wherein the arm comprises n bridges and n+1 intermediate connectors, where n≥2, and the arm connects a predetermined portion of the support to a predetermined portion of the mirror along a single connection path,
• wherein the n bridges are plate-like structures extending along different predetermined longitudinal axes,
• wherein when one end of each bridge, closer to the support on the connection path, is referred to as a proximal end, and another end of each bridge, closer to the mirror on the connection path, is referred to as a distal end, a first intermediate connector connects the predetermined portion of the support to the proximal end of a first bridge, an ith intermediate connector connects the distal end of an (i−1)th bridge to the proximal end of an ith bridge, and an (n+1)th intermediate connector connects the distal end of an nth bridge to the predetermined portion of the mirror, where 2≤i≤n,
• wherein each of the first to (n−1)th bridges includes a proximal-end-side piezoelectric element arranged on a proximal-end side and a distal-end-side piezoelectric element arranged on a distal-end side,
• wherein each of the proximal-end-side piezoelectric element and the distal-end-side piezoelectric element is disposed on an upper surface or a lower surface of the associated bridge, and stretches and contracts a surface of the associated bridge along the longitudinal axis in accordance with the electrical signal provided, and
• wherein a pair of piezoelectric elements disposed on each of the first to (n−1)th bridges consists of a piezoelectric element having a first length and a piezoelectric element having a second length along the longitudinal axis of the bridge, the first length being longer than the second length, and when the piezoelectric element having the first length is referred to as a long element and the piezoelectric element having the second length is referred to as a short element, for an odd-numbered bridge, the proximal-end-side piezoelectric element is the short element and the distal-end-side piezoelectric element is the long element, and for an even-numbered bridge, the proximal-end-side piezoelectric element is the long element and the distal-end-side piezoelectric element is the short element.