Resonant panel-form loudspeaker

1. A loudspeaker assembly comprising a visual display screen, a panel-form member positioned adjacent to the display screen and at least a portion of which is transparent and through which the display screen is visible, and at least one vibration exciting transducer mounted to an edge or marginal portion of the panel-form member to cause the panel-form member to act as an acoustic radiator, wherein the panel-form member is adapted to be resonant when excited at audio frequencies to undergo bending wave vibration, wherein the vibration exciting transducer is adapted to apply bending wave energy to the panel-form member to cause it to undergo bending wave vibration and resonate to act as an acoustic radiator when resonating, and wherein one or more marginal portions of the panel-form member are clamped or restrained.

2. A loudspeaker assembly according to claim 1 , wherein the whole of the resonant panel-form member is transparent.

3. A loudspeaker assembly as claimed in claim 1 or claim 2 , wherein the panel-form member is of plastics.

4. A loudspeaker assembly as claimed in claim 1 or claim 2 , wherein the panel-form member is selected from the group consisting of polystyrene, polycarbonate, glass and a laminate of plastics and glass.

5. A loudspeaker assembly according to claim 1 or claim 2 , wherein the panel-form member is a laminate comprising a core of plastics or aerogel with skins of glass.

6. A loudspeaker assembly according to claim 1 or claim 2 , comprising more than one vibration exciting transducer.

7. A loudspeaker assembly according to claim 1 or claim 2 , comprising vibration exciting transducers mounted in pairs to at least one edge or marginal portion of the panel-form member.

8. A loudspeaker assembly according to claim 7 , wherein the vibration exciting transducers are coupled directly to the panel-form member.

9. A loudspeaker assembly according to claim 1 or claim 2 , wherein the vibration exciting transducer is coupled directly to the panel-form member.

10. A loudspeaker assembly according to claim 1 or claim 2 , wherein the vibration exciting transducer is electrodynamic.

11. A loudspeaker assembly according to claim 1 or claim 2 , wherein the vibration exciting transducer is inertial.

12. A loudspeaker assembly according to claim 1 or claim 2 , comprising an associated support for the loudspeaker assembly.

13. A loudspeaker assembly according to claim 12 , wherein the associated support is a frame or chassis.

14. A loudspeaker assembly according to claim 13 , wherein the resonant panel-form member is resiliently supported on the associated support.

15. A loudspeaker assembly according to claim 14 , wherein the vibration exciting transducer is resiliently mounted in the associated support.

16. A loudspeaker assembly according to claim 14 , wherein the panel-form member is rectangular, and wherein a resilient panel support extends along at least three adjacent edges of the panel-form member.

17. A loudspeaker assembly according to claim 15 , wherein the panel-form member is rectangular, and wherein a resilient panel support extends along at least three adjacent edges of the panel-form member.

18. A loudspeaker assembly according to claim 12 , wherein the vibration exciting transducer is resiliently mounted in the associated support.

19. A loudspeaker assembly according to claim 1 or claim 2 , wherein the vibration exciting transducer comprises a transparent piezoelectric or electret on or in at least a part of the panel-form member.

20. A loudspeaker assembly according to claim 1 or claim 2 , wherein the whole periphery of the panel-form member is mechanically clamped.

21. A loudspeaker assembly according to claim 1 or claim 2 , wherein the panel-form member is mounted in an associated cavity or enclosure enclosing a face of the panel-form member whereby acoustic radiation from the enclosed face is at least partly contained within the enclosure or cavity.

22. A loudspeaker assembly according to claim 21 , wherein the enclosure or cavity is shallow in depth such as to modify the modal behaviour of the panel-form member.

23. A loudspeaker assembly according to claim 1 or claim 2 , wherein the display screen is integral with the panel-form member.

24. A loudspeaker assembly according to claim 23 , wherein the integral display screen comprises a light emitting surface.

25. A loudspeaker assembly according to claim 23 , wherein the integral display screen comprises a light transmitting surface.

26. A loudspeaker assembly according to claim 23 , wherein the integral display screen comprises a light reflective surface.

27. A loudspeaker assembly according to claim 1 or claim 2 , wherein the panel-form member forms the external face of a visual display unit.

28. A loudspeaker assembly according to claim 1 or claim 2 , comprising a polymer-film liquid crystal display bonded or otherwise mounted on the panel-form member.

29. A loudspeaker assembly according to claim 1 , wherein the resonant panel-form member has a user-accessible surface and means on or associated with the surface and responsive to user contact.

30. A loudspeaker assembly according to claim 29 , wherein the user-responsive means on the panel-form member allows instructions or information to be entered, and is selected from the group consisting of pads, areas, switches and buttons.

31. A loudspeaker assembly according to claim 29 , wherein the user-responsive means comprises visible areas on the panel-form member, delineated by printing or labelling, which sense the presence or contact by a user.

32. A loudspeaker assembly according to claim 29 , wherein the user-responsive means comprises metallised user responsive contacts of transparent metal oxide film or thin metal film on the panel-form member.

33. A loudspeaker assembly according to claim 29 , wherein the user responsive means is positioned at the perimeter of the panel-form member.

34. A display screen module comprising a loudspeaker assembly as claimed in claim 1 or claim 2 , and a chassis or frame supporting the display screen and supporting the transparent panel-form member.

35. A telephone receiver comprising a loudspeaker assembly as claimed in claim 1 or claim 2 .

36. A portable personal computer comprising a loudspeaker assembly as claimed in claim 1 or claim 2 .

37. A portable personal computer as claimed in claim 36 , comprising a body having a key pad and a lid adapted to enclose the key pad and carrying a display screen, and wherein the display screen comprises the loudspeaker assembly.