Waterproof Sound Transmitting Member

1. An adhesive structure comprising a waterproof sound transmitting member and a housing, the waterproof sound transmitting member comprising: a waterproof sound transmitting membrane that allows sound to pass therethrough and prevents water from passing therethrough, the waterproof sound transmitting membrane having a first surface and a second surface opposite to the first surface; and a first adhesive sheet and a second adhesive sheet that are disposed on the first surface, wherein when viewed in a direction perpendicular to the first surface, the first adhesive sheet has a closed frame shape, and the second adhesive sheet is disposed within the frame formed by the first adhesive sheet and is spaced from the first adhesive sheet, the first adhesive sheet fixes the waterproof sound transmitting membrane and the housing together, and the second adhesive sheet fixes the waterproof sound transmitting membrane and the housing together in a region surrounded by the first adhesive sheet.

2. The adhesive structure according to claim 1 , wherein when viewed in the direction perpendicular to the first surface, an area of the second adhesive sheet is not more than one half an area of a region surrounded by an inner edge of the frame formed by the first adhesive sheet.

3. The adhesive structure according to claim 1 , wherein no adhesive sheet is disposed on the second surface.

4. The adhesive structure according to claim 1 , further comprising a third adhesive sheet disposed on the second surface, wherein no other adhesive sheet than the third adhesive sheet is disposed on the second surface, and the third adhesive sheet has the same closed frame shape as the first adhesive sheet.

5. The adhesive structure according to claim 1 , wherein the waterproof sound transmitting membrane comprises a porous polytetrafluoroethylene membrane.

6. The adhesive structure according to claim 1 , wherein the waterproof sound transmitting membrane has a maximum diameter of 7 mm to 20 mm.

7. The adhesive structure according to claim 2 , wherein when viewed in the direction perpendicular to the first surface, the area of the second adhesive sheet is at least one tenth the area of the region surrounded by the inner edge of the frame formed by the first adhesive sheet.

8. The adhesive structure according to claim 1 , wherein when viewed in the direction perpendicular to the first surface, a center of gravity of the second adhesive sheet coincides with a center of gravity of a region surrounded by an inner edge of the first adhesive sheet.

9. The adhesive structure according to claim 1 , wherein the first adhesive sheet and the second adhesive sheet have the same thickness.

10. The adhesive structure according to claim 1 , wherein a region to which the waterproof sound transmitting membrane is exposed is a frame-shaped region between an inner edge of the first adhesive sheet and an outer edge of the second adhesive sheet.

11. The adhesive structure according to claim 1 , wherein a material of the waterproof sound transmitting membrane is selected from polymer films made of polymers and porous membranes made from the polymer films.

12. A waterproof sound transmitting member comprising: a waterproof sound transmitting membrane that allows sound to pass therethrough and prevents water from passing therethrough, the waterproof sound transmitting membrane having a first surface and a second surface opposite to the first surface; and a first adhesive sheet and a second adhesive sheet that are disposed on the first surface, wherein when viewed in a direction perpendicular to the first surface, the first adhesive sheet has a closed frame shape, and the second adhesive sheet is disposed within the frame formed by the first adhesive sheet and is spaced from the first adhesive sheet, and there is no adhesive on a part of the second surface that corresponds to a location of the second adhesive sheet.

13. The waterproof sound transmitting member according to claim 12 , wherein no adhesive sheet is disposed on the second surface.

14. The waterproof sound transmitting member according to claim 12 , further comprising a third adhesive sheet disposed on the second surface, wherein no other adhesive sheet than the third adhesive sheet is disposed on the second surface, and the third adhesive sheet has the same closed frame shape as the first adhesive sheet.