Patent Abstract:
A transducer including a driven element and a magnet assembly. The magnet assembly is coupled to the driven element and includes a first, second and third magnet. Each of the magnets have a first and second magnetic pole. The first magnetic pole of the first magnet and the first magnetic pole of the second magnet being proximate to each other and facing each other thereby defining a magnetic zone therebetween. The second magnetic pole of the third magnet being magnetically proximate to said magnetic zone. The first magnetic poles all having the same polarity, and the second magnetic poles all having the same polarity.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to transducers and more specifically to transducers that use a magnet assembly, such as speaker systems. 
     2. Description of the Related Art 
     A speaker is a type of electro-acoustic transducer, which is a device that converts an electrical audio signal into sound corresponding to the signal. Speakers were invented during the development of telephone systems in the late 1800s. However, it was electronic amplification, initially by way of vacuum tube technology beginning around 1912 that began to make speaker systems practical. The amplified speaker systems were used in radios, phonographs, public address systems and theatre sound systems for talking motion pictures starting in the 1920s. 
     The dynamic speaker, which is widely used today, was invented in 1925 by Edward Kellogg and Chester Rice. A principle of the dynamic speaker is when an electrical audio signal input is applied through a voice coil, which is a coil of wire suspended in a circular gap between the poles of a permanent magnet, the coil is forced to move rapidly back and forth due to Faraday&#39;s law of induction. The movement causes a diaphragm, which is generally conically shaped, and is attached to the coil to move back and forth, thereby inducing movement of the air to create sound waves. 
     Speakers are typically housed in an enclosure and if high quality sound is required, multiple speakers may be mounted in the same enclosure, with each reproducing part of the audio frequency range. In this arrangement the speakers are individually referred to as “drivers” and the entire enclosure is referred to as a speaker or a loudspeaker. Small speakers are found in various devices such as radio and TV receivers, and a host of other devices including phones and computer systems. 
     A problem with electrical transducers in general and speakers in particular is that speaker efficiency, which is defined as the sound power output divided by the electrical power input, is only about 1%. So very little of the electrical energy sent by an amplifier to a typical speaker is converted to acoustic energy. The remainder of the energy is converted to heat, mostly in the voice coil and magnet assembly. The main reason for this is the difficulty of achieving a proper impedance matching between the acoustic impedance of the drive unit and the air it radiates into. The efficiency of speaker drivers varies with frequency as well as the magnetic intensity available to interact with the voice coil. 
     What is needed in the art is an electro-acoustic transducer that can be used with speakers or other devices which has increased effectiveness that will allow more compact designs and will result in more efficient production of sound or movement. 
     SUMMARY OF THE INVENTION 
     The present invention provides a transducer that uses a magnetic assembly having an intense magnetic field. 
     The present invention in one form is a transducer including a driven element and a magnet assembly. The magnet assembly is coupled to the driven element and includes a first, second and third magnet. Each of the magnets have a first and second magnetic pole. The first magnetic pole of the first magnet and the first magnetic pole of the second magnet being proximate to each other and facing each other thereby defining a magnetic zone therebetween. The second magnetic pole of the third magnet being magnetically proximate to said magnetic zone. The first magnetic poles all having the same polarity, and the second magnetic poles all having the same polarity. 
     The present invention in another form is directed to a speaker system including an enclosure and a speaker mounted in the enclosure. The speaker includes a driven element and a magnet assembly. The magnet assembly is coupled to the driven element and includes a first, second, third and fourth magnet. Each of the magnets has a first and second magnetic pole. The first magnetic pole of the first magnet and the first magnetic pole of the second magnet being proximate to each other and facing each other thereby defining a first magnetic zone therebetween. The second magnetic pole of the third magnet and the second magnetic pole of the fourth magnet being proximate to each other and facing each other thereby defining a second magnetic zone therebetween. The first magnetic poles all have the same polarity, and the second magnetic poles all have the same polarity. The first magnetic zone being aligned with the second magnetic zone. 
     The present invention if yet another form is directed to a magnet assembly including a first, second and third magnet. Each of the magnets have a first and second magnetic pole. The first magnetic pole of the first magnet and the first magnetic pole of the second magnet being proximate to each other and facing each other thereby defining a magnetic zone therebetween. The second magnetic pole of the third magnet being magnetically proximate to said magnetic zone. The first magnetic poles all having the same polarity, and the second magnetic poles all having the same polarity. 
     The present invention advantageously produces an intense magnetic field. 
     Another advantage of the present invention is that it allows transducers to efficiently utilize the electrical power provided thereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing, wherein: 
         FIG. 1  is a perspective view of a speaker system that utilizes an embodiment of a transducer of the present invention; 
         FIG. 2  is a cut away view of the speaker system of  FIG. 1 ; 
         FIG. 3  is a cut away view of a speaker of the speaker system of  FIGS. 1 and 2 ; 
         FIG. 4  is a perspective cut away view of another embodiment of a speaker using the transducer of the present invention; 
         FIG. 5  is a planar cut away view of the speaker of  FIG. 4  further illustrating the transducer of the present invention; 
         FIG. 6  is a perspective cut away view of the magnetic assembly of the speakers of  FIGS. 1-5 ; 
         FIG. 7  is a planar cut away view of the magnetic assembly of  FIG. 6 ; 
         FIG. 8  is a schematical view of the magnetic assembly of  FIGS. 6 and 7  illustrating a flow of magnetic flux in the magnetic circuit; 
         FIG. 9  is a schematical view of another embodiment of a magnetic assembly for use with the speakers of  FIGS. 1-5  illustrating a flow of magnetic flux in the magnetic circuit; 
         FIG. 10  is a schematical view of yet another embodiment of a magnetic assembly for use with the speakers of  FIGS. 1-5  illustrating a flow of magnetic flux in the magnetic circuit; 
         FIG. 11  is a schematical view of still yet another embodiment of a magnetic assembly for use with the speakers of  FIGS. 1-5  illustrating a flow of magnetic flux in the magnetic circuit; 
         FIG. 12  is a perspective cut away view of an embodiment of a planar transducer in the form of a planar speaker having a magnetic assembly of the present invention; 
         FIG. 13  is a planar cut away view of the speaker of  FIG. 12 ; 
         FIG. 14  is another schematical view of a magnetic assembly for use as a transducer of the present invention illustrating the magnetic flux of the magnetic circuit; 
         FIG. 15  illustrates a closer view of flux lines associated with the air gap of magnetic assembly of the present invention; 
         FIG. 16  illustrates a closer view of flux lines associated with the air gap of magnetic assembly of  FIG. 11 ; 
         FIG. 17  illustrates a geometry of another embodiment of the present invention; 
         FIG. 18  illustrates the configuration of the prior art and the accompanying asymmetric flux lines in the air gap; 
         FIG. 19  illustrates a geometry of another embodiment of the present invention; 
         FIG. 20  illustrates a geometry of yet another embodiment of the present invention; and 
         FIG. 21  illustrates a geometry of still yet another embodiment of the present invention. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to  FIGS. 1 and 2 , there is shown a speaker system  10  including an enclosure  12  and a transducer  14  in the form of an acoustic speaker  14 . Speaker  14  includes a driven element  16 - 20  that is a speaker diaphragm  16  or cone  16 , a collar  18  and a voice coil  20 . Diaphragm  16  is suspended around its periphery and is moved by collar  18  to produce movements of air to thereby produce sound. Voice coil  20  is a winding of wire coupled to the collar  18  that is positioned in a magnetic field of a magnet assembly  22 . 
     Now additionally referring to  FIG. 3 , there is shown a cut away view of speaker  14  showing more details of magnet assembly  22  which includes ferrous members  24 ,  26 A,  26 B magnets  28 ,  30 ,  36  and  38 , and ferrous members  32  and  34 . Ferrous members  24 ,  26 A and  26 B together have a combined shape that is similar to a nearly closed C-shape, with collar  18  passing therethrough. Ferrous members  24 ,  26 A and  26 B are arranged and shaped in order to largely contain and direct flux from magnets  28 ,  30 ,  36  and  38 , all of which have a circular form. Ferrous members  32  and  34  can also be thought of as being magnetic zones  32  and  34  that are formed due to the orientation of the magnets in contact with the respective ferrous members  32  and  34 . 
     Now, additionally referring to  FIGS. 4 and 5 , there is illustrated another embodiment of a speaker  114 . Similar items in the various embodiments have a multiple of  100  associated with its reference number and the descriptions of one corresponds generally to the description of the other, with any differences being specifically discussed. 
     Now, additionally referring to  FIGS. 6 and 7  there are shown some additional details of magnet assembly  22 . An air gap  40  is illustrated existing between ferrous members  32  and  34 , which is where the intensity of the magnetic field is directed and has its most intense focus. The magnetic field strength in this region may be 2 Tesla, or 3 Tesla, or even 4 Tesla, with even higher levels possible. Such a high magnetic field strength will cause the current passing through voice coil  20  to have a much greater effect, to thereby increase the efficiency of transducer  14 . The magnetic pole orientation if illustrated on the right side of  FIGS. 6 and 7  showing how the poles are arranged in a bucking fashion and will be held in place by the assembly of ferrous members  24 ,  26 A and  26 B with fasteners, not illustrated. The ring magnets  28 ,  30 ,  36  and  38  may individually have approximately the same field strength, or ring magnets  28  and  30  may have a higher magnetic field density to compensate for their smaller diameter relative to magnets  36  and  38 . 
     Now, additionally referring to  FIG. 8 , there is shown a magnet assembly  122 , which can be understood to be similar to magnet assembly  22  and illustrates the magnetic circuit thereof. The lines of flux are shown and it can be seen that the highest intensity, illustrated by the closeness of the flux lines, occurs in air gap  140 , particularly where ferrous members  132  and  134  are aligned with each other. The field lines are generally and even substantially symmetrical in air gap  140 . The construct of ferrous members  124 ,  126 A and  126 B are optimized to substantially contain and direct the magnetic flux lines to thereby largely shield the surrounding environment from being influenced by the magnetic filed arranged in magnet assembly  122 . The magnetic field lines in ferrous members  132  and  134 , can be considered magnetic zones with the area or zone therebetween in air gap  140  having a very intense free air magnetic intensity. 
     Now, additionally referring to  FIGS. 9-11 , there are illustrated different embodiments of the present invention illustrating variations of possible magnetic circuits that are contemplated that result in the desired high magnetic field strength in air gap  140 ,  440 . The magnetic field symmetry in air gap  140  is nearly absolute and will vary only by the minor variations in the materials used and dimensional considerations. The magnetic field symmetry in air gap  440  is still substantially symmetric in a vertical direction and is substantially symmetrical in a horizontal direction, directly laterally to the right of ferrous member  432 . The magnetic field symmetry is still generally symmetrical in directions departing from the lateral outward direction from ferrous member  432 . 
     Now, additionally referring to  FIGS. 12 and 13  there are illustrated another embodiment of the present invention of a transducer  514  in the form of a planar speaker  514 . Magnets  528 ,  530 ,  536  and  538  are here substantially linear and yet the construct is such that the operation is similar to the previously discussed embodiments. The coil  520  is again positioned in the high intensity magnetic field afforded by the construct geometry. 
     Now, additionally referring to  FIG. 14 , there is illustrated yet another embodiment of the present invention, which illustrates the use of larger and more powerful magnets  630  and  638  relative to magnets  628  and  636 . Also ferrous members  632  and  634  have beveled ends that lead to air gap  40  with voice coil  20  being positioned at the focal high intensity magnetic field zone, again having substantial symmetry in the vertical and horizontal directions. As can be seen substantially all of the magnetic field of the magnetic circuit is contained within the construct of magnet assembly  622 . 
     Now, additionally referring to  FIG. 15 , there is shown a closer view of air gap  140 . The symmetry of the flux lines, even in this magnified view, show remarkable symmetry in air gap  140 . Magnet pairs  128  and  130  as well as  136  and  138  are in a bucking configuration with similar poles facing each other. This arrangement dramatically increases the intensity of the magnetic field in air gap  140  between ferrous members  132  and  134 . In contrast to the symmetry of the flux lines in  FIG. 15 , please now refer to  FIG. 16 , where the flux lines of the construct of  FIG. 11  are shown in a closer view, where there is now less symmetry in the horizontal direction when vertically displaced from ferrous member  432 . 
     Now, additionally referring to  FIG. 17 , there is shown another geometry of the present invention for the production of an intense magnetic field in air gap  740 . This rendition also has significant symmetry in the flux lines in air gap  740 . 
     Now, additionally referring to  FIG. 18  is a single magnet prior art configuration of a magnetic assembly  50  having a magnet  52 , and ferrous pieces  54  and  56  positioned to form an air gap  58  that illustrates the asymmetrical magnetic flux lines of the prior art construct of a magnetic assembly  50 . 
     Now, additionally referring to  FIG. 19  there is shown another embodiment of the present invention having three magnets  830 ,  836  and  838 . Again, this is a cross-sectional view of one part of a ring magnetic assembly  822 . Here the magnetic field emanating from the S pole of magnet  830  is magnetically proximate to the magnetic zone present in ferrous member  834 . 
     Now, additionally referring to  FIG. 20  there is shown still yet another embodiment of the present invention having differing sizes of magnets  928 ,  930 ,  936  and  938 , each also having differing magnetic strengths. Additionally, ferrous members  932  and  934  are shaped in an upward fashion to show the associated pathway of magnetic flux lines and the creation of an intense magnetic field in air gap  940 . 
     Now, additionally referring to  FIG. 21 , there is shown a magnetic assembly  1022  (again in cross-section as a part of a ring magnetic assembly  1022  having magnets  1028 ,  1030 ,  1036 ,  1038 ,  1042  and  1044 , and ferrous members  1032 ,  1034 ,  1046  and  1048  positioned between pairs of the magnets. 
     Generally the magnets are ring magnets with one set radially outward from the inner set. The magnetic pole orientations are in a bucking orientation so that the surrounding ferrous members  24 ,  26 A and  26 B not only provide a path for the magnetic lines to congregate, but also provide physical strength to hold magnetic assemblies  22  together. As can be seen in the figures the magnets generally are ring magnets having a common axis and several are positioned radially apart while the magnets that are axially spaced are in a magnetic bucking orientation. Also, pairs of radially separated magnets are concentrically located. It is also contemplated that the geometry of the magnetic assembly may have the radially apart magnets have their poles aligned in a bucking configuration and that magnetic zones be formed therebetween with an air gap being provided in either a radially inward manner or a radially outward manner. 
     While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Technology Classification (CPC): 7