PATENT DOCUMENT

Publication Number: US-9900698-B2
Application Number: US-201514788205-A
Country: US
Kind Code: B2

Title: Graphene composite acoustic diaphragm

Abstract:
The disclosure relates to an audio device that includes a diaphragm having a graphene material, such as a graphene flake, that is incorporated into a base material. The audio device may form part of a speaker device, a microphone device, or a headphone device. The concentration of the graphene and/or a size of the graphene flakes may be varied throughout the diaphragm to define a stiff center portion and a flexible portion that surrounds the center portion.

Claims:
What is claimed is: 
     
       1. An audio device comprising:
 a support structure; 
 an acoustic element disposed within a recess of the support structure; and 
 a diaphragm coupled to the support structure, the diaphragm comprising:
 a center portion comprising a base material; 
 a flexible portion comprising the base material and surrounding the center portion and configured to flex in response to a movement of the center portion with respect to the support structure; and 
 a graphene flake material molded into the base material, wherein a concentration of the graphene flake material is higher within the center portion than within the flexible portion such that an elastic modulus of the center portion is greater than an elastic modulus of the flexible portion. 
 
 
     
     
       2. The audio device of  claim 1 , wherein:
 the center portion has a first stiffness; 
 the flexible portion has a second stiffness; and 
 the first stiffness is greater than the second stiffness. 
 
     
     
       3. The audio device of  claim 1 , wherein:
 the center portion includes a first size of graphene flake; 
 the flexible portion includes a second size of graphene flake; and the first size is greater than the second size. 
 
     
     
       4. The audio device of  claim 1 , wherein the diaphragm comprises:
 a membrane structure, at least a portion of which forms the flexible portion; and 
 a composite cap structure bonded to a surface of the membrane structure and forming at least a portion of the center portion. 
 
     
     
       5. The audio device of  claim 1 , wherein:
 the base material comprises a polymer; and 
 the graphene flake material is molded into the polymer. 
 
     
     
       6. The audio device of  claim 1 , wherein:
 the acoustic element comprises: 
 a magnet disposed within the recess of the support structure; and a voice coil attached to the center portion of the diaphragm and 
 electromagnetically coupled to the magnet; and 
 the flexible portion is configured to flex in response to relative motion between the magnet and the voice coil. 
 
     
     
       7. The audio device of  claim 1 , wherein the audio device forms at least one of a speaker, a headphone, and a microphone. 
     
     
       8. A portable electronic device comprising:
 a housing defining an opening; 
 a display positioned in the opening of the housing; 
 an audio device comprising:
 a support structure; 
 a diaphragm flexibly connected to the support structure and configured to transmit or receive sound waves, wherein the diaphragm includes graphene molded into a base material, and wherein a concentration of the graphene is higher within a center portion of the diaphragm than within a flexible portion of the diaphragm such that an elastic modulus of the center portion is greater than an elastic modulus of the flexible portion. 
 
 
     
     
       9. The portable electronic device according to  claim 8 , wherein:
 the center portion comprises: 
 an inner center portion; and 
 an outer center portion surrounding the inner center portion, wherein: 
 the outer center portion has a graphene concentration that is lower than a graphene concentration of the inner center portion; and 
 the flexible portion has a graphene concentration that is lower than the graphene concentration of the outer center portion. 
 
     
     
       10. The portable electronic device according to  claim 9 , wherein the flexible portion has a substantially zero graphene concentration. 
     
     
       11. The portable electronic device according to  claim 8 , wherein:
 the diaphragm forms a conically shaped dome structure; 
 the conically shaped dome structure defines an edge portion surrounding the flexible portion; and 
 the edge portion is attached to the support structure. 
 
     
     
       12. The portable electronic device according to  claim 11 , wherein a graphene concentration of the edge portion is greater than the graphene concentration of the flexible portion. 
     
     
       13. The portable electronic device according to  claim 8 , wherein:
 the base material is a polymer; and 
 the graphene is a graphene flake material. 
 
     
     
       14. A method for manufacturing a diaphragm for an audio device, the method comprising:
 forming a support structure; 
 positioning an acoustic element within a recess of the support structure; 
 forming a diaphragm and coupling it to the support structure, wherein the diaphragm is formed by:
 preparing a base material; 
 forming a flexible portion that surrounds a center portion, wherein the flexible portion and the center portion are both formed from the base material; 
 molding graphene flakes within the base material, wherein a concentration of the graphene flakes is higher within the center portion than within the flexible portion such that an elastic modulus of the center portion is greater than an elastic modulus of the flexible portion. 
 
 
     
     
       15. The method of  claim 14 , wherein:
 molding the graphene flakes within the base material includes varying a concentration of the graphene flakes; and 
 forming the diaphragm comprises forming a first and second distinct portion of the diaphragm, each having a different concentration of graphene flakes. 
 
     
     
       16. The method of  claim 15 , wherein:
 the first distinct portion defines the center portion formed from a first composite mixture having a first concentration of graphene flakes; 
 the second distinct portion defines the flexible portion that surrounds the center portion and is formed from a second composite mixture having a second concentration of graphene flakes; and 
 the first concentration is greater than the second concentration. 
 
     
     
       17. The method of  claim 14 , wherein:
 preparing the base material comprises forming a first composite mixture having a first size of graphene flakes; 
 and the method further comprises:
 adding a second size of graphene flakes to the base material to create a second composite mixture, the first size being greater than the second size; 
 molding the center portion of the diaphragm using the first composite mixture; and 
 molding the flexible portion of the diaphragm surrounding the center portion using the second composite mixture. 
 
 
     
     
       18. The method of  claim 14 , wherein forming the diaphragm further comprises:
 forming an inner center portion of the center portion, wherein the inner center portion has a first concentration of graphene flakes; 
 forming an outer center portion of the center portion, wherein the outer center portion has a second concentration of graphene flakes that is lower than the first concentration; and 
 forming the flexible portion having a third concentration of graphene flakes that is lower than the second concentration. 
 
     
     
       19. The method of  claim 14 , wherein the base material comprises a polymer and the molding is performed with an injection molding process.

Description:
FIELD 
     Embodiments described herein generally relate to the field of acoustic systems and, more specifically, to an acoustic device that includes a diaphragm having one or more portions formed using graphene. 
     BACKGROUND 
     Audio functionality is an important aspect of various electronic devices. For example, laptop computers, tablets, mobile telephones, and the like may all include some type of acoustic speaker and/or microphone to transmit and/or receive audio signals. As devices become smaller and lighter, it becomes more difficult to provide high-quality audio devices using conventional materials. In particular, it may be challenging to produce an audio device that is compact and lightweight while also providing a desired audio performance. 
     SUMMARY 
     Embodiments described herein may relate to, include, or take the form of acoustic devices having a diaphragm that incorporates a graphene material, such as graphene flakes. In some embodiments, a polymer composite may include graphene flakes and form at least a portion of a diaphragm. The polymer composite may be used to make the diaphragm thinner, stiffer, and/or lighter. 
     Some example embodiments are directed to an audio device including a support structure and an acoustic element that is disposed within a recess of the support structure. The audio device also includes a diaphragm that is coupled to the support structure. The diaphragm may include a center portion formed from a base material and a graphene flake material that is incorporated into the base material. The diaphragm also includes a flexible portion that surrounds the center portion. The flexible portion may be coupled to the support structure and may be configured to flex in response to a movement of the center portion with respect to the support structure or acoustic element. In some embodiments, the base material comprises a polymer and the graphene flake material is molded into the polymer material. 
     In some embodiments, the center portion has a first stiffness that is greater than a second stiffness of the flexible portion. The center portion may include a first concentration of graphene flakes and the flexible portion may include a second concentration of graphene flakes. The first concentration may be greater than the second concentration. In some embodiments, the center portion includes a first size of graphene flake and the flexible portion includes a second size of graphene flake. The first size may be greater than the second size resulting in a stiffer center portion. 
     In some embodiments, the center portion includes a membrane structure and a composite cap structure that is bonded to a surface of the membrane structure. A portion of the membrane structure may form the flexible portion of the diaphragm. The diaphragm may form a conical dome shape or other similar contoured shape. 
     In some embodiments, the audio element includes a magnet that is disposed within the recess of the support structure. A voice coil may be attached to the center portion of the diaphragm and may be electromagnetically coupled to the magnet. The flexible portion may be configured to flex in response to relative motion between the magnet and the voice coil. The audio device may form a speaker, a headphone, a microphone, or other similar device. 
     Some example embodiments are directed to a portable electronic device that includes a housing that defines an opening. A display may be positioned in the opening of the housing. A processor may be coupled to the display and an audio device. The audio device may include a support structure and a diaphragm that is flexibly connected to the support structure. The diaphragm may be formed from graphene that is incorporated into a base material. The concentration of the graphene may vary within the diaphragm to define a center portion and a flexible portion such that the center portion is stiffer than the flexible portion. The diaphragm may be configured to transmit and/or receive sound waves. 
     In some embodiments, the center portion includes an inner center portion and an outer center portion that surrounds the inner center portion. The outer center portion may have a graphene concentration that is lower than a graphene concentration of the inner center portion. The flexible portion may include a graphene concentration that is lower than the graphene concentration of the outer center portion. 
     The diaphragm may form a conically shaped dome structure. The conically shaped dome structure may define an edge portion surrounding the flexible portion in a location where the edge portion is attached to the support structure. In some embodiments, a graphene concentration of the edge portion is greater than the graphene concentration of the flexible portion. 
     Some example embodiments are directed to a method for manufacturing a diaphragm for an audio device. The method may include preparing a base material and adding graphene flakes to the base material to create a composite mixture. The method may also include forming a diaphragm by molding the composite mixture. In some cases, the diaphragm is installed in an acoustic device. In some embodiments, adding the graphene flakes includes varying the concentration of the graphene flakes to form two or more distinct portions of the diaphragm. In some cases, the base material comprises a polymer and the molding process includes an injection molding process. 
     The diaphragm may include a dome structure. A first concentration of graphene flakes may be increased in a center portion of the dome structure as compared to a second concentration of graphene flakes in a flexible portion surrounding the center portion. 
     In some embodiments, the composite mixture is a first composite mixture having a first concentration and/or first size of graphene flakes. Graphene flakes may be added to the base material to create a second composite mixture having a second concentration and/or size of graphene flakes. The first concentration may be greater than the second concentration and/or the first size graphene flake may be greater than the second size of graphene flake. A center portion of the diaphragm may be molded using the first composite mixture. A flexible portion of the diaphragm surrounding the center portion may be molded using the second composite mixture. 
     Forming the diaphragm may further comprise forming an inner center portion having a first concentration of graphene flakes and forming an outer center portion having a second concentration of graphene flakes that is lower than the first concentration. A flexible portion may also be formed having a third concentration of graphene flakes that is lower than the second concentration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  depicts an example electronic device including an audio device; 
         FIG. 2  is a cross-sectional view of a speaker device taken along section A-A; 
         FIG. 3  is a cross-sectional view of a microphone device taken along section B-B; 
         FIG. 4  is a cross-sectional view of an embodiments of a diaphragm taken along section A-A; 
         FIG. 5  is a cross-sectional view of another embodiment of a diaphragm taken along section A-A; 
         FIG. 6  is a process flow diagram of a process for making a diaphragm including graphene; and 
         FIG. 7  is an illustrative block diagram of an electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The following disclosure relates to a diaphragm formed from a composite graphene material. In general, the physical characteristics of a diaphragm may affect the performance of an audio device, such as a speaker or microphone. In particular, the acoustic performance of a speaker may depend, at least in part, on the geometry and/or structural properties of the diaphragm. In general, a speaker may include an audio element, such as a transducer (e.g., voice coil), that converts an electrical signal into movement of a diaphragm. Movement of the diaphragm may produce a pressure differential that forms sound waves or other acoustic response. The performance of the speaker may be quantified by the degree of correlation between the electrical signal provided to the speaker and the mechanical response of the transducer and diaphragm. 
     The correlation between an electrical input and the mechanical output of a speaker may not be perfect due to practical limitations of the hardware. Variability in the correlation between the electrical signal and the mechanical or acoustic response may sometimes be referred to as distortion. In general, a diaphragm having a high stiffness and light weight may allow a speaker transducer to react more quickly, which may minimize or reduce distortion of the electrical signal. Therefore, it may be advantageous to use a material that has a high strength to weight ratio. 
     Achieving low distortion in small audio devices is particularly challenging. Using some traditional materials, the mass of the diaphragm may be too high for a small or compact transducer, which may result in unacceptable levels of distortion. In some cases, the distortion may be reduced by using a mechanical damper. However, mechanical dampers may increase the complexity and cost as well as reduce the power efficiency of the audio device. 
     The embodiments described herein are directed to acoustic devices having a diaphragm incorporating a graphene or graphene flake material, which may increase the stiffness of the diaphragm without significantly increasing the weight. The graphene may be included in a graphene-flake composite polymer material that is molded or otherwise formed into the diaphragm component. The composite polymer may be used to make the diaphragm thinner, stiffer, and/or lighter, as compared to some traditional diaphragm materials. In some embodiments, a graphene composite polymer may be used to create smaller acoustic devices without significantly compromising audio quality. 
     In some implementations, using a graphene flake material may improve the mechanical response of the audio device. In particular, a diaphragm formed from a graphene or graphene flake material may be configured to have a mass and spring constant that is tuned to provide a particular mechanical or acoustic response. In some cases, the use of graphene or graphene flake material may reduce or eliminate the need for additional external damping. Graphene may be used to produce a light diaphragm with a low spring constant (e.g., stiffer), which may eliminate the need for a separate damping mechanism, which may reduce complexity of the audio device. A reduction in dampening may also improve the efficiency and reduce the power consumption of the audio device. 
     In some embodiments described herein, the concentration of the graphene may be varied throughout the diaphragm to provide a structure having particular mechanical properties. In particular, a higher concentration of graphene may be used in a center portion of the diaphragm to increase stiffness and possibly reduce the weight of the moving mass. A lower concentration of graphene may be used in a flexible portion or other portion to increase the flexibility of select regions of the diaphragm. 
     In some embodiments described herein, the graphene includes a graphene flake that may be configured to provide particular mechanical properties. In some cases, the size of the graphene flake may be varied throughout the diaphragm to provide a structure having the desired stiffness or flexibility. In some implementations, the center portion may include a first size of graphene flake that is larger than a second size of graphene flake in the flexible portion. An increased size of the graphene flake may result in a stiffer center portion as compared to the flexible portion. The graphene flakes may also be oriented or aligned along one or more directions to provide particular mechanical properties. In particular, the a flake area of the graphene flakes may be substantially aligned with an outer or inner surface of the diaphragm. 
     While the examples described herein are directed to a graphene material in the form of a graphene flake, the examples may also apply to other forms of graphene. In particular, instead of graphene flake, the embodiments described herein may use a graphene flake stack, graphene fiber, graphene sheet, graphene spheres, graphene clusters, graphene chips, graphene particles, and so on. A combination of graphene materials may also be used to form the composite graphene diaphragm. 
     Some embodiments are directed to a method for manufacturing a diaphragm for an audio device, such as a speaker or microphone device. The method may include forming two or more distinct portions of the diaphragm using different concentrations of and/or different size graphene flakes. In some embodiments, variable amounts of graphene are incorporated into a base diaphragm material to provide a diaphragm having different levels of stiffness in different regions. In some cases, the stiffness of the diaphragm can be increased without significantly changing the mass of the diaphragm, which may reduce or eliminate the need for inclusion of additional mechanical damping mechanisms or elements in the audio device. 
     These and other embodiments are discussed below with reference to  FIGS. 1-7 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
     In general, a diaphragm that includes graphene, such as a graphene flake, may be incorporated into a variety of acoustic devices including, for example, a speaker or a microphone of an electronic device.  FIG. 1  depicts an example electronic device  101  that includes both a speaker device  106  and microphone device  107  (example audio devices). As described in more detail below, the speaker device  106  and/or the microphone device  107  may include a diaphragm that includes or incorporates a graphene or graphene flake material to increase the stiffness of the diaphragm and potentially improve the performance of the corresponding audio device(s). 
     In the example depicted in  FIG. 1 , the electronic device  101  is implemented as a smartphone. Other example electronic devices may include, without limitation, a desktop computing device, a notebook computing device, a tablet computing device, a wearable electronic device, a health monitoring device, a gaming device, a remote control device, and other types of electronic and portable electronic devices. While the following description is provided with respect to audio components integrated with an electronic device, the principles of an audio component having a graphene diaphragm may also be applied to accessory devices, such as a headphones, headsets, stand-alone speakers, and so on. 
     As shown in  FIG. 1 , the electronic device includes a housing  102  that encloses and protects the internal components of the device  101 . Example internal components are described in more detail below with respect to  FIG. 7 . The housing  102  may define one or more openings for user input devices, such as the button  104  depicted in  FIG. 1 . 
     The housing  102  may also define an opening in a top surface and a display  103  may be disposed or positioned within the opening. The display  103  may be attached directly to the housing  102  or secured within the device  101  using another component. The display  103  may include a liquid crystal display (LCD), organic light emitting diode (OLED) display, electroluminescent (EL) display, or other type of display element. The display  103  may be configured to provide a visual output to the user including, for example, a graphical user interface. The display  103  may also be configured to provide visible media content including video, images, or other graphical content. In some cases, the display  103  may also incorporate a touch sensor for receiving user input. 
     As shown in  FIG. 1 , the device  101  includes a speaker device  106  for providing audio output to the user. The audio output may correspond to the visual output provided by the display  103  and/or provide audio feedback for user input devices, such as the button  104 . In some embodiments, the speaker device  106  is configured to provide the audio for a telephone call or other audible communication. A more detailed description of the speaker device  106  is provided below with respect to  FIG. 2 . 
     As shown in  FIG. 1 , the device  101  also includes a microphone device  107 . The microphone device  107  may be configured to receive audio signals or input from the user or from a source external to the device  101 . In some cases, the microphone device  107  is configured to receive audio input for a telephone call or other audible communication. A more detailed description of the microphone device  107  is provided below with respect to  FIG. 3 . 
     As previously discussed, audio devices such as speakers and microphones may include a diaphragm component or element. In some cases, it may be advantageous for the diaphragm to include or incorporate a graphene material (e.g., a graphene flake).  FIGS. 2 and 3  depict example audio devices that may use a graphene-based diaphragm. 
       FIG. 2  depicts a cross-sectional view the speaker device  106  taken along section A-A of  FIG. 1 . As described previously, the speaker device  106  may be incorporated with an electronic device (e.g., device  101  of  FIG. 1 ) and used to produce an audio output. The speaker device  106  represents an example configuration of an audio device that includes a diaphragm formed using graphene (e.g., graphene flake). While the speaker device  106  depicted in  FIG. 2  represents an illustrative example, the configuration is not intended to be limiting. 
     As shown in  FIG. 2 , the speaker device  106  includes a support structure  202 , a magnet  203 , a voice coil  204 , and a diaphragm  205 . The support structure  202  defines a recess  218 , which may include a partially enclosed portion of the support structure  202  in which an audio element  216  is positioned. An example audio element  216 , such as an electromagnetic transducer, may be formed between a magnet  203  and a voice coil  204 , which may move with respect to each other in response to an electrical signal provided to the voice coil  204 . Changes in the electromagnetic fields produced by the voice coil  204  (due to the electrical signal) may result in a motive force between the voice coil  204  and the magnet  203 . The motive force may produce the relative movement between the voice coil  204  and the magnet  203 . In some cases, the magnet  203  may be described as being electromagnetically coupled to the voice coil  204 . 
     As shown in  FIG. 2 , a support structure  202 , which may be fixed, is coupled to the magnet  203 . Thus, a motive force between the voice coil  204  and the magnet  203  results in a movement of the voice coil  204 . In the present embodiment, the diaphragm  205  is attached to the voice coil  204  such that movement of the voice coil  204  results in a movement of a center portion  209  of the diaphragm  205  with respect to the support structure  202 . Movement of diaphragm  205  may cause the diaphragm  205  to displace air and generate sound waves  208  as a result of a vibratory or oscillatory movement of the voice coil  204 . In some embodiments, the sound waves  208  may create the acoustic output or response of the speaker device  106 . As shown in  FIG. 2 , the diaphragm may include a conical dome shape that may facilitate the formation of the sound waves  208 . 
     In the embodiment of  FIG. 2 , the diaphragm  205  is coupled to the support structure  202 . In particular, the diaphragm  205  is attached to the support structure  202  at edge portion  206 . In some embodiments, the edge portion  206  is located within or adjacent to a flexible portion  207  of the diaphragm, which surrounds the center portion  209  of the diaphragm  205 . In this configuration, the edge portion  206  of the diaphragm  205  is fixed with respect to the support structure  202 . Because the center portion  209  moves in conjunction with the voice coil  204 , the center portion  209  will move with respect to the edge portion  206 , which is coupled to the fixed support structure  202 . Thus, the flexible portion  207  may be configured to provide compliance between the moving center portion  209  and the stationary edge portion  206 , and may flex in response to a movement of the voice coil  204  with respect to the magnet  203 . 
     It may be advantageous that the diaphragm have both flexible and stiff regions. In particular, the flexible portion  207  may form a flexible or compliant portion of the diaphragm  205  to accommodate the movement caused by oscillation of the voice coil  204 . Additionally, to provide a suitable acoustic response, it may be advantageous that the center portion  209  of the diaphragm  205  be relatively stiff or rigid, which may result in sound waves  208  having a consistent and/or suitable audio quality. 
     Providing a diaphragm  205  that is both stiff or substantially rigid in the center portion  209  while also flexible or compliant in the flexible portion  207  may present a significant design challenge, particularly if the mass of the diaphragm  205  is very low. One potential solution is to incorporate graphene, such as a graphene flake material  210 , into the diaphragm  205  in order increase the stiffness of the center portion  209 . In some embodiments, center portion  209  is constructed of a base material  214  and a graphene flake material  210  that is incorporated into the base material  214 . In some implementations, the base material  214  may include a polymer or other synthetic material. 
     The diaphragm  205  may include varying amounts of graphene in different regions or portions to provide both a rigid center portion  209  and a flexible portion  207 . In some implementations, the concentration of graphene flake material in the center portion  209  is greater than the concentration of graphene flake material in the flexible portion  207 . The greater concentration of graphene flake material may result in the center portion  209  having a stiffness that is greater than the flexible portion  207 . In some embodiments, the flexible portion  207  has no graphene flakes or a substantially zero graphene flake concentration. Example diaphragms having varying concentrations of graphene flakes are described below with respect to  FIGS. 4 and 5 . 
     The diaphragm  205  may also have variations in graphene flake size. For example, the center portion  209  may include a first size of graphene flake and the flexible portion  207  may include a second size of graphene flake that is smaller than the first size. The decreased size of the graphene flake may result in a more flexible or pliable flexible portion  207  as compared to the center portion  209 . Conversely, the increased size of the graphene flake may result in a stiffer center portion  209  as compared to the flexible portion  207 . 
     While varying concentration and/or size of graphene flakes may be used to vary the stiffness of the diaphragm  205 , graphene flakes may also be added in improve the water resistance of the diaphragm  205 . In general, graphene flakes may be substantially impermeable to water and may function as a moisture barrier. Thus, graphene flakes  210  in various concentrations may be incorporated into the diaphragm  205  to reduce the water or moisture permeability of the diaphragm  205  and possibly improve the water resistance of the speaker  106 . 
     The example diaphragm  205  depicted in  FIG. 2  has a conical dome shaped structure with an outward or convex curvature. It should be understood that either a convex or a concave curvature may be used to produce the sound waves  208  and, thus, the specific shape or curvature is not critical to this embodiment. Additionally, while the example speaker device  106  of  FIG. 2  depicts the magnet  203  as stationary and the voice coil  204  as moving, alternative embodiments may be constructed in which the voice coil  204  is stationary and the magnet  203  moves. 
     As shown in  FIG. 2 , the speaker device  106  may be incorporated into an electronic device (e.g., device  101  of  FIG. 1 ). In particular, the support structure  202  may be coupled to a mounting structure  222  which attaches the speaker device  106  to the housing  102  of an electrical device. The mounting structure  222  may include multiple components or layers to facilitate mechanical coupling and/or acoustic isolation of the speaker device  106  with respect to the housing  102 . In some embodiments, the mounting structure  222  includes one or more compliant layers or gaskets to create an acoustic seal between the speaker device  106  and the housing  102 . Also, as shown in  FIG. 2 , the housing  102  may define an opening  220  or aperture through which the sound waves  208  may pass. The opening  220  may include a screen or other protective element to prevent the ingress of contaminants and protect the speaker device  106 . 
     In a similar fashion, a diaphragm that includes graphene may be used to form other types of acoustic devices, such as a microphone. In general, a microphone may function as an acoustic-to-electric transducer or sensor that converts sound in air into an electrical signal. In some microphone embodiments, sound is first converted to mechanical motion using a diaphragm. The diaphragm may be coupled to a transducer which converts the mechanical motion into an electrical signal. 
       FIG. 3  depicts a cross-sectional view of an example microphone device  107  taken along section B-B of  FIG. 1 . Similar to the speaker device of the previous example, the microphone device  107  includes a diaphragm  305  having a graphene flake material  310 . In this example, the diaphragm  305  is coupled to an audio element  316 , such as an electromagnetic transducer, that converts mechanical energy (the motion of the diaphragm  305 ) into an electrical signal. In particular, sound waves  308  may enter through the opening  320  of the housing  102  and cause the diaphragm  305  to vibrate or oscillate. The diaphragm  305  is coupled to a voice coil  304  which is electromagnetically coupled to the magnet  303 . Movement of the diaphragm  305  (caused by the sound waves  308 ) produces relative motion between the voice coil  304  and the magnet  303  resulting in an induced current in the voice coil  304 . The induced current of the voice coil  304  may form the electrical signal or output of the microphone device  107 . 
     While  FIG. 3  depicts an audio element  316  including an electromagnetic transducer with a magnet  303  and a voice coil  304 , other embodiments may use a different type of audio element  316  that is configured to convert movement into an electrical signal. For example, alternative embodiments may use a piezoelectric element that is coupled between the support structure  302  and the diaphragm  305  to produce an electrical signal in response to vibration or oscillation of the diaphragm  305 . The diaphragm  305  may form a conical dome shape that may facilitate the reception of the sound waves  308 . 
     As shown in  FIG. 3 , the magnet  303  is positioned in a recess  318  of the support structure  302  and may be attached or fixed relative to the support structure  302 . The support structure  302  is attached to the housing  102  of the electrical device by a mounting structure  322 . The mounting structure  322  may be similar to the mounting structure  222  described above with respect to  FIG. 2  and may provide both the mechanical coupling and acoustic isolation between the microphone device  107  and the housing  102 . 
     As shown in  FIG. 3 , an edge portion  306  of the diaphragm  305  is coupled or attached to the support structure  302 . Because the edge portion  306  is fixed with respect to the support structure  302  and the center portion  309  moves in response to the sound waves  308 , it may be advantageous for the flexible portion  307  to be flexible or compliant. Additionally, similar to the speaker example, it may be advantageous that the center portion  309  be rigid or stiff to improve the sensitivity of the diaphragm  305  in response to an acoustic signal, such as the sound waves  308 . Thus, similar to the speaker example, it may be advantageous to incorporate graphene, such as graphene flake material  310  into the diaphragm  305  to increase the stiffness of the center portion  309  of the diaphragm  305 . In some embodiments, center portion  309  is constructed of a base material  314  and a graphene flake material  310  that is incorporated into the base material  314 . 
     In some embodiments, the diaphragm  305  includes varying amounts of graphene in different regions or portions to provide both a rigid center portion  309  and a flexible portion  307 . In some implementations, the concentration of graphene flake material in the center portion  309  is greater than the concentration of graphene flake material in the flexible portion  307 . The greater concentration of graphene flake material may result in the center portion  309  having a stiffness that is greater than the flexible portion  307 . Similarly, a larger graphene flake may be incorporated into the center portion  309  as compared to the flexible portion  307 , which may result in a stiffer center portion  309 . The concentration and/or size of the graphene flakes  406  may also be configured to reduce the water permeability of the diaphragm  305 . Example diaphragms having varying concentrations of graphene flake material are described below with respect to  FIGS. 4 and 5 . 
       FIG. 4  depicts a cross-sectional view of an example diaphragm  405 . The example diaphragm  405  may correspond to the diaphragms  205  and  305  of  FIGS. 2 and 3 , discussed above. More generally, the diaphragm  405  may be used in a variety of acoustic devices to convert electrical signals into acoustic energy (e.g., sound waves) or, conversely, convert acoustic energy into an electrical signal. The diaphragm  405  may have a generally dome shaped geometry. 
     As shown in  FIG. 4 , the diaphragm  405  may be formed from different portions having different mechanical properties. Specifically, the diaphragm  405  includes a center portion  402  that is stiffer than the flexible portion  401  that surrounds the center portion. Additionally, the center portion  402  may include an inner center portion  403  that is surrounded by an outer center portion  404  having a different stiffness than either the inner center portion  403  and the flexible portion  401 . 
     Varying the stiffness of diaphragm  405  in areas  401 ,  403 , and  404  may be difficult to accomplish without adversely affecting the mass of diaphragm  405 , which can affect performance of the audio device. In addition, an uneven mass distribution across the diaphragm  405  may affect the vibrational response of the diaphragm  405  and adversely affect audio performance. 
     A graphene material, such as a graphene flake material, may be incorporated into the diaphragm to alter the stiffness without significantly impacting the mass. In general, graphene is pure carbon in the form of a very thin, flexible, nearly transparent sheet. In some cases, a graphene sheet may be a one atom thick sheet of graphite having carbon atoms that are densely packed in a hexagonal pattern. In some embodiments, graphene sheets may be about 0.35 nm or one atom thick. A graphene sheet may be used to form graphene flakes having a smaller area but substantially the same thickness. 
     Graphene may be up to 100 times stronger than steel by weight. Also, because graphene is a very thin material (having a thickness as low as one atom), the mass of a graphene flake can be precisely controlled by controlling the surface area or flake size. When a graphene flake is incorporated into a base material, such as a polymer, the stiffness of the composite may be precisely controlled without significantly affecting the mass. In the present example, the base material  412  may be a polymer material which may include high or low density polyethylene, polypropylene, polyvinyl chloride, polystyrene and thermoplastic polyurethanes. 
     In some cases, a graphene flake material  406  may be incorporated into a base material to adjust the stiffness across the diaphragm  405 . Embedded graphene flake material  406  may result in a diaphragm  405  that is thinner, stiffer and lighter. A light diaphragm with a low spring constant reduces the need for a complex mechanical damping mechanism and the resultant power loss due to the damping mechanisms. Varying the concentration of the graphene flake material  406  in various portions of diaphragm  405  allows the mass and stiffness of diaphragm  405  to be controlled to optimize performance. The concentration of the graphene flake may vary between concentrations as low as 0.001 percent and up to and including 2 percent. 
     With reference to the diaphragm  405  of  FIG. 4 , the center portion  402  may have a higher concentration of graphene flakes  406 , which may result in a stiffer center portion  402  without increasing the mass of diaphragm  405 . The concentration of graphene flakes  406  in the center portion  402  may be higher relative to a concentration of graphene flakes  406  at flexible portions  401  of the diaphragm  405 . The reduced graphene flake concentration in the flexible portion  401  may result in a more flexible or pliable material and facilitate vibration and movement of the diaphragm  405 . In some implementations, the flexible portion  401  may have no graphene flakes or a substantially zero concentration of graphene flakes. 
     Additionally, the center portion  402  may define two or more regions or portions that have varying levels of stiffness. In some implementations, the middle or inner portion of the center portion  402  is the most stiff and outer portions surrounding the middle of the center portion  402  may have decreasing levels of stiffness. In the embodiment depicted in  FIG. 4 , the center portion  402  includes an outer center portion  404  that surrounds an inner center portion  403 . The outer center portion  404  may have a graphene flake material concentration that is lower than the graphene flake material concentration of the inner center portion  403  resulting in a reduced stiffness. 
     The diaphragm  405  may also have variations in graphene flake size. For example, the center portion  402  may include a first size of graphene flake and the flexible portion  401  may include a second size of graphene flake that is smaller than the first size. The decreased size of the graphene flake may result in a more pliable flexible portion  401  as compared to the center portion  402 . Conversely, the increased size of the graphene flake may result in a stiffer center portion  402  as compared to the flexible portion  401 . The size of the graphene flake may vary between 1 micron in width to 500 microns in width. 
     The diaphragm  405  may also include graphene flakes or other graphene material that is oriented in one or more than one direction to provide specific mechanical properties. For example, the graphene flakes may be oriented such that a flake area of a significant portion of graphene flakes are substantially aligned with an outer surface of the diaphragm  405 . Having the graphene flakes oriented in this way may result in a diaphragm  405  that has a decreased elastic modulus in a direction perpendicular to the flake area of the graphene flakes. If the diaphragm  405  forms a conical- or dome-shaped shaped portion, as depicted in  FIG. 4 , the stiffness of the dome-shaped portion may have an increased stiffness or rigidity. Alternatively, the graphene flakes may be oriented along a different direction to provide a specific elastic modulus resulting in a desired rigidity for the diaphragm  405 . In some implementations, the orientation of the graphene flakes is substantially randomized and the composite material has an elastic modulus that is substantially isotropic. 
     While varying concentration and/or size of graphene flakes may be used to vary the stiffness of the diaphragm  405 , graphene flakes may also be added in improve the water resistance of the diaphragm  405 . In some implementations, graphene flakes  406  in various concentrations may be incorporated into the diaphragm  405  to reduce the water or moisture permeability of the diaphragm  405 . 
     In the embodiment depicted in  FIG. 4 , the diaphragm  405  is formed from a unitary structure having varying levels of graphene to define different regions or portions, each region or portion having a different stiffness. In an alternative embodiment, one or more of the regions may be formed as a separate part that is attached to the one or more other portions of the diaphragm. In some implementations, the separate portions may be bonded using an adhesive or other mechanical joining technique. In some implementations, one or more separate portions may be over-molded or insert molded onto the other portion(s) of the diaphragm. 
       FIG. 5  depicts an example diaphragm  505  formed from multiple parts. In particular, the diaphragm  505  includes a membrane structure  512  and a composite cap structure  515 . The composite cap structure  515  may be bonded or otherwise mechanically joined to a surface of the membrane structure  512 . The composite cap structure  515  may include a graphene flake material  506  incorporated into a base material  510 . Similar to the examples described above, an increased concentration of graphene flake material  506  may result in a stiffer composite cap structure  515 . The composite cap structure  515  may define all or a portion of the center portion  502  of the diaphragm. 
     As shown in  FIG. 5 , at least a portion of the membrane structure  512  forms the flexible portion  501  of the diaphragm  505 . The membrane structure  512  may be formed from a flexible material such as a polymer, rubber, or other similar material. In some implementations, the membrane structure  512  may include a lower concentration (including a zero concentration) of graphene flake material as compared to the center portion  502 , which includes the composite cap structure  515 . The composite cap structure  515  may form at least a portion of the center portion  502  of the diaphragm  505 . 
       FIG. 6  depicts a flow chart of an example process  600  for manufacturing a diaphragm for an audio device, such as a microphone or speaker. Process  600  may be used to manufacture a diaphragm similar to the diaphragms described above with respect to  FIGS. 4 and 5 . 
     In operation  601 , a polymer material is prepared. The polymer material may be a liquid, which may facilitate the addition of a graphene or graphene flake material. In some implementations, the polymer material is in an uncured liquid state. A hardener or curing agent may be added to polymer material in a subsequent operation to harden the polymer material to a solid state. In some implementations, the polymer material is a thermoplastic polymer that is heated to a liquid or molten state. The polymer material may include a polyurethane, elastomer, fluoropolymer, synthetic rubber, or other similar material. 
     In operation  602 , graphene flakes are added to the base material to create a composite mixture. The graphene flakes may be homogeneously mixed into the polymer, they may be added to the surface of the polymer as a coating, or otherwise integrated with the polymer material. In some implementations, graphene flakes are added to the polymer in quantities sufficient to produce the desired flexibility or stiffness for various portions of the diaphragm. In some embodiments, different size graphene flakes are added to the polymer to produce the desired mechanical properties. The orientation of the graphene flakes may also be controlled to produce a composite mixture having particular properties. 
     In general, a center portion of the diaphragm may include more graphene flakes to make that area stiffer than the flexible portions to allow more flexibility in the flexible portion where the diaphragm may be attached to a support. The diaphragm may include a center portion including the graphene flakes and a flexible portion formed about the center portion. A greater amount of graphene flake material may be added to form to the center portion of a diaphragm as compared to a lesser amount of graphene flake material that may be added to form the flexible portion of the diaphragm. In some cases, no graphene flakes are added to portions that correspond to the flexible portion. 
     With regard to operation  602 , adding the graphene flakes may include varying the concentration of the graphene flakes for two or more distinct portions of the diaphragm. The size of the graphene flakes may also be varied as larger flakes will generally produce a stiffer end structure while smaller flakes produce a more flexible structure. In some implementations, multiple, separate composite mixtures are formed, each composite mixture having a different concentration and/or size of graphene flake, and each composite mixture may be used to form a different portion of the diaphragm. 
     Any portions of a diaphragm that are made separately may be joined together. For example, separate portions may be joined using an overmolding process, insert molding process, or co-molding process. The separate portions may also be bonded or attached using an adhesive or other mechanical joining technique. 
     In operation  603 , the diaphragm is formed by molding the composite mixture. The polymer and graphene composite mixture may be molded into a conical, conical dome, or other appropriate shape. Operation  603  may include any one of a variety of molding processes including, for example, injection molding, vacuum molding, pour molding, and the like. As part of the forming operation, the polymer graphene diaphragm may be cured to produce a diaphragm having the desired characteristics. 
     In general, the forming operation  603  may produce a diaphragm having variations in graphene concentration. For example, a first concentration of graphene flakes may be increased in a center portion of the dome structure as compared to a second concentration of graphene flakes in a flexible portion surrounding the center portion. The forming materials may include a first composite mixture having a first concentration of graphene flakes and a second composite mixture having a second concentration of graphene flakes that is less than the first concentration of graphene flakes. A center portion of the diaphragm may be molded using the first composite mixture and a flexible portion of the diaphragm surrounding the center portion may be molded using the second composite mixture. 
     The forming operation  603  may also produce a diaphragm having variations in graphene flake size. For example, the center portion may include a first size of graphene flake and the flexible portion may include a second size of graphene flake, where the first size is greater than the second size. The increased size of the graphene flake may result in a stiffer center portion as compared to the flexible portion. Different graphene flakes may be used to firm a first and second composite mixture, each composite mixture having a different size and/or concentration of graphene flakes. In some implementations, the center portion may be formed from a first mixture having a first size graphene flake that is larger than a second size graphene flake of a second mixture used to form the flexible portion of the diaphragm. 
     The center portion may also be formed from two or more portions, For example, forming the center portion of the diaphragm may further comprise forming an inner center portion having a first concentration of graphene flakes and forming an outer center portion having a second concentration of graphene flakes that is lower than the first concentration. The flexible portion may also be formed having a third concentration of graphene flakes that is lower than the second concentration. 
     In operation  604 , the diaphragm may be installed in an acoustic device. For example, the diaphragm may be connected to a diaphragm support and voice coil in accordance with the examples described above with respect to  FIGS. 2 and 3 . The acoustic device may form a speaker or microphone and may be incorporated into a housing or other portion of a portable electronic device. Operation  604  may be optionally performed as part of process  600 . 
       FIG. 7  is an illustrative block diagram of the electronic device  101  shown in  FIG. 1 . Electronic device  101  can include display  703 , processing device  704 , a memory  705 , an input/output (I/O) device  706 , a sensor  707 , a power source  708 , and a network communications interface  709  connected on a system bus  710 . Display  703  may correspond to the display  103  depicted in  FIG. 1 . Additionally or alternatively, the display  703  may include another display integrated into the device  101 . The display  703  may provide an image or video output for the electronic device  101 . Display  703  may be substantially any size and may be positioned substantially anywhere on, and may be operatively associated with, portable electronic device  101 . 
     The processing device  704  can control some or all of the operations of portable electronic device  101 . The processing device  704  can communicate, either directly or indirectly, with substantially all of the components of portable electronic device  101 . For example, a system bus or signal line  710  or other communication mechanisms can provide communication between the processing device  704 , the memory  705 , the I/O device  706 , the sensor  707 , the power source  708 , and/or the network communications interface  709 . 
     Processing device  704  can be implemented as any electronic device capable of executing instructions and carrying out operations associated with portable electronic device  101  as are described herein. Using instructions from device memory  705 , processing device  704  may, using I/O device  706 , regulate the reception and manipulation of input and output data between components of the electronic device  101 . Processing device  704  may be implemented in a computer chip or chips. Various architectures can be used for processing device  704  such as microprocessors, application specific integrated circuits (ASICs) and so forth. 
     Processing device  704  together with an operating system may execute computer code and manipulate data. The operating system may be a well-known system such as iOS, Windows, Unix or a special purpose operating system or other systems as are known in the art. Processing device  704  may include memory capability in memory  705  to store the operating system and data. Processing device  704  may also include application software to implement various functions associated with the portable electronic device  101 . 
     Memory  705  can store electronic data that can be used by the electronic device  101 . For example, memory  705  can store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, biometric images such as fingerprint images, data structures or databases, and so on. Memory  705  can be configured as any type of memory. By way of example only, memory  705  can be implemented as random access memory, read-only memory, flash memory, removable memory, or other types of storage elements, or combinations of such devices. 
     I/O device  706  can transmit and/or receive data to and from a user or another electronic device. One example of an I/O device is button  104  in  FIG. 1  which may include a tactile switch. The I/O device(s)  706  can include a display, a touch sensing input surface such as a trackpad, one or more buttons, one or more microphone devices  107  or speaker devices  106 , one or more ports such as a microphone port, and/or a keyboard. 
     The network communication interface  709  can facilitate transmission of data to or from other electronic devices. For example, a network communication interface can transmit electronic signals via a wireless and/or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular, Wi-Fi, Bluetooth, IR, and Ethernet. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20150630
Publication Date: 20180220
Grant Date: 20180220
Priority Date: 20150630
Inventors: LUZZATO VICTOR
POOLE JOSEPH C.
PREST CHRISTOPHER D.
Assignee: APPLE INC
CPC Classifications: [{"code": "B29C45/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2507/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R7/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R7/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C45/0001", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29L2031/38", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/0001", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29L2031/38", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R7/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R7/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2507/04", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 57684342