Patent Application

App. No. 12/914,833

Abstract

Claims (25)

1 . A thermo-acoustic loudspeaker comprising:

a substrate;

a heating sheet; and

a plurality of support bars supporting the heating sheet away from the substrate, the support bars at least partially defining at least one cavity between the support bars;

wherein the heating sheet extends between opposed contacts over the at least one cavity; and

wherein the heating sheet has at least one opening adjacent to each cavity;

2 . A thermo-acoustic loudspeaker according to claim 1 , wherein the support bars include porous silicon.

3 . A thermo-acoustic loudspeaker according to claim 1 wherein the support bars include silicon dioxide.

4 . A thermo-acoustic loudspeaker according to claim 1 wherein in the plane of the substrate an area ratio of support bars to a total area of support bars and cavities is not more than 25%.

5 . A thermo-acoustic loudspeaker according to claim 1 wherein the heating sheet has a resistance between 2Ω and 50Ω and a thickness of at most 10 μm.

6 . A thermo-acoustic loudspeaker according to claim 1 wherein the heating sheet includes a plurality of one of wires and sheets extending between opposed contacts over the at least one cavity.

7 . A method of manufacturing a thermo-acoustic loudspeaker, comprising:

forming a heating sheet over a first material;

patterning the heating sheet to form a pattern with openings in the heating sheet; and

removing the first material through the openings to form cavities between support structures; and

wherein the heating sheet extends between opposed contacts over the cavities.

8 . A method according to claim 7 , further comprising:

depositing a sacrificial layer as the first material on a substrate before forming the heating sheet;

9 . A method according to claim 8 wherein the sacrificial layer is photoresist, and removing the photoresist includes dissolving the photoresist in a solvent, the solvent passing through the openings in the heating sheet to dissolve the photoresist to form the cavities.

10 . A method according to claim 9 further comprising:

patterning the photoresist after deposition to define gaps, and

depositing material to form the support structures in the gaps.

11 . A method according to claim 8 , wherein the sacrificial layer includes silicon dioxide.

12 . A method according to claim 8 , wherein the sacrificial layer includes porous silicon.

13 . A method according to claim 7 wherein the first material is a substrate.

Assignments (12)