Patent Publication Number: US-2006018499-A1

Title: Acoustic resonator/diffuser system and method

Description:
FIELD OF THE INVENTION  
      The present invention generally relates to the field of acoustic systems, and more particularly relates to acoustic systems incorporating acoustic resonators and diffusers closely coupled to the ear.  
     BACKGROUND OF THE INVENTION  
      The acoustic response of a system and the ease at which the user can locate the system to his/her ear both influence the perceived audio performance of an earpiece of an electronic device. The ease with which the user can locate the acoustic system is primarily a function of the surface area through which the phone emits sound. This area is influenced by the number, size, and relative location of ports that lead from the earpiece transducer to the listening surface of the phone. An acoustic system that has multiple ports spread over a large surface will be easily located by the user.  
      The acoustic response of an earpiece system can be enhanced by designing an acoustic resonator between the earpiece transducer and the listening surface of the device. This resonator often includes a small resonant air volume that is directly in front of the transducer. The resonator also includes a single, small port connecting that small air volume with the listening surface of the device. Generally, an acoustic resonator of this form severely compromises the ease with which the user is able locate the acoustic system to his/her ear. In order to improve the ease with which the user can locate the acoustic system, holes are added to the system. These additional holes, however, cause a loss of the resonating effects. As a result, designers select among trade offs between acoustic response and the ease with which the user can locate the acoustic system.  
      Therefore a need exists to overcome the problems with the prior art as discussed above.  
     SUMMARY OF THE INVENTION  
      Briefly, in accordance with the present invention, an acoustic system has an acoustic transducer for producing a first sound pressure signal and at least one acoustic resonator that is located in proximity to the acoustic transducer and that accepts the first sound pressure signal. The acoustic resonator produces a second, enhanced sound pressure signal. The acoustic system further has at least one acoustic diffuser that accepts the second, enhanced sound pressure signal and diffuses the second, enhanced sound pressure signal.  
      In accordance with another aspect of the present invention, a method for producing sound pressure signal includes generating a first sound pressure signal, creating a second, enhanced sound pressure signal by creating a resonance for the first sound pressure signal, and diffusing the second sound pressure signal.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.  
       FIG. 1  illustrates an acoustic system according to an exemplary embodiment of the present invention.  
       FIG. 2  is a detailed illustration of the back sides of acoustic resonator and acoustic diffuser in accordance with an exemplary embodiment of the present invention.  
       FIG. 3  illustrates an exploded view of an electronic device incorporating an acoustic system according to the exemplary embodiment of the present invention.  
       FIG. 4  illustrates an electronic device front view according to the exemplary embodiment of the present invention.  
       FIG. 5  illustrates a cut-away internal down view “A” as is denoted in  FIG. 4  of an acoustic system for an electronic device in accordance with an exemplary embodiment of the present invention.  
       FIG. 6  illustrates a cut-away internal side view “B” as is denoted in  FIG. 4  of an acoustic system for an electronic device in accordance with an exemplary embodiment of the present invention.  
       FIG. 7  illustrates a cellular phone block diagram according to an exemplary embodiment of the present invention.  
       FIG. 8  illustrates an acoustic sound pressure generation processing flow diagram according to an exemplary embodiment of the present invention.  
       FIG. 9  illustrates a first alternative acoustic system in accordance with the present invention.  
       FIG. 10  illustrates a second alternative acoustic system in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION  
      As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention.  
      The terms “a” or “an”, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language). The term coupled, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.  
      The exemplary embodiments of the present invention, as described below, provide a physically small and power efficient sound generating acoustic system that can be easily placed at a proper location relative to a user&#39;s ear.  
       FIG. 1  illustrates an acoustic system  100  according to an exemplary embodiment of the present invention. Acoustic system  100  includes an acoustic transducer  102  that accepts an electrical signal over input wires  116  and generates an acoustic sound pressure output signal at its face  118 . The acoustic transducer of the exemplary embodiment is an electromagnetic speaker acoustic transducer that produces a sound pressure output at its face  118 . Further embodiments of the present invention incorporate any type of acoustic transducer, including but not limited to piezo-electric acoustic transducers  
      The acoustic system  100  of the exemplary embodiment further includes an acoustic resonator  104 . Acoustic resonator  104  has a back end that is in proximity to, and is adjacent to by being attached in this exemplary embodiment to, the acoustic transducer&#39;s face  118 . The acoustic resonator  104  forms a resonant volume within a resonant cavity  106  that is shown here in outline but further described below. The resonant cavity  106  is in proximity to the output of the acoustic transducer  102  in the exemplary embodiment. The resonant cavity  106  of the exemplary embodiment has a single acoustic output port  112  on the front end of the acoustic resonator  104 , which is the end opposite the back end of the acoustic resonator  104 , i.e., the end that is connected to the acoustic transducer  102 . The operation of the acoustic resonator  104 , and particularly the resonant cavity  106  defined by the acoustic resonator  104 , improves the acoustic performance of the acoustic transducer  102  as is known by ordinary practitioners in the relevant arts. The resonant cavity  106  of the exemplary embodiment is optimized for voice signals, and is designed to resonate in the area of three Kilohertz (KHz). Further embodiments design resonant cavities  106  and output port  112  to resonate at different frequencies in order to emphasize other types of audio. Various embodiments of the present invention also include one or more output ports  112 . The acoustic resonator accepts the sound pressure signal from the acoustic transducer  102  and produces an enhanced sound pressure signal at the output port  112 . Further embodiments include a resonator to produce enhanced sound pressure signal at other locations, such as at the front of an acoustic transducer or at an acoustic output port, as is discussed below.  
      The acoustic system  100  of the exemplary embodiment further includes an acoustic diffuser housing  108 . Acoustic diffuser housing  108  of the exemplary embodiment forms a diffuser cavity  110  that is a small air volume that is located in proximity to the front of the single resonator port  112 . In the exemplary embodiment, the diffuser cavity  110  is directly in front of the resonator output port  112  and receives the sound pressure output of the acoustic resonator  104  as is delivered through the resonator output port  112 . The diffuser cavity  110  of the exemplary embodiment has an acoustic cover  120  at its output end, which is the end opposite the acoustic resonator output port  112 . The acoustic cover  120  has multiple diffuser output ports that connect the diffuser cavity  110  to a listening surface of a device incorporating the acoustic system  100 . The acoustic cover  120  and diffuser cavity  110  in the exemplary embodiment form an acoustic diffuser to diffuse enhanced sound pressure signals produced by the combination of acoustic transducer  102  and acoustic resonator  104 .  
      The acoustic diffuser housing  108  of the exemplary embodiment accepts the sound pressure output from the acoustic resonator output port  112  and diffuses/spreads this sound pressure acoustic signal across an area of the surface of the acoustic cover  120  of the acoustic system  100 . Diffusing/spreading this sound pressure signal across this greater area facilitates properly locating the sound system  100  at the ear of the user. The acoustic diffuser housing  108 , in combination with the acoustic resonator  104 , creates an acoustic system  100  that is able to be optimized for both performance and ease of location without compromising either of these properties.  
       FIG. 2  is a detailed illustration of the back sides of acoustic resonator  104  and acoustic diffuser housing  108  in accordance with an exemplary embodiment of the present invention. The acoustic resonator  104  of the exemplary embodiment is formed from stamped metal. Further embodiments utilize other materials to form the acoustic resonator  104  such as molded plastics and other such materials. The acoustic diffuser housing  108  and acoustic cover  120  are similarly able to be constructed of various materials.  
      The back side of acoustic resonator  104  is shown to form the resonant cavity  106  by a stamped recess on the back surface of acoustic resonator  104 . This stamped recess includes the output port  112  as a single output hole within the sheet metal that forms the stamped recess. Acoustic diffuser housing  108  of the exemplary embodiment is a molded part that is molded to form a diffuser cavity  110 . Hole  114  is molded in the acoustic diffuser housing  108 .  
       FIG. 3  illustrates an exploded view of an electronic device  300  incorporating an acoustic system  100  according to the exemplary embodiment of the present invention. The exploded view of the electronic device  300  in the exemplary embodiment shows the top part of a flip-type cellular phone that includes an acoustic system  100 , as is described above. Flip-type cellular phone designs are well known to ordinary practitioners in the relevant arts. Further embodiments incorporate an acoustic system according to the present invention, such as the exemplary acoustic system  100 , into other types of cellular phones, such as monolith type cellular phones. Further embodiments incorporate an acoustic system according to the present invention into other types of audio devices, including but not limited to audio devices that process digitized audio information, such as MP3 players and other devices that produce audio sounds.  
      The acoustic diffuser housing  108  is formed as part of a lens structure  302  in the exemplary embodiment. Lens structure  302  of the exemplary embodiment includes a clear plastic structure that covers an alphanumeric display for the electronic device (not shown). Acoustic diffuser housing  108  has a diffuser cavity  110  that is covered by acoustic cover  120  on the end opposite the end of the diffuser cavity  110  that is in proximity to the output port  112  of the resonant cavity  106 .  
      The exploded view of an electronic device  300  includes a device back structure  306  that forms a sturdy support structure for the electronic device. A metallic back  308  is further included to provide an aesthetically pleasing appearance for the electronic device. The acoustic transducer  102  and acoustic resonator  104  are placed between the device back structure  306  and the lens structure  302 . Acoustic cover  120  is placed on the side of the lens structure  302  that is opposite the side of the lens structure in contact with the acoustic resonator  104 .  
       FIG. 4  illustrates an electronic device front view  400  according to the exemplary embodiment of the present invention. Front view  400  illustrates a front view of the top part of the flip-type cellular phone as is illustrated in  FIG. 3 . The acoustic cover  120  is illustrated in this front view  400 . The other components of the acoustic system  100  are located behind acoustic cover  120  in this exemplary embodiment. Front view  400  further illustrates the orientation of an internal down view “A” and an internal side view “B” as are illustrated in the following figures.  
       FIG. 5  illustrates an internal down view “A”  500  as is denoted in  FIG. 4  of an acoustic system  100  for an electronic device in accordance with an exemplary embodiment of the present invention. Internal down view  500  illustrates a sound transducer  102 , an acoustic resonator  104  and an acoustic diffuser housing  108  in their assembled positions. An acoustic cover  120  is shown at the outside end of acoustic diffuser housing  108 . The acoustic cover  120  is further shown to have a number of diffuser ports  520  that form output ports for the diffuser cavity  110  to allow transmission of sound out of the acoustic system  100  for the user to hear. The diffuser ports  520  are physically dispersed across the acoustic cover  120  so as to facilitate location of the output of the acoustic diffuser, via the acoustic cover  120 , at a proper location near a user&#39;s ear. The diffuser ports  520  further facilitate delivery of a dispersed sound pressure signal to a user&#39;s ear. Further embodiments of the present invention utilize diffuser ports that consist of one or more holes and/or one or more slots. A perforated screen  522  is also located between the diffuser ports  520  and the resonant cavity  110  in the exemplary embodiment in order to, for example, protect from foreign material and water intrusion in this design.  
      Internal down view  500  illustrates various dimensions for the components of the acoustic system  100  of the exemplary embodiment. The resonator cavity  106  of the exemplary embodiment has a resonator cavity width  502  of 4.30 mm and a resonator cavity depth  504 , which is the distance from the edge of the resonator cavity to the acoustic transducer face  118 , of 0.60 mm. The output port  112  of the resonant cavity  106  in the exemplary embodiment has a diameter of 2.00 mm. As an example, the thickness of the metal plate that forms the acoustic resonator  104  has a resonator wall thickness  508  of 0.20 mm.  
      The acoustic diffuser cavity  110  of the exemplary embodiment has a diffuser cavity width  510  of 7.30 mm. The diffuser depth  512  of the exemplary embodiment, which is the distance from the inside surface of the acoustic cover  120  to the protruding edge of the sound resonator  104 , is 0.70 mm.  
       FIG. 6  illustrates an internal side view “B”  600  as is denoted in  FIG. 4  of an acoustic system  100  for an electronic device in accordance with an exemplary embodiment of the present invention. Internal side view  600  illustrates various dimensions for the components of the acoustic system  100  of the exemplary embodiment as looking from the side of the acoustic device  100 . The acoustic resonator cavity  106  of the exemplary embodiment has a resonator cavity height  606  of 5.00 mm. The acoustic diffuser cavity  110  of the exemplary embodiment has a diffuser cavity height  604  of 10.00 mm. Diffuser ports  520  have essentially a round cross section in the exemplary embodiment. The diffuser port diameter  602  is 0.80 mm in the exemplary embodiment. The diffuser ports  520  can have a diffuser port depth  608 , which is the thickness of the material forming the acoustic cover  120 , of 0.15 mm.  
       FIG. 7  illustrates a cellular phone block diagram  700  according to an exemplary embodiment of the present invention. The cellular phone block diagram  700  describes a cellular phone that is a device including an embodiment of the present invention. The cellular phone block diagram  700  includes an RF antenna  702 , a RF receiver  704  and an RF transmitter  706 . The RF transmitter  706  and RF receiver  704  are connected to the RF antenna  702  in order to support bi-directional RF communications. The cellular phone  700  is able to simultaneously transmit and receive voice and/or data signals. The RF receiver  704  provides voice data to an audio processor  708  and the audio processor  708  provides voice data to the RF transmitter  706  to implement voice communications. The audio processor  708  obtains voice signals from microphone  712  and generates audio signals that are provided to the acoustic system  100  as an input to the speaker/acoustic transducer  102 , which operates as described herein. The RF receiver  704 , RF transmitter  706 , Audio processor  708 , microphone  712  and acoustic system  100  operate to communicate voice signals to and from the cellular phone  700 .  
      The cellular phone block diagram  700  includes a controller  716  that controls the operation of the cellular phone in the exemplary embodiment. Controller  716  is connected to the various components of the cellular phone block diagram  700  via control bus  722 . Controller  716  communicates data to external devices (not shown), such as a base station and/or a server, through a wireless link. Controller  716  provides data to and accepts data from data processor  714 . Data processor  714  of the exemplary embodiment performs communications processing necessary to implement over-the-air data communications to and from external devices. Data processor  714  provides data for transmission to the RF transmitter  706  and accepts received data from RF receiver  704 .  
      Controller  716  provides visual display data to the user through display  742 . Display  742  of the exemplary embodiment is a Liquid Crystal Display that is able to display alphanumeric and graphical data. Controller  716  also accepts user input from keypad  718 . Keypad  718  is similar to a conventional cellular phone keypad and has buttons to accept user input in order to support operation of the exemplary embodiment of the present invention.  
      The cellular phone block diagram  700  further includes non-volatile memory  726 . Non-volatile memory  726  stores program data and more persistent data for use by the controller  716 . Data stored in non-volatile memory  726  of the exemplary embodiment can be changed under control of controller  716  if called for by particular processing performed by the controller  716 . The cellular phone block diagram  700  further contains volatile memory  724 . Volatile memory  724  is able to store transient data for use by processing and/or calculations performed by the controller  716 .  
       FIG. 8  illustrates an acoustic sound pressure generation processing flow diagram  800  according to an exemplary embodiment of the present invention. The acoustic sound pressure generation processing flow begins by generating, at step  802 , a sound pressure signal. The sound pressure signal is generated in the exemplary embodiment by acoustic transducer  102 . The sound pressure signal generation processing flow then creates, at step  804 , an acoustic resonance for the sound pressure signal. This resonance is created in the acoustic resonator  104  in the exemplary embodiment. The created resonance produces a resonator output sound pressure signal. The sound pressure signal generation processing flow then diffuses, at step  806 , the resonator output sound pressure signal as an acoustic output for the device performing this process. The above described sound pressure signal generation processing flow continues for as long as sound is being generated.  
       FIG. 9  illustrates a first alternative acoustic system  900  in accordance with the present invention. The first alternative acoustic system  900  positions a resonator  902 , with a resonant cavity  904 , in proximity to the back of an acoustic transducer  910 . The first alternative acoustic system  900  also locates a diffuser  906  in proximity to the front of the acoustic transducer  910 . The operation of the first alternative acoustic system  900  causes an enhanced sound pressure signal to be produced at the front of acoustic transducer  910 . This enhanced sound pressure signal produced at the front of acoustic transducer  910  is diffused by diffuser  906 .  
       FIG. 10  illustrates a second alternative acoustic system  1000  in accordance with the present invention. The second alternative acoustic system  1000  includes an acoustic channel  1010  in front of an acoustic transducer  1002 . The second alternative acoustic system  1000  connects a resonator  1004 , with a resonant cavity  1006 , to the acoustic channel  1010 . The resonator  1004  in this second alternative acoustic system  1000  is not directly in the path of the acoustic sound pressure signal. The operation of the second alternative acoustic system  1000  causes an enhanced sound pressure signal to be produced at the output of acoustic channel  1010  due to the operation of resonator  1004 . The second alternative acoustic system  1000  locates a diffuser  1008  in proximity to the output of the acoustic channel  1010  to diffuse the enhanced sound pressure signal. Further embodiments place one or more resonator cavities in various locations relative to one or more acoustic transducers and/or diffusers.  
      Although specific embodiments of the invention have been disclosed, those having ordinary skill in the art will understand that changes can be made to the specific embodiments without departing from the spirit and scope of the invention. The scope of the invention is not to be restricted, therefore, to the specific embodiments. Furthermore, it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the present invention.