Panel-form loudspeaker
AssigneeThe Secretary of State for Defense in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
InventorKenneth Harry Heron
Life of this patent
Estimating the term…
Abstract
A panel-form loudspeaker has a resonant multi-mode radiator panel which is excited at frequencies above the fundamental frequency and the coincidence frequency of the panel to provide high radiation efficiency through multi-modal motions within the panel, in contrast to the pistonic motions required of conventional loudspeakers. The radiator panel is a skinned composite with a honeycomb or similar core and must be such that it has a ratio of bending stiffness to the third power of panel mass per unit area (in mks units) of at least 10 and preferably at least 100. An aluminum skinned, aluminum honeycomb cored composite can meet this more severe criterion easily.
Claims24
A panel-form loudspeaker comprising:
- a resonant multi-mode radiator element forming a panel wherein said panel is such as to have ratio of bending stiffness (B), in all orientations, to the cube power of panel mass per unit surface area (.mu.) of at least 10 and wherein the panel has no planform dimension less than half the bending wavelength at the lowest frequency of a working frequency band;
- a mounting means which supports the panel or attaches it to a supporting body, in a free undamped manner;
- and an electromechanical drive means coupled to the panel which serves to excite a multi-modal resonance in the panel in response to an electrical input within a working frequency band for the loudspeaker.
A panel-form loudspeaker comprising:
- a panel comprising at least a first skin, at least a second skin, and at least a core, said core interconnecting and spacing apart said first and second skins;
- a panel mount supporting the panel for vibration;
- and
- an electromagnetic exciter, coupled to the panel and responsive to an electrical input, which serves to excite a multi-modal resonance in the panel, said electrical input having a working frequency band for the loudspeaker, wherein said panel core has a shear modulus G which is not less than the value given by the relationship ##EQU1## where d is the depth of the panel core, .mu. is the mass per unit surface area of the panel and c is the speed of sound in air.
A panel-form loudspeaker for converting an electrical input signal into an acoustic output, said electrical input signal having a working frequency band, said loudspeaker comprising:
- a panel comprising at least a first skin, at least a second skin, and at least a core, said core interconnecting and spacing apart said first and second skins, the panel has a ratio of bending stiffness (B), in all orientations, to the cube power of panel mass per unit surface area (.mu.) of at least 10, has a minimum planar dimension not less than half a bending wavelength at a lowest frequency of said working frequency band, and has a shear modulus G which is not less than the value given by the relationship ##EQU2## where d is the depth of the panel core, .mu. is the mass per unit surface area of the panel and c is the speed of sound in air;
- a mounting means for supporting the panel for vibration;
- and
- an electromagnetic exciter, coupled to the panel and responsive to said electrical input, for exciting a multi-modal resonance in the panel.
A panel-form loudspeaker comprising:
- a panel comprising at least a first skin, at least a second skin, and at least a core, said core interconnecting and spacing apart said first and second skins;
- a mounting means for supporting the panel for vibration;
- and
- an electromagnetic exciter means, coupled to the panel and responsive to an electrical input, for exciting a multi-modal resonance in the panel, said electrical input having a working frequency band for the loudspeaker, wherein said panel core has a shear modulus G which is not less than the value given by the d relationship ##EQU3## where d is the depth of the panel core, .mu. is the mass per unit surface area of the panel and c is the speed of sound in air.
Dependencies are inferred from the claim text.