Acoustically enhanced electro-dynamic loudspeakers

Abstract

An electro-dynamic loudspeaker is provided with dampening arrangements that contribute to improved acoustical properties for the electro-dynamic planar loudspeaker. The dampening arrangements include providing a frame having a curved sidewall surface for reducing standing waves. Another design provides for a ferrofluid being disposed between the diaphragm and magnets of the electro-dynamic loudspeaker in order to dampen the resonance frequency of the device. In addition, a diaphragm of an electro-dynamic loudspeaker is provided with a short turn of conductor disposed along a fringe zone at an edge of the diaphragm in order to electro-dynamically dampen the edge resonance of the film.

What is claimed is:  
     
         1 . An electro-dynamic loudspeaker, comprising: 
 a frame defining a recessed portion having a pair of sidewalls interconnected by a pair of end walls, at least one of the sidewalls including a plurality of curves along a length of the sidewalls;    a plurality of magnets mounted in the recessed portion of the frame; and    a diaphragm mounted to the frame.    
     
     
         2 . The loudspeaker according to  claim 1 , where the plurality of curves along the length of the at least one of the sidewalls are sinusoidal.  
     
     
         3 . The loudspeaker according to  claim 1 , where the plurality of curves along the length of the at least one of the sidewalls are scalloped.  
     
     
         4 . The loudspeaker according to  claim 1 , where the diaphragm is mounted to the frame by an adhesive.  
     
     
         5 . An electro-dynamic loudspeaker, comprising: 
 a frame defining a recessed portion having a pair of sidewalls interconnected by a pair of end walls, the sidewalls being non-parallel to one another;    a plurality of magnets mounted in the recessed portion of the frame; and    a diaphragm attached to the frame.    
     
     
         6 . The loudspeaker according to  claim 5 , where one of the pair of sidewalls of the recessed portion of the frame is angled relative to the other of the pair of sidewalls.  
     
     
         7 . An electro-dynamic loudspeaker, comprising: 
 a frame;    a plurality of magnets mounted to the frame;    a diaphragm mounted to the frame; and    a ferrofluid disposed between the diaphragm and the magnets.    
     
     
         8 . The loudspeaker according to  claim 7 , further comprising means for maintaining the ferrofluid on the plurality of magnets.  
     
     
         9 . The loudspeaker according to  claim 7 , further comprising a wall structure surrounding the plurality of magnets.  
     
     
         10 . An electro-dynamic loudspeaker, comprising: 
 a frame;    a plurality of magnets mounted to the frame;    a diaphragm mounted to the frame; and    means disposed between the diaphragm and the magnets for dampening vibration of the diaphragm.    
     
     
         11 . The loudspeaker according to  claim 10 , where the means disposed between the diaphragm and the magnets is a ferrofluid.  
     
     
         12 . The loudspeaker according to  claim 11 , further comprising means for maintaining the ferrofluid on the plurality of magnets.  
     
     
         13 . The loudspeaker according to  claim 10 , further comprising a wall structure surrounding the plurality of magnets.  
     
     
         14 . A method of dampening vibration of a diaphragm of an electro-dynamic loudspeaker, comprising the steps of: 
 mounting at least one magnet in a frame;    placing ferrofluid on an upper surface of the at least one magnet; and    mounting a diaphragm, with an electric circuit thereon, to the frame such that the ferrofluid is in contact with the diaphragm.    
     
     
         15 . The method according to  claim 14 , where the at least one magnet is mounted inside of a wall structure that surrounds the magnet.  
     
     
         16 . An electro-dynamic loudspeaker, comprising: 
 a frame;    at least one magnet mounted to the frame;    a diaphragm mounted to the frame, the diaphragm including a conductor mounted to a film material; and    a shorted turn of conductor disposed along a fringe zone at an edge of the diaphragm.    
     
     
         17 . The loudspeaker according to  claim 16 , further comprising a second shorted turn of conductor disposed on an opposite side of the diaphragm form the shorted turn of conductor.  
     
     
         18 . An electro-dynamic loudspeaker, comprising: 
 a frame;    at least one magnet mounted to the frame;    a diaphragm mounted to the frame, the diaphragm including a conductor mounted to a film material, the film material being a piezoelectric material; and    an undriven conductor applied to both sides of the film material.    
     
     
         19 . The loudspeaker according to  claim 18 , where the undriven conductor is disposed in a fringe zone at an edge of the film material.  
     
     
         20 . An electro-dynamic loudspeaker, comprising: 
 a frame;    at least one magnet mounted to the frame;    a diaphragm mounted to the frame, the diaphragm including a conductor mounted to a film material, the film material being a piezoelectric material; and    conductor means for providing an electric current in a fringe zone at an edge of the diaphragm.