Piezoelectric actuated scanning mirror
View Patent ↗A scanning mirror useful in laser projection devices (LPDs) is provided. The scanning mirror is comprised of a substantially planar member having a movable reflective region and a base region coupled together by a split hinge. A foundation is coupled to the base region by at least one piezoelectric element extending therebetween such that movement the piezoelectric element is transferred to the movable reflective region through the split hinge.
1. A light scanning arrangement, comprising:
a) a scan element oscillatable about an axis, and operative for reflecting light incident thereon;
b) a movable support having support portions at opposite sides of the axis;
c) a pair of torsion hinges spaced apart along the axis and connected between the movable support and the scan element for supporting the scan element for oscillation about the axis, each torsion hinge having a first hinge portion extending linearly generally parallel to the axis at one side thereof, a second hinge portion extending linearly generally parallel to the axis at an opposite side thereof, and an offset portion extending linearly across the axis and connecting the first and second hinge portions; and
d) a drive for directly moving the support portions and, in turn, for indirectly oscillating the scan element about the axis to scan the incident light.
2. The arrangement of claim 1 , wherein the scan element, the movable support and the torsion hinges are a one-piece, generally planar substrate.
3. The arrangement of claim 1 , wherein the movable support is a frame surrounding the scan element and lying in a common plane therewith in a rest position of the scan element.
4. The arrangement of claim 1 , wherein two of the support portions are provided for each torsion hinge; wherein the drive directly moves the two support portions for each torsion hinge in one circumferential direction about the axis during a part of a drive cycle, and directly moves the two support portions for each torsion hinge in an opposite circumferential direction about the axis during a remaining part of the drive cycle; and wherein the scan element is driven in a non-resonant mode in both of the circumferential directions.
5. The arrangement of claim 4 , wherein the drive includes a pair of piezoelectric devices for each torsion hinge, each piezoelectric device being connected to a respective support portion and being movable along a stroke in response to a periodic electrical drive signal.
6. The arrangement of claim 5 , wherein the movable support is a planar substrate, and wherein the piezoelectric devices lie in a plane parallel to the substrate.
7. The arrangement of claim 5 , wherein the piezoelectric devices are elongated and extend toward, but terminate short of, the axis.