Flat loudspeaker with enhanced low frequency

Claim 2

In a diaphragm for flat loudspeakers, means to emphasize the low frequencies and to change the shade and colour of the sound, comprising a first plate-like member having a substantially flat front face and a rear face defining a figure portion and a first marginal vibration damping portion which substantially circumscribes said figure portion, said figure portion being of non-uniform thickness and having a zone of maximum thickness for receiving vibrations from a driving unit, at least one part of said rear face, in the zone corresponding to said first marginal vibration damping portion, being connected to a second plate-like member at least a portion of which projects beyond said first marginal vibration damping portion, said second plate-like member being capable of collecting low frequency vibrations which are capable of entering said first marginal vibration damping portion.

Claim 3

The diaphragm of claim 1, wherein said second plate-like member covers and is connected to the entire zone of said first marginal vibration damping portion and projects beyond the periphery of said first plate-like member.

Claim 4

The diaphragm of claim 2, wherein said second plate-like member has a cut-out central portion, defining an endless lateral wall, the periphery of said figure portion defining an endless side wall, and said side wall and lateral wall are coplanar.

Claim 5

The diaphragm of claim 3, wherein said second plate-like member is of conglomerated wood and its endless lateral wall as well as its periphery are sealed.

Claim 6

The diaphragm of claim 1, wherein said first plate-like member is integral with an additional portion of smaller size, which includes a further figure portion surrounded by a further pertinent marginal vibration damping portion, said further pertinent marginal vibration damping portion is acoustically isolated from said first marginal vibration damping portion by means of a channel member filled with a resilient material.

Claim 7

The diaphragm of claim 1, wherein said first plate-like member is made of a foamed plastic.

Claim 8

The diaphragm of claim 1, wherein said second plate-like member forms part of a resonance box comprising a first plate member connected to one part of said rear face in the zone corresponding to said first marginal vibration damping portion and projecting beyond said first plate-like member, said first plate member having a peripheral portion, a perimetrical cross band member connected to said peripheral portion and a second plate member connected to said perimetrical cross band member; each of said first and second plate members having a cutout portion, said cutout portions being substantially aligned; the cutout portion of said second plate member being of smaller area than said cutout portion of said first plate member; said first plate member, perimetrical cross band member, and second plate member defining said resonance box; said second plate member having an internal free edge portion overhanging said figure portion of said plate-like member.

Claim 9

The diaphragm of claim 7, wherein said second plate member includes holes connecting the inside of said resonance box with the outside.

Claim 10

The diaphragm of claim 7, wherein said perimetrical cross band member includes holes connecting the inside of said resonance box with the outside.

Claim 11

The diaphragm of claim 7, wherein said free edge portion overhangs the entire periphery of said figure portion.