High frequency loudspeaker

A tweeter comprising:

• a light, freely carried thin sandwich plate (3, 20, 39, 60) which can be excited into multiple reflected bending waves,
• at least one driver (1, 13, 14, 15, 26, 27, 28, 40, 41) which makes vibrating contact with and excites the sandwich plate (3, 20, 39, 60),
• wherein the driver (1, 13, 14, 15, 26, 27, 28, 40, 41) is designed to excite at higher sound frequencies, the sandwich plate (3, 20, 39, 60) is designed for the propagation of bending waves with low damping, the sandwich plate (3, 20, 39, 60) is freely supported by holding elements (12, 24, 25, 34, 35) with low damping, and that the holding elements (12, 24, 25, 34, 35) are designed to be low damping at higher sound frequencies,
• wherein the sandwich plate (3) has two thin, hard cover plates (9, 10) with a shear resistant, thin core layer (11) placed between them,
• wherein the core layer (11) contains a spatially different distribution of the elasto-mechanical properties,
• wherein zonal thinning or cutouts (53 to 55) are provided in the core layer or the cover layers,
• wherein the size and arrangement of the zones (53 to 55) is such that a basic pattern is always repeated in a reduced scale,
• wherein the core layer includes a foil which contains periodically repeated bulges (31) produced by embossing,
• wherein the shape, arrangement and direction of the bulges is such that the maximum shear resistance is obtained in all moment directions, and
• wherein the bulges are knobs (49, 50) in the form of a square based, four-sided pyramid, and the knobs (49, 50) are arranged to face in the same direction in strictly periodic, closely adjacent straight rows (47, 48), where each second row (48) alternatingly contains knobs in the opposite direction, and each row (47) is offset by half a knob (49, 50) with respect to the neighboring rows (48).

A tweeter comprising:

• a light, freely carried thin sandwich plate (3, 20, 39, 60) which can be excited into multiple reflected bending waves;
• at least one driver (1, 13, 14, 15, 26, 27, 28, 40, 41) which makes vibrating contact with and excites the sandwich plate (3, 20, 39, 60),
• wherein the driver (1, 13, 14, 15, 26, 27, 28, 40, 41) is designed to excite at higher sound frequencies, the sandwich plate (3, 20, 39, 60) is designed for the propagation of bending waves with low damping, the sandwich plate (3, 20, 39, 60), is freely supported by holding elements (12, 24, 25, 34, 35) with low damping, and that the holding elements (12, 24, 25, 34, 35) are designed to be low damping at higher sound frequencies,
• wherein the sandwich plate (3) has two thin, hard cover plates (9, 10) with a shear resistant, thin core layer (11) placed between them,
• wherein the core layer (11) contains a spatially different distribution of the elasto-mechanical properties,
• wherein zonal thinning or cutouts (53 to 55) are provided in the core layer or the cover layers,
• wherein the size and arrangement of the zones (53 to 55) is such that a basic pattern is always repeated in a reduced scale,
• wherein the core layer includes a foil which contains periodically repeated bulges (31) produced by embossing, and
• wherein the bulges are knobs (49, 50) in the form of a square based, four-sided pyramid, and the knobs (49, 50) are arranged to face in the same direction in strictly periodic, closely adjacent straight rows (47, 48), where each second row (48) alternatingly contains knobs in the opposite direction, and each row (47) is offset by half a knob (49, 50) with respect to the neighboring rows (48).

A tweeter comprising:

• a light, freely carried thin sandwich plate (3, 20, 39, 60) which can be excited into multiple reflected bending waves;
• and
• at least one driver (1, 13, 11, 15, 26, 27, 28, 40, 41) which makes vibrating contact with and excites the sandwich plate (3, 20, 39, 60),
• wherein the driver (1, 13, 11, 15, 26, 27, 28, 40, 41) is designed to excite at higher sound frequencies, the sandwich plate (3, 20, 39, 60) is designed for the propagation of bending waves with low damping, the sandwich plate (3, 20, 39, 60) is freely supported by holding elements (12, 21, 25, 34, 35) with low damping, and that the holding elements (12, 24, 25, 34, 35) are designed to be low damping at higher sound frequencies,
• wherein the sandwich plate (3) has two thin, hard cover plates (9, 10) with a shear resistant, thin core layer (11) placed between them,
• wherein the core layer includes a foil which contains periodically repeated bulges (31) produced by embossing, and
• wherein the bulges are knobs (49, 50) in the form of a square based, four-sided pyramid, and the knobs (49, 50) are arranged to face in the same direction in strictly periodic, closely adjacent straight rows (47, 48), where each second row (48) alternatingly contains knobs in the opposite direction, and each row (47) is offset by half a knob (49, 50) with respect to the neighboring rows (48).