PATENT DOCUMENT

Publication Number: US-9277323-B2
Application Number: US-201414225210-A
Country: US
Kind Code: B2

Title: Compact audio speaker

Abstract:
A audio speaker includes two parallel magnetically permeable plates and a diaphragm movably supported parallel to and approximately equidistant from the plates by a surround. A magnet assembly is coupled to the two magnetically permeable plates and passes through an opening in the diaphragm. The magnet assembly includes two magnets that are coupled with two like poles adjacent the diaphragm. A voice coil is coupled around the opening in the diaphragm to move the diaphragm when an electrical current flows in the voice coil. A suspension ring may surround a portion of the magnet assembly with a first end sealed to the diaphragm and an opposing second end sealed to one of the two plates to separate a back volume from a front volume. Some embodiments include several magnetic assemblies passing through the diaphragm with a voice coil and a suspension ring for each magnet assembly.

Claims:
What is claimed is: 
     
       1. An audio speaker, comprising:
 two magnetically permeable plates in a parallel, spaced apart relationship; 
 a diaphragm supported between the two magnetically permeable plates to define a front volume on a first side of the diaphragm and a back volume on a second side of the diaphragm opposite the first side; 
 a first magnet assembly coupled to the two magnetically permeable plates and passing through a first opening in the diaphragm, the first magnet assembly including two magnets that are coupled with two like poles adjacent the diaphragm; 
 a pleated first suspension ring that surrounds a portion of the first magnet assembly with a first end sealed to the diaphragm and an opposing second end sealed to one of the two magnetically permeable plates to separate the back volume from the front volume; and 
 a first voice coil coupled to the diaphragm and surrounding the first opening in the diaphragm through which the first magnet assembly passes. 
 
     
     
       2. The audio speaker of  claim 1  further comprising:
 a second magnet assembly coupled to the two magnetically permeable plates and passing through a second opening in the diaphragm, the second magnet assembly including two magnets that are coupled with the two like poles adjacent the two magnetically permeable plates; and 
 a second voice coil coupled to the diaphragm and surrounding the second opening in the diaphragm. 
 
     
     
       3. The audio speaker of  claim 1  further comprising:
 second and third magnet assemblies coupled to the two magnetically permeable plates and passing through second and third openings in the diaphragm such that the first magnet assembly is between the second and third magnet assemblies, the second and third magnet assemblies each including two magnets that are coupled with the two like poles adjacent the two magnetically permeable plates; and 
 second and third voice coils coupled to the diaphragm and surrounding the second and third openings in the diaphragm through which the second and third magnet assemblies pass. 
 
     
     
       4. The audio speaker of  claim 1  wherein the front volume is vented to atmosphere. 
     
     
       5. The audio speaker of  claim 1  further comprising two frame members that support the two magnetically permeable plates and capture a periphery of the diaphragm between the two frame members. 
     
     
       6. The audio speaker of  claim 5  wherein the front volume is vented to atmosphere through a third opening in one of the two frame members. 
     
     
       7. The audio speaker of  claim 6  wherein the audio speaker is in a housing and the third opening is coupled to a port in a wall of the housing. 
     
     
       8. The audio speaker of  claim 7  wherein the back volume is vented to a closed volume in the housing. 
     
     
       9. A device comprising:
 a housing; and 
 an audio speaker enclosed in the housing, the audio speaker including
 two magnetically permeable plates in a parallel, spaced apart relationship, 
 a diaphragm supported between the two magnetically permeable plates to define a front volume on a first side of the diaphragm and a back volume on a second side of the diaphragm opposite the first side, 
 a magnet assembly coupled to the two magnetically permeable plates and passing through an opening in the diaphragm, the magnet assembly including two magnets that are coupled with two like poles adjacent the diaphragm, 
 a voice coil coupled to the diaphragm and surrounding the opening in the diaphragm through which the magnet assembly passes, and 
 a suspension ring that surrounds a portion of the magnet assembly with a first end sealed to the diaphragm and an opposing second end sealed to one of the two magnetically permeable plates to separate the back volume from the front volume. 
 
 
     
     
       10. The device of  claim 9  wherein the front volume of the audio speaker is vented to atmosphere through a port in a wall of the housing. 
     
     
       11. The device of  claim 9  wherein the audio speaker further comprises two frame members that support the two magnetically permeable plates and capture a periphery of the diaphragm between the two frame members. 
     
     
       12. The device of  claim 11  wherein the front volume of the audio speaker is vented to atmosphere through a first opening in one of the two frame members that is sealed to a port in a wall of the housing. 
     
     
       13. The device of  claim 12  wherein the back volume of the audio speaker is vented to a closed volume in the housing. 
     
     
       14. The device of  claim 9  wherein the suspension ring of the audio speaker is pleated. 
     
     
       15. The device of  claim 9  wherein the diaphragm includes a surround that movably supports a center portion of the diaphragm. 
     
     
       16. An audio speaker, comprising:
 two magnetically permeable plates in a parallel, spaced apart relationship; 
 a diaphragm; 
 means for movably supporting the diaphragm between the two magnetically permeable plates to define a front volume on a first side of the diaphragm and a back volume on a second side of the diaphragm opposite the first side; 
 a magnet assembly coupled to the two magnetically permeable plates and passing through an opening in the diaphragm, the magnet assembly including two magnets that are coupled with two like poles adjacent the diaphragm; 
 a voice coil coupled to the diaphragm and surrounding the opening in the diaphragm through which the magnet assembly passes; and 
 means for separating the back volume from the front volume. 
 
     
     
       17. The audio speaker of  claim 16  wherein the front volume is vented to atmosphere. 
     
     
       18. The audio speaker of  claim 16  further comprising two frame members that support the two magnetically permeable plates and capture a periphery of the diaphragm between the two frame members. 
     
     
       19. The audio speaker of  claim 18  wherein the front volume is vented to atmosphere through a first opening in one of the two frame members. 
     
     
       20. The audio speaker of  claim 19  wherein the audio speaker is in a housing and the opening in one of the two frame members is coupled to a port in a wall of the housing. 
     
     
       21. The audio speaker of  claim 20  wherein the back volume is vented to a closed volume in the housing.

Description:
BACKGROUND 
     1. Field 
     Embodiments of the invention relate to the field of electromagnetic audio speakers; and more specifically, to audio speakers having permanent magnets with like poles juxtaposed. 
     2. Background 
     Audio speakers use electrical signals to produce air pressure waves which are perceived as sounds. Many audio speakers use a diaphragm that is movably suspended in a frame. The diaphragm is coupled to a voice coil that is suspended in a magnetic field. The electrical signals representing the sound flow through the voice coil and interact with the magnetic field. This causes the voice coil and the coupled diaphragm to oscillate in response to the electrical signal. The oscillation of the diaphragm produces air pressure waves. 
     It is desirable for the audio speaker to displace a large volume of air relative to the volume of the audio speaker because the volume of air displaced determines the volume of the sound produced. Many audio speakers are used in compact devices such as personal music players and cellular telephones. 
     It would be desirable to provide an audio speaker that is compact in size with a form factor that is suitable for use in compact portable personal devices that can deliver a substantial volume of sound. 
     SUMMARY 
     A audio speaker includes two parallel magnetically permeable plates and a diaphragm movably supported parallel to and approximately equidistant from the plates by a surround. A magnet assembly is coupled to the two magnetically permeable plates and passes through an opening in the diaphragm. The magnet assembly includes two magnets that are coupled with two like poles adjacent the diaphragm. A voice coil is coupled around the opening in the diaphragm to move the diaphragm when an electrical current flows in the voice coil. A suspension ring may surround a portion of the magnet assembly with a first end sealed to the diaphragm and an opposing second end sealed to one of the two plates to separate a back volume from a front volume. Some embodiments include several magnetic assemblies passing through the diaphragm with a voice coil and a suspension ring for each magnet assembly. 
     Other features and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention by way of example and not limitation. In the drawings, in which like reference numerals indicate similar elements: 
         FIG. 1  is a pictorial view of an audio speaker. 
         FIG. 2  is a pictorial view of the audio speaker of  FIG. 1  with a top piece removed. 
         FIG. 3  is a pictorial view of the audio speaker of  FIG. 2  with additional pieces removed. 
         FIG. 4  is an exploded view of the audio speaker of  FIG. 1 . 
         FIG. 5  is a cross-section view of the audio speaker of  FIG. 1 . 
         FIG. 6  is a pictorial view of a device that includes the audio speaker of  FIG. 1  shown by hidden lines. 
         FIG. 7  is a pictorial view of another audio speaker with the top portion removed. 
         FIG. 8  is a pictorial view of yet another audio speaker with the top portion removed. 
         FIG. 9  is a cross-section view of another audio speaker. 
         FIG. 10  is a cross-section view of yet another audio speaker. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. 
       FIGS. 1 through 5  show an audio speaker  100  that embodies the invention. As shown in  FIG. 1 , the audio speaker  100  may be provided in the form of a thin rectangular package that is suitable for use in compact portable personal devices. Profiles other than the rectangular profile shown may also be used. 
     The audio speaker  100  includes two magnetically permeable plates  102 ,  104 . The two plates  102 ,  104  are supported by frame members  106 ,  108  in a parallel, spaced apart relationship. 
     A diaphragm  110  is supported by the frame members  106 ,  108  parallel to and approximately equidistant from the two magnetically permeable plates  102 ,  104 . The frame members  106 ,  108  may also be magnetically permeable. 
       FIG. 2  shows the audio speaker  100  with the upper magnetically permeable plate  102  removed so that the diaphragm  110  is visible. A portion of the diaphragm  110  is a flexible surround  210  that allows the center portion of the diaphragm to move freely between the plates. The flexible surround  210  is an exemplary means for movably supporting the diaphragm and other means may be used to support the diaphragm with low resistance to movement. The outer periphery of the diaphragm  110  may be captured between the frame members  106 ,  108 . The diaphragm  110  defines a front volume on a first side of the diaphragm and a back volume on a second side of the diaphragm opposite the first side. 
       FIG. 4  shows an exploded view of the audio speaker  100 . A magnet assembly is coupled to the two magnetically permeable plates  102 ,  104 . The magnet assembly includes two magnets  200 ,  300 . The magnets pass through an opening  402  in the diaphragm. 
       FIG. 5  shows an cross-section view of the audio speaker  100 . The two magnets  200 ,  300  of the magnet assembly are coupled with two like poles  206 ,  306  adjacent the diaphragm  110 . For example, the positive magnetic poles of the two magnets  200 ,  300  may be juxtaposed and the negative magnetic poles may be adjacent the two magnetically permeable plates  102 ,  104 . 
     It will be appreciated that the two magnets  200 ,  300  will repel one another. The plates  102 ,  104  provide a clamping force to keep the two magnets is contact with each other. The plates  102 ,  104 , the frame members  106 ,  108 , and the two magnets  200 ,  300  provide a closed magnetic circuit. 
     As seen in  FIGS. 2 and 4 , a voice coil  212  is coupled to the diaphragm  110  surrounding the opening  402  in the diaphragm through which the magnet assembly passes. The voice coil  212  causes the diaphragm  110  to move between the plates  102 ,  104  when an electrical current flows in the voice coil. Leads  112 ,  114  extend from the voice coil  212  to the outside of the frame members  106 ,  108  for connection to a circuit that provides the electrical current to actuate the diaphragm. 
     A first opening  116  may be provided in the frame member  106  that surrounds the front volume. The first opening  116  provides an egress for the sound pressure waves created in the front volume by movement of the diaphragm  110 . The first opening may be provided in other ways, such as by one or more openings in the magnetically permeable plate  102 . 
       FIG. 6  shows the audio speaker  100  mounted in a device having a housing  600 . If the audio speaker  100  is in a housing  600 , the first opening  116  may provide a vent from the front volume to atmosphere that is coupled to a port  616  in a wall of the housing. 
       FIG. 3  shows the audio speaker  100  with the diaphragm  110  removed so that the back volume is visible. It will be appreciated that leakage of air between the front volume and the back volume through the opening  402  in the diaphragm  110  through which the magnet assembly passes reduces the efficiency of the audio speaker  100 . To reduce the leakage between the front volume and the back volume, a suspension ring  302  may be provided surrounding the lower magnet  300 . A first end of the suspension ring  302  is sealed to the diaphragm  110  surrounding the opening  402  in the diaphragm. An opposing second end of the suspension ring  302  is sealed to the lower plate  104 . Thus the suspension ring  302  separates the back volume from the front volume and reduces leakage between them. 
     A second opening  316  may be provided in the frame member  108  that surrounds the back volume. The second opening  316  provides an egress for the sound pressure waves created in the back volume by movement of the diaphragm  110 . The opening may be provided in other ways, such as by one or more openings in the magnetically permeable plate  102 . It will be appreciated that the sound pressure waves in the back volume are out of phase with the sound pressure waves in the front volume. If a second opening  316  is provided to the back volume, the second opening may vent the second side of the diaphragm to a closed volume in the housing  600  of the device in which the audio speaker  100  is mounted. The closed volume is sealed with respect to atmosphere. This arrangement prevents the sound pressure waves from the back volume from mixing with the sound pressure waves from the front volume. 
     In  FIG. 6  the location of the second opening  316  is indicated although the second opening has been treated as being on a hidden side of the audio speaker  100  for clarity of the figure. In the embodiment shown in  FIG. 6 , the connection between the first opening  116  in the speaker and the port  616  in the wall of the housing is sealed so that the entire internal volume of the housing  600  is sealed with respect to atmosphere to provide the closed volume. In other embodiments, the closed volume is a portion of the interior of the housing and the connection between the second opening  316  in the speaker and the closed volume is sealed with respect to atmosphere. 
       FIG. 7  shows another embodiment of an audio speaker  700 . In this embodiment, the suspension ring  702  is pleated. This may reduce the amount of force the suspension ring  702  exerts on the diaphragm as it moves. 
       FIG. 8  shows another embodiment of an audio speaker  800 . In this embodiment, a diaphragm  810  is supported between two frame members  806 ,  808 . A second magnet assembly  820  and a third magnet assembly  860  are coupled to two magnetically permeable plates  804  (the upper is not shown for clarity) that are supported by the two frame members  806 ,  808 . The second and third magnet assemblies  820 ,  860  are located such that the first magnet assembly  840  is between them. For the purposes of this description between is used to mean that the distance between the first magnet assembly and either the second or the third magnet assembly is less than the distance between the second and the third magnet assemblies. 
     In the embodiment of an audio speaker shown in  FIG. 8 , the first, second and third magnet assemblies  840 ,  820 ,  860  all lie on a straight line. In other embodiments this may not be the case. It will be appreciated that, for the purposes of this description, a first magnet assembly located at the vertex of a rectangle is between two magnet assemblies located at the adjacent vertices. For example, the magnet assembly identified by reference numeral  870  lies between the magnet assemblies identified by reference numerals  850  and  860 . 
     The second and third magnet assemblies  820 ,  860  each include two magnets. The second and third magnet assemblies are coupled to two magnetically permeable plates with the two like poles adjacent the two magnetically permeable plates. Thus, the first magnet assembly has an opposite “polarity” from the second and third magnet assemblies with the two like poles of the first magnet assembly adjacent the diaphragm. As suggested by the symbols shown on the upper surfaces of the magnet assemblies, the first magnet assembly  840  is shown with the negative magnetic poles adjacent the two magnetically permeable plates. The second and third magnet assemblies  820 ,  860  are shown with the positive magnetic poles adjacent the two magnetically permeable plates. 
     The second and third magnet assemblies  820 ,  860  each pass through an additional opening in the diaphragm  810 . Second and third voice coils  822 ,  862  are coupled to the diaphragm  810  and surround these additional second and third openings in the diaphragm through which the second and third magnet assemblies pass. While three magnet assemblies have been described for clarity, the embodiment shown includes six magnet assemblies  820 ,  830 ,  840 ,  850 ,  860   870 . It will be appreciated that any three adjacent magnet assemblies of the six are arranged as described since the magnetic polarity is reversed between all adjacent magnet assemblies. 
     Other embodiments may use other numbers of magnet assemblies. This necessitates one opening in the diaphragm for each magnet assembly. A voice coil will surround each opening and interact with the magnet assembly that passes through the opening and surrounding voice coil. Using multiple magnet assemblies may allow the diaphragm to be moved with a motion that displaces a greater volume of air in proportion to the overall volume of the audio speaker. 
       FIG. 9  is a cross-section view of another audio speaker. The embodiment shown provides three magnet assemblies having upper magnets  920 ,  940 ,  960 . It will be appreciated that this cross-section is similar to the three magnet assemblies found along the long edges of the embodiment shown in  FIG. 8 . 
     As previously discussed, each magnet assembly includes two permanent magnets having the ends with the same magnetic polarity adjacent one another. In the embodiment shown, two permanent magnets  940 ,  950  form a first magnet assembly. The ends  944 ,  954  having a positive magnetic polarity are adjacent the diaphragm  910 . Two additional magnets  920 ,  930  form a second magnet assembly. Another two magnets  960 ,  970  form a third magnet assembly. The first magnet assembly is between the second and third magnet assemblies. The second and third magnet assemblies are coupled to the two magnetically permeable plates  902 ,  904  with the ends  924 ,  934 ,  964 ,  974  of the magnets  920 ,  930 ,  960 ,  970  having a positive magnetic polarity adjacent the two magnetically permeable plates. Thus the adjacent pairs of magnetic assemblies are arranged with opposite magnet polarities. 
     Each of the magnetic assemblies passes through its own opening in the diaphragm  910 . Each opening is spaced apart from the other openings in the diaphragm. A voice coil  922 ,  942 ,  962  surrounds each opening in the diaphragm  910  to interact with the one of the magnetic assemblies that passes through the voice coil. 
     A suspension ring  938 ,  958 ,  978  may be provided for each opening in the diaphragm  910 . The suspension rings  938 ,  958 ,  978  may be distributed with some suspension rings sealed to the back side of the diaphragm  910  and the lower magnetically permeable plate  904  and other suspension rings sealed to the front side of the diaphragm and the upper magnetically permeable plate  902 . Arranging the suspension rings  938 ,  958 ,  978  on both sides of the diaphragm  910  may provide a better distribution of the forces exerted by the suspension rings. 
       FIG. 10  is a cross-section view of yet another audio speaker. The embodiment shown provides two magnet assemblies having upper magnets  1020 ,  1040 . It will be appreciated that this cross-section is similar to the three pairs of magnet assemblies found across the short dimension of the embodiment shown in  FIG. 8 . 
     The two magnetic assemblies are arranged with opposite magnet polarities. Two permanent magnets  1020 ,  1030  form a first magnet assembly. The ends  1024 ,  1034  having a positive magnetic polarity are adjacent the diaphragm  1010 . Another two magnets  1040 ,  1050  form a second magnet assembly. The ends  1044 ,  1054  having a positive magnetic polarity are coupled to the two magnetically permeable plates  1002 ,  1004 . The structure of this embodiment is otherwise similar to the previously described embodiments. 
     While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention is not limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those of ordinary skill in the art. The description is thus to be regarded as illustrative instead of limiting.

Metadata:
Filing Date: 20140325
Publication Date: 20160301
Grant Date: 20160301
Priority Date: 20140325
Inventors: LOCKE ANTONY J.
PORTER SCOTT P.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04R1/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R7/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/28", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R1/28", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R7/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R7/04", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R1/00", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 54192302