Corrugated thermal actuator
View Patent ↗A thermal actuator for micro mechanical or micro electro-mechanical devices comprises a supporting substrate; an actuator extension portion; an anchor block extending from the substrate; a first group of at least two elongate corrugated arms attached at a first end thereof to a heating circuit at the anchor block and at a second end to the extension portion, the first group being arranged to be conductively heated through connection to the heating circuit; and a second group of at least two elongate corrugated arms attached at a first end to the anchor block and at a second end to the extension portion, the second group not being connected to a heating circuit and being spaced apart from the first group. The first edge of the at least two elongate corrugated arms of the first group and a first edge of the at least two elongate corrugated arms of the second group are in a common plane.
1. A thermal actuator for micro mechanical or micro electro-mechanical devices, the actuator comprising:
a supporting substrate having an anchor block extending therefrom, the anchor block including a heating circuit;
an actuator extension portion;
a first group of at least two elongate corrugated arms attached at a first end thereof to the heating circuit and at a second end to the extension portion, the at least two elongate corrugated arms of the first group all being in a first horizontal plane, and arranged for conductive heating via the heating circuit; and
a second group of at least two elongate corrugated arms attached at a first end to the anchor block and at a second end to the extension portion, the at least two elongate corrugated arms of the second group all being in a second horizontal plane different from the first horizontal plane, and electrically insulated from the heating circuit,
wherein a first edge of the at least two elongate corrugated arms of the first group and a first edge of the at least two elongate corrugated arms of the second group are in a common horizontal plane between the first and second horizontal planes.
2. The actuator of claim 1 , wherein the first horizontal plane is below the common horizontal plane.
3. The actuator of claim 2 , wherein a longitudinal centre of inertia of the first group is above the common horizontal plane.
4. The actuator of claim 1 , wherein the second horizontal plane is above the common horizontal plane.
5. The actuator of claim 4 , wherein the longitudinal centre of inertia of the second group is below the common horizontal plane.
6. The actuator of claim 1 , wherein the arms of said first group and said second group are spaced transversely relative to each other and, in plan view, do not overlap.
7. The actuator of claim 1 , wherein an arm of said first group and/or an arm of said second group, has, in transverse cross-section, a U, V, C or W profile.
8. The actuator of claim 1 , wherein said second group includes three elongate arms.
9. The actuator of claim 1 wherein the first group and the second group are formed as an integral unit, said first and second groups being joined at the second end to a transversely extending cross arm.