Patent ID: 6212284
Filing Date: 2001-04-03
Classification: H04R

Abstract:
A sound reproduction device comprising;a first membrane (15) for reproducing low-frequency sounds, the first membrane having a front surface (28) and a rear surface (29),a drive device (14), which drives at least the first membrane (15) and is disposed spaced axially apart from it,fastening means (13) for the reciprocal connection of the first membrane (15) and the drive device (14),a displacement volume (37, 37') which is disposed in front of the front surface (28) or in front of the rear surface (29),a closed damping volume (30), which is constituted by walls of a housing (12) and the first membrane (15),the displacement volume (37, 37'), which adjoins the front surface (28) or the rear surface (29) of the first membrane (15) remote from the damping volume, is closed except for at least one opening (35),the cross sectional area of all of the openings (35) is significantly smaller than the cross sectional area (35) of the first membrane (15),an open sound guidance conduit (34) adjoins each opening (35) and its cross section corresponds essentially to the cross sectional area of the opening (35) to which it is connected; andwherein when there is a deflection of the first membrane (15) to one side, the displacement volume is calculated according to the following formula:displacement volume<=effective membrane diameter.sup.3.times.0.06,andwherein the length of the sound guidance conduit is less than or equal to one-eighth (.ltoreq..lambda./8) of a desired upper cross-over frequency;and further wherein the sound reproduction device comprisesan additional membrane (15') disposed spaced axially apart from the first membrane (15), and whereinthe drive device (14), which also drives the additional membrane (15'), is disposed between the two membranes (15, 15').