Abstract:
The membrane of a loudspeaker, which is driven on a limited part of the membrane, does not move completely like the tone current. For example, a cone, which is driven in the top, provides more accurate driving by also being driven in the periphery from the drive system back where the movement of the sound coil also is taken out. The driving can e.g. be distributed with a cone of net. With separate sound coils from the front side and back side of the driving system, the loudspeaker properties can be optimised. The biggest benefit is achieved with a long loudspeaker where the movement is taken out from the back side of the long drive system and distributed with plates, cones and wavy walls to a bulgy membrane edges.

Description:
PRIOR APPLICATION  
       [0001]    This is a continuation-in-part patent application that claims priority from US patent application Ser. No. 11/569,672 filed 27 Nov. 2006 that claims priority from International Application No. PCT/SE2005/000772, filed 25 May 2005, claiming priority from Swedish Patent Application No. 0401365-2, filed 28 May 2004. 
     
    
     BACKGROUND AND SUMMARY OF THE INVENTION  
       [0002]    There is too much sound produced today causes damage to the ear. In the ear there are muscles which can be tired. Therefore, after a period of exposure, injures may arise from reasonable high sound levels. 
         [0003]    One object of the present invention is to produce a sound system which with high quality only gives off the sound level needed at all places in the whole space intended. 
         [0004]    A long and narrow loudspeaker along a whole wall has the following advantages: 
         [0005]    The listeners closest to the sound system are all exposed to the same sound levels. 
         [0006]    No or only insignificant reflections arise from the side walls if the room has right angles in the corners. 
         [0007]    The sound pressure drops relatively slowly so that listeners at distance from the loudspeaker maintain a good sound level without the nearest listeners having to be exposed to painfully high levels. 
         [0008]    A section of the loudspeaker only needs to deliver sound to a slice of air in front of the section, which means that the membrane only needs to deliver relatively low sound pressures, which imply small amplitudes. 
         [0009]    The air retains its linear properties, so distortion caused by high sound pressure does not occur. The sound coil movement gets small amplitude, so that the distortion in the driving system will be low. 
         [0010]    If one wants to further improve the propagation of the sound, it can be relatively easily reflected and bent because the material for this will have cylindrical surfaces. Driving systems with reduced force may be used e. g. reduced magnetic field in electro-dynamic driving system. Even geomagnetic fields may be used if they are at first concentrated. 
         [0011]    A conventional electro-dynamic loudspeaker has the cone as membrane. This is driven by the coil with current in the ring formed air gape with the magnetic flux from the magnetic device, which sits in the basket bottom, which the membrane edges via the outer suspension sits in the basket edges. 
         [0012]    The basic problem of conventional loudspeakers is that the cone in order to produce bas tones shall be large, at which the treble tones at the best make a propagating wave outwards in the cone. 
         [0013]    In order to reduce the problem, a driving unit may be used where the movement is taken out from two places. The membrane is then driven at the center from the driving unit outer end, while the membrane is driven at the periphery respective along the edges from the drive unit inner end. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  shows three horizontally placed long and narrow loudspeakers on a wall, which produce angle stereo in the entire room. 
           [0015]      FIG. 2  shows a side-view of an example of a horizontally placed long and narrow loudspeaker composed of a number of membranes which together form a half cylinder and a speaker with only one membrane. 
           [0016]      FIG. 3  shows how a long loudspeaker is made of flux catchers of iron plates, which catch geomagnetic fields and via flux conductors distribute the field across long membranes, which conduct the sound current. 
           [0017]      FIG. 4  shows how long, narrow and bent loudspeakers placed along and across walls in a winding passage give winding phase front but yet smooth, sound level, which reduces strong and unnecessary scattering. 
           [0018]      FIG. 5  shows how an anisotropic prism redirects sound. 
           [0019]      FIG. 6  shows a principle of the membrane, drive units and drive distributor of the present invention. 
           [0020]      FIG. 7  shows the details in a round loudspeaker that is provided with drive distributor. 
           [0021]      FIG. 8  shows the details in an elongate loudspeaker provided with drive distributor and a long loudspeaker driven by  4  bands in magnetic air gaps. 
           [0022]      FIG. 9  shows an alternative embodiment including driving units with cog plate. 
           [0023]      FIG. 10  shows another alternative embodiment including a driving unit with two separate coils. 
           [0024]      FIG. 11  shows a driving unit with  2  coils on the same tube. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  shows a long, narrow loudspeaker  1  on a wall. The loudspeaker follows the waff and gives off the sound in a straight forward direction. The loudspeaker  2  has the left end moved forward, causing the sound to be somewhat directed to the right. This gives a stereo sound with two distinct directions as to where the sound is coming from and is much more independent of ones location in the room than would be expected using concentrated loudspeakers. 
         [0026]    If the loudspeakers encroach on the space one can mount loudspeaker elements  3 ,  4 ,  5  and  6  directed in the same angle but in a row against the wall. These elements are in themselves long and narrow loudspeakers, which mean that the membrane is long and narrow. The sound is delayed between the loudspeaker elements with e. g. an electronic delay  7  between them, so that the wave front is straight but directed obliquely forward. The signal enters the first element by an amplifier  8  and to every element there are suitable amplifiers  9 . Between the elements there is a partition wall  10 . All the listeners  11 ,  12  and  13  now receive a sound source coming from the right. In order to more exactly adapt the waves between the elements they can be made with different widths. 
         [0027]    It is quite easy to increase the distribution of sound from a long and narrow loudspeaker, even to the extent that it becomes circular, which is shown in  FIG. 2  as a cross-section. There are at first long parallel membranes  16 , which direct the sound respectively in their own direction. A long preferable permanent magnet  17  feed its flux from its own long side, which lies against the one side on an equally long flux distributing rod  18 , to the middle line on an oblique made thin side of a long plate  19 . Half the flux goes via one slanting edge and an air gap  20  to a similar long plate in a similar position, but slightly rotated, forming an air gap of uniform width. The magnetic field goes out through the other slanting edge and passes a similar air gap to a profiled long plate  22  also with slanting edges. The other slanting edge of the profiled long plate  22  faces in the same direction as the others side of the flux distributing rod  18 , making it possible for the square rods  23  to pass, without air gaps, the magnetic field to that side and close the magnetic field. 
         [0028]    Even the other slanting edge of the long plate  19  on the permanent magnet has a similar magnetic circuit, whose magnetic field is fed back via the other ends of the square rods  23 . 
         [0029]    In the air gaps there are conductors formed as T-profiles  24  with slits in the roof of the T, in order to prevent current from passing there. The roof of the T-profiles is fastened to the membranes  16 , whose edges with elastic strips  25  are affixed in supports on the outside of the long plate  19 . The outermost strips  27  are affixed in nonmagnetic struts  28  on the ends of the square rods  23 . 
         [0030]    The sound currents are fed into the upper conductors and return through the lower conductors. 
         [0031]    The permanent magnets can be placed anywhere in the magnetic circuits e. g. two permanent magnets  31  and  32  in the square rods or an permanent magnet  33  in the long plates  19  with beveled sides. 
         [0032]    The magnetic flux can also be obtained by an electric current, which goes in a coil, which goes longitudinally around the profiled flux distributing rod  18 , and has the cross section  34  and  35 . The construction principle is flexible, so that a round propagating loudspeaker, which e. g. can go from floor to ceiling, is illustrated by an arch  29 , which is joined to a ring, on which many long plates with beveled sides are fixed. How the construction is continued may be easily perceived and continues in the upper part  36 , but is broken by an example of a simple element, which will be described later. In the round propagating loudspeaker the permanent magnets  37  can be placed in the long plate  19  or a form of torus coil can be used going from the center with the cross-section  38  and back into the supports with the cross-section  39 . The sound currents then go through the conductors and returns in the long plate  19 . 
         [0033]    The membranes can be made stiff by building them as trusses. The membrane  16  can be made bent by placing a beam  40  outside the center line and a further plate  41  upon and fixed to the longitudinal edges of the plates. It may also be placed ribs  42  between the plates. 
         [0034]    The mentioned simple loudspeaker has a permanent magnet  43 , which forces the magnetic field across into an iron rod  44  and out into two parallel air gaps at the sides. In the air gaps there are conductors of L-profiles  45  and  46  with slits in the joins to a plane membrane  47 . The magnetic field returns with the mentioned iron structure, which let the sound waves pass. Many loudspeakers can form a cylinder. 
         [0035]    A long and narrow loudspeaker, which uses the geomagnetic field will be effective because the magnetic field can be concentrated. Furthermore, the sound pressure can be amplified by a cylindrical exponential horn. 
         [0036]    In detail the loud speaker can be made e. g. as on  FIG. 3 . The earth&#39;s magnetic field  51  is caught by a first flux catcher  52 , which consists of an iron plate. The flux conductor  54  conveys the magnetic field to flux plates  55  and  56  where the flux conductor is of decreasing thickness. The magnet field passes air gaps  57  and  58  in which horizontal membranes  59  and  60  are placed and reaches the flux plates  61  and  62 . There the flux goes over to flux conductors  63  and  64  so that in junction  65  they combine and head towards the flux conductor  66 . This goes to a second flux catcher  67  from which the magnetic field  68  exits. The membranes are fed with longitudinal sound currents. The flux catcher can be placed on walls, roofs, masts, in the ground, in wells and mining holes. 
         [0037]    This loudspeaker can above all be used where flux unintentionally has arisen. Railway rails in combination with steel roofs over platforms provide the possibility to give the travelers information, which they interpret as coming from an accompanying guide. Also natural flux catchers like ore are usable. 
         [0038]    One method to combine sound in a broad corridor with both curves and straights is shown in  FIG. 4 . The corridor begins lowest down with a straight part  70 , where a cylindrical, parabolic reflector  71  is placed on the left wall with a straight loudspeaker  72  in the focus line. Where the corridor turns to the right  73  there is a long bent loudspeaker  74  built of weakly bent or straight loudspeaker elements. A straight loudspeaker would produce a sound level, which decreases with distance. The bending focuses the sound, giving a constant sound level at least within a certain range, which better fits with the plain wave in the earlier part  70 , but also to the next part  75 , which is straight and has a cylindrical, parabolic reflector  76  and a long loudspeaker  77  to the left. 
         [0039]    The next part  78  has a curve to the left. There situated to the left is a long forward bent loudspeaker  79  with e. g. a quarter of a circle rounded membrane  80  and concentrates the sound a distance out from the opposite bent wall, making the sound level almost constant. 
         [0040]    The almost constant sound level fits to the plane wave in the straight part  75 , but also to the last part  81 , which is straight and has a cylindrical, parabolic reflector  82  and a straight loudspeaker  83  to the left. 
         [0041]    Sound can in principal be focused through a prism where the material is within special cylinders with arces as generatrixes. The aim can also be to guide away sound e. g. if it is disturbing. Then the cross-section of the prism can be triangular. The acoustic lens can be made of cellular plastic. This is an isotropic material. An acoustic lens where the material is anisotropic, guides the sound better in the desired direction as opposed to perpendicular to it, as shown in  FIG. 5 . As seen from the perspective of the loudspeaker, it is built of a large convex cylindrical membrane  93 , which receives the sound waves from a long and narrow loudspeaker  94  and guides the sound forward by sound conductors  95  of e. g. plates, rods, tubes, grinders or beams to a concave cylindrical membrane  96 . Because the sound conductors are longer against the edges of the membrane and the sound velocity in those are higher than in the air, the wave front will be changed from cylindrical to e. g. plain when it propagates out in the air. 
         [0042]    It is not possible to prevent the sound from also reflecting from the acoustic lens. If there is a wall behind the loudspeaker it may be necessary to provide it with sound damping material  97 . Separately carried sound damping material  98  in the cells between the membranes can be an advantage. 
         [0043]    With reference to  FIGS. 6-11 , the loudspeakers are described with the membrane turned upwards and as a rule with double cross-section. 
         [0044]      FIG. 6  shows a simplified cross-section of a long loudspeaker with a driving unit  101 . This can be electro-dynamic, piezoelectric, electromagnetic, and perhaps electrostatic or pneumatic systems. The membrane  102  is in the center driven by a upper drive holder  103  from the drive unit and is driven by a lower drive holder  104  from the drive unit via a lower drive distributor  105  in the form of a plate outwards to the edges of the long membrane  102 . 
         [0045]    One can get driving in the edges with different transferring ways for the movement.  FIG. 6A  shows that one way is to go down from the drive unit center with drive part and then let the movement with an arm  106  turn out to the membrane edges. Another drive part  107  can go outside and down side the drive unit and turn out to the membrane edges. A beam connected horizontally reduces a bending along a middle line of the membrane. 
         [0046]    An application to drive at the edges is a round loudspeaker as in  FIG. 7 . There is a drive unit  101  with a large upper washer  109  and a similar lower washer with a vertical magnetizes permanent magnetic ring  110  in between. Through the washer holes go with play a iron cylinder  11 , which has the height of the drive unit and form two ring formed air gaps where the magnetic field goes inward in the one air gap an outwards in the other air gap. 
         [0047]    In the air gaps there are coils  112  and  113  on a tube, which do not short voltages. From the upper coil  112  the tube goes further as an upper drive holder  103  up to a bulged membrane  114 , which also spreads the treble tones. From the lower coil  113  the tube goes down as a lower drive holder  104  to the bottom of a large net cone  115 , which upper edge is close to the membrane periphery. 
         [0048]    The iron cylinder  111  stands on a cylinder  116  of different material. It stands in order on the bottom in a basket  117 . 
         [0049]    In the figure the drive unit with colons  121  is, through holes in the net cone  115 , put on the basket bottom. But one can lead in holders in holes to the basket sides and even through holes in the drive holder  103  and  104  directly to the cylinder  111 . 
         [0050]    The driving of the center of the membrane can be improved with further one net cone  122  from the drive holder  103  up under the membrane  114 . The coils shall be feed by tone current in opposite directions. 
         [0051]    If the tube between the coils are removed the net cone  115  will be independent driven. The current in the upper coil can be delayed in order to make the movement of the membrane center going synchronized with the movement of the periphery. 
         [0052]    There are many possible variations of the principle. Here are a lot of devices given. 
         [0053]    Two ordinary electro-dynamic drive units may be coaxially put together and their coil tubes are used as upper and lower drive via net cones. If necessary a delay of the tone current can be made. 
         [0054]    The can be variations in the performance.  FIG. 8  shows a cross-section of a long drive unit similar to  FIG. 6 , which contain a long permanent magnet  43  with the magnetization across and vertically and the one pole at a square rod  44 , which are at the left and right of the air gaps  123  to the flat iron  124 . The magnetic circuits are closed by cross going blocks  125 , which are sitting over the permanent magnet  43  and connect mechanically and magnetically the flat iron  124 . 
         [0055]    In the air gap  123  conductors of broad bands  129  with slits across both the lower and upper edges to prevent the tone current to go there. The tips in the upper edge go up besides the blocks  125  and become upper drive holder  103  while the tips in the lower edge become lower drive holder  104 . 
         [0056]    The upper drive holder  103  goes to the center line of the membrane  102 , while the lower drive holder  104  via e.g. drive plates  126  go to the edges of the membrane and a small distance before. They become both a rib, which reinforce the membrane. On the left side is used a drive cone  127 , which is elliptic at the lower drive holder. If the cone is made of net it will not be bent by the air and move the air. 
         [0057]    If the cross blocks in  FIG. 8  are exchanged to square rod  128  with the same dimensions as the square rod  44  and if the rods and permanent magnets are given the same width and if the space between the permanent magnet and the flat irons with supporting material, there will be 2 upper and 2 lower air gaps  123 . In the air gaps bands with slits are placed. The slits are upper and lower drive holders. Now the current in the upper coil can be delayed to improve the treble. The membrane is along the edges provided with flexible upper suspensions  130  fixed in a long basket of cross going bottom ribs  131 , along going carrying bars  132 , cross going drive unit support  133 , along going side plates  134 , where the upper suspension  130  sits between the tips in the lower drive holder  104 , which has lower suspensions  136  to the bottom ribs  131 . 
         [0058]      FIG. 9  shows a cylindrically permanent magnet  140  with the poles in its ends, has an iron cylinder  141  on its upper pole, which has air gaps  142  to an outside sitting iron tube  139 , which lower inner is filled with a cog plate  143  of iron, on which the permanent magnet stand. 
         [0059]    In the air gap there is a coil wounded on an isolated tube, which upper end is upper drive holder  103  on  FIG. 7 . The lower end changes to rods, which pass the cog plate cogs and become lower drive holder  104 . 
         [0060]      FIG. 10  shows a cylindrical magnet  140  with the poles in its ends surrounded by a thin non-magnetically supporting ring  144 . The permanent magnet  140  stand on a short iron cylinder  145  and upon it stands a similar cylinder  146 . The tube  139  reach the outer sides of the cylinders  145  and  146  providing air gaps for an upper coil  147  and lower coil  148  with drive part  104  passing e.g. a cog plate. 
         [0061]    On  FIG. 11  is shown how the nonmagnetic tube  144  is removed from  FIG. 10  and the coils are wounded on the same tube  150 , so that they drive together. 
         [0062]    The movement of the membrane center can be delayed by e.g. folded strips  160 ,  161  supported by pins  162  under the drive holder. 
         [0063]    While the present invention has been described in accordance with preferred compositions and embodiments, it is to be understood that certain substitutions and alterations may be made thereto without departing from the spirit and scope of the following claims.