Bending wave panel loudspeaker

1. A method of making a bending wave panel loudspeaker, comprising:

rigidly coupling a lever to a panel marginal portion to define a region where a suspension can be attached and wherein the lever extends at an angle to the plane of the panel,

providing the lever with a return lip at its end remote from the panel,

coupling a vibration exciter to the return lip whereby bending wave energy is coupled to the panel to provide an acoustic output when the exciter is fed with a signal, and

supporting the panel on a suspension positioned outboard of the lever in said region with said suspension being adapted to provide boundary conditions which improve performance.

2. A method according to claim 1 , comprising arranging the lever to be in the form of a flange extending along a marginal portion of the panel.

3. A method according to claim 2 , comprising arranging the flange to extend part-way along the marginal portion.

4. A method according to any one of claims 1 to 3 , comprising arranging levers or flanges on a pair of opposite marginal portions of the panel, each lever or flange having a respective return lip, and coupling each return lip to a respective vibration exciter whereby the panel can be operated as a stereo device.

5. A method according to claim 4 , comprising arranging a lever or flange on an adjacent marginal portion of the panel, and coupling a vibration exciter to the lever or flange on the adjacent edge or marginal portion to provide a multiple channel acoustic output.

6. A method according to claim 1 , comprising driving the lever into resonance by the associated vibration exciter.

7. A method according to claim 6 , comprising selecting a distributed mode device as a vibration exciter.

8. A method according to any one of claims 1 to 3 , comprising positioning the exciter inboard of the lever or flange.

9. A method according to any one of claims 1 to 3 , wherein the vibration exciter applies force to the return lip generally in the plane of the panel.

10. A method according to any one of claims 1 to 3 , wherein the vibration exciter applies force to the return lip generally normally to the plane of the panel.

11. A method according to any one of claims 1 to 3 , wherein the panel is driven into resonance by the exciter.

12. A method according to claim 11 , wherein the resonance is of the distributed mode kind.

13. A bending wave panel-form loudspeaker comprising:

a panel,

a lever rigidly coupled to a marginal portion of the panel to define a region where a suspension can be attached,

a return lip on the lever at its end remote from the panel,

a vibration exciter coupled to the return lip to apply bending wave energy to the panel to produce an acoustic output, and

a panel suspension positioned outboard of the lever in said region with said suspension being adapted to provide boundary conditions which improve performance.

14. A loudspeaker according to claim 13 , wherein the lever is in the form of a flange extending along the marginal portion of the panel.

15. A loudspeaker according to claim 14 , wherein the flange extends part-way along the marginal portion.

16. A loudspeaker according to any one of claims 13 to 15 , wherein levers or flanges are provided on a pair of opposite marginal portions of the panel, each lever or flange having a respective return lip and being coupled to a respective vibration exciter whereby the loudspeaker may be operated as a stereo device.

17. A loudspeaker according to claim 16 , wherein a lever or flange is provided on an adjacent marginal portion of the panel, the lever or flange on the adjacent marginal portion being coupled to a vibration exciter to provide a multiple channel acoustic output.

18. A loudspeaker according to any one of claims 13 to 15 , wherein the lever or flange is adapted to be driven into resonance by the associated vibration exciter.

19. A loudspeaker according to claim 18 , wherein the vibration exciter is a distributed mode device.

20. A loudspeaker according to any one of claims 13 to 15 , wherein the exciter is placed inboard of the lever or flange.

21. A loudspeaker according to any one of claims 13 to 15 , wherein the vibration exciter is adapted to apply force to the return lip generally normal to the plane of the panel.

22. A loudspeaker according to any one of claims 13 to 15 , wherein the vibration exciter is adapted to apply force to the return lip generally in the plane of the panel.

23. A loudspeaker according to any one of claims 13 to 15 , wherein the panel is adapted to be resonant to produce an acoustic output.

24. A loudspeaker according to claim 23 , wherein the panel is of the distributed mode kind.

25. A small electronic device having a display screen, and a transparent protective cover over the display screen, wherein the transparent protective cover is a loudspeaker as claimed in any one of claims 13 to 15 .

26. A small electronic device according to claim 25 , wherein the device is a mobile telephone, PDA or the like.

27. A bending wave panel-form loudspeaker having:

a panel;

a lever rigidly coupled to an edge of the panel, said lever having a return member extending generally parallel to the plane of the panel at its end remote from the panel;

a vibration exciter coupled to the return member of the lever to apply bending wave energy to the panel to produce an acoustic output; and

a panel suspension positioned outboard of the lever.