Loudspeaker with undulated membrane
A loudspeaker provided with a frame ( 101 ), a membrane ( 103 ) and a drive unit ( 105 ). The membrane has an outer circumferential edge ( 104 a ) suspended from the frame and an inner circumferential edge ( 104 b ). The drive unit has a stationary part ( 106 a ) secured to the frame and a translatable part ( 106 b ) provided with a coil support ( 108 b ) secured to the inner circumferential edge of the membrane. The membrane includes a membrane body ( 104 ) which, viewed in a circumferential direction, has a pattern of folds radially extending between the inner circumferential edge and the flat outer circumferential edge of the membrane. The folds have a depth (d), which increases from the edges ( 104 a, 104 b ) towards an area ( 104 A) situated between both edges. In this area, the folds are provided with faces ( 204 C), to which a spider ( 111 ) of the loudspeaker is secured. This loudspeaker combines a small height with a large stroke of the membrane.
1. A loudspeaker provided with a frame ( 101 ), a membrane ( 103 ) and a drive unit ( 105 ), the membrane having an outer circumferential edge suspended from the frame and an inner circumferential edge, the drive unit having a stationary part secured to the frame and a translatable part secured to the inner circumferential edge of the membrane, wherein the membrane includes a membrane body ( 104 ) which, viewed in a circumferential direction, has a pattern of folds ( 104 c ) radially extending between the inner circumferential edge and the outer circumferential edge of the membrane, which folds, viewed from the membrane body towards the driving unit in a direction substantially perpendicular to the membrane, have a depth (d) which increases from said edges towards an area ( 104 A) situated between the inner circumferential edge and the outer circumferential edge, in which area the folds are provided with faces ( 104 C), wherein a suspension means is provided which is secured to the frame and said faces.
2. A loudspeaker as claimed in claim 1 , wherein the inner circumferential edge and the outer circumferential edge are substantially flat edges.
3. A loudspeaker as claimed in claim 1 , wherein the inner circumferential edge and the outer circumferential edge of the membrane are situated in substantially coinciding planes or zones.
4. A loudspeaker as claimed in claim 2 , wherein the membrane body is a slightly concave body, the substantially flat inner circumferential edge and the substantially flat outer circumferential edge being situated in parallel planes.
5. A loudspeaker as claimed in claim 1 , wherein the suspension means is a spider.
6. A loudspeaker as claimed in claim 2 , wherein the substantially flat inner circumferential edge of the membrane is secured to a coil support of the translatable part of the driving unit.
7. A loudspeaker as claimed in claim 2 , wherein the folds have a depth which, measured from the membrane body, smoothly decreases from the area in which the folds are provided with faces towards the substantially flat outer circumferential edge of the membrane.
8. A loudspeaker as claimed in claim 2 , wherein the folds have a depth which, measured from the membrane body, smoothly decreases from the area in which the folds are provided with faces towards the substantially flat inner circumferential edge of the membrane.
9. A loudspeaker as claimed in claim 1 , wherein the pattern of folds is a regular pattern, viewed in a circumferential direction and/or radial direction.