Abstract:
An apparatus for transmitting acoustic signals from a mobile communication device to the ears of a user and from the mouth of a user to the mobile communication device through a fiber optic link. A principal objective of the apparatus is to substantially reduce or eliminate radio frequency radiation exposure to the cranial regions of users of mobile communication devices. One embodiment of the apparatus implements an earphone and microphone system for use with a mobile telephone or other wireless communication device, using no electrical components within the earphone or microphone. The present invention implements a laser-actuated, sound-producing diaphragm as a hearing device. The laser may be contained within a housing connected to a wireless communication device. The laser may be connected to the hearing device by an optical fiber, thus enabling the housing containing the laser to be at a location remote from the hearing device. The housing may also contain a detector, capable of detecting phase changes corresponding to changes in the length of an optical path caused by modulation of a diaphragm used as a microphone.

Description:
BACKGROUND  
         [0001]    1. The Field of the Invention  
           [0002]    This invention relates to fiber optic communication systems and, more particularly, to novel systems and methods for reducing radio frequency exposure to the human anatomy by wireless communication devices.  
           [0003]    2. The Background Art  
           [0004]    The use of mobile telephones and wireless communication devices has increased dramatically in recent years. Such mobile communication devices produce varying degrees of radio frequency radiation during use. The increased use of such mobile communication devices has caused a corresponding increase in the exposure of low level radio frequency radiation to the bodies of users. In particular, users of mobile communication devices are experiencing markedly increased exposure in the cranial area, because many, if not most, mobile communication devices are designed to be held in close proximity to users&#39; ears during use.  
           [0005]    The time, duration, frequency, and intensity of such radiation exposure varies widely among users of mobile communication devices, depending on usage patterns and habits of users. For some users, exposure is frequent, prolonged, and intense. The intensity of exposure experienced by a particular user depends to a large extent on the technical characteristics of the mobile communication device used. Moreover, the intensity of radio frequency radiation produced varies greatly among commercially available embodiments of such devices.  
           [0006]    In an effort to ameliorate the radio frequency radiation exposure experienced by users and to make mobile communication devices easier to use, remote headphone and speaker systems have been developed and made commercially available. Wires connecting remote headphone or speaker systems to mobile communication devices such as mobile telephones typically extend toward the ears of a users to facilitate reception of signals by users&#39; ears and transmission of voice signals. Such wires are inherently conductors of radio frequency radiation, and these wires typically act as antennas receiving and directing radio signal power into and around the cranial region of users. Remote headphone and speaker systems do not, therefore, adequately abate radio frequency radiation exposure to users of mobile communication devices. “Wireless headsets” or “wireless earphone”, as they are sometimes called, frequently employ radio frequency transmission to deliver signals to the ears of a user from a base mobile communication unit, such as a mobile telephone. Such wireless headsets typically offer the advantage of reduced levels of radio frequency radiation at certain selected frequencies, as compared to radio frequency radiation levels produced by the typical base unit. While wireless headsets offer comparatively low levels of radio frequency exposure at certain frequencies, they actually produce higher levels of radio frequency radiation than the typical base unit at other frequencies. Moreover, “wireless headsets” or “wireless earphones” may be in even closer physical proximity to a user&#39;s cranial region during use than the typical base unit or other mobile communication device would be during use. Accordingly, the use of “wireless headsets” may actually increase radio frequency radiation exposure experienced by users of mobile communication devices.  
           [0007]    It would be an advancement in the art to provide a method and apparatus capable of remotely transmitting clear audio signals to the ear of a user from a communication device and clear voice signals from a microphone to a communication device, that would reduce or eliminate the radio frequency exposure typically experienced by users of mobile communication devices, particularly mobile telephones. It would be a further advancement in the art to eliminate the use of wires or electrical conductors to transmit signals to and from the cranial area of users of mobile communication devices.  
         BRIEF SUMMARY AND OBJECTS OF THE INVENTION  
         [0008]    In view of the foregoing, it is a primary object of the present invention to provide wireless earphone systems for use with mobile communication devices that provide reduced radio frequency radiation exposure to users of such communication devices.  
           [0009]    It is an object of the invention to provide an apparatus that employs a fiber optic link to transmit acoustic information from a mobile communication device such as a mobile telephone, thereby avoiding the problems associated with the use of wires or other conductors to transmit acoustic information in which the conductors (e.g. wires) direct radio frequency radiation toward the cranial regions of users.  
           [0010]    It is also an object of the invention to provide an apparatus that employs an earpiece capable of broadcasting the acoustic information transmitted over the fiber optic link into the ear of a user, thereby avoiding the comparatively higher levels of radio frequency radiation exposure experience by users “wireless headsets” or “wireless earphones” that receive radio frequency transmissions from base mobile communication units.  
           [0011]    Consistent with the foregoing objects, and in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed, in suitable detail to enable one of ordinary skill in the art to make and use the invention. In certain embodiments, an apparatus in accordance with the invention may include a connector, configured to communicate with a mobile communication device, such as a mobile telephone. The connector may be attached to a housing containing an photonic driver configured to convert an electrical signal to a photonic signal. Accordingly, the photonic signal is transmitted across an optical fiber to a photonic detector, typically housed within an earphone.  
           [0012]    In certain embodiments the photonic detector may be a photodiode, phototransistor, photodarlington pair, or a similar element capable of converting a photonic signal to an electrical signal. The earphone may amplify the electrical signal and transmit the signal to a sound producing diaphragm or earphone capable of producing sound within the audible range of a user. Likewise, the earphone may contain a battery to power the amplifier and other components contained within the device. Moreover, certain embodiments of the earphone may include a volume control and a mechanism to conserve power when the acoustic signal falls below a certain threshold value.  
           [0013]    In selected embodiments, the apparatus may integrate, into a single integrated system, the earphone with a microphone for receiving acoustic signals. That is, the signal from the microphone may use the same optical fiber as the earphone to transmit back to the mobile phone. The microphone or audio receiver may be configured to convert an acoustic impulse to an electrical signal and then to a photonic signal for transmission across the optical fiber. On the receiving end, a detector may detect the photonic signal and convert it to an electrical signal to produce an input to the mobile communication device (e.g. mobile telephone).  
           [0014]    In another selected embodiment, the system may be implemented so that no electrical signals are needed within the earphone and microphone, eliminating the need for a battery within said pieces. Such a configuration eliminates substantially all radio frequency radiation exposure that may be caused by electrical signals within the earphone or microphone. In this embodiment, a laser diode is used in the coupler connected to the mobile communication device to transmit across an optical fiber and actuate a laser driven diaphragm located in the earphone. A detector is also located in the previously mentioned coupler to detect displacements of a diaphragm (e.g. used as a microphone) through an optical fiber.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which:  
         [0016]    [0016]FIG. 1 is perspective view of one embodiment of a an apparatus for reducing radio frequency radiation exposure in accordance with the invention;  
         [0017]    [0017]FIG. 2 is a schematic block diagram of an audio transmission component of the apparatus of FIG. 1;  
         [0018]    [0018]FIG. 3 is a schematic block diagram of one embodiment of a microphone component of the apparatus of FIG. 1;  
         [0019]    [0019]FIG. 4 is a schematic diagram of one alternative embodiment for the audio component of the apparatus of FIG. 1 that uses a sound producing diaphragm remotely located from the earphone;  
         [0020]    [0020]FIG. 5 is a perspective view of one embodiment of the apparatus integrating both the audio and microphone components;  
         [0021]    [0021]FIG. 6 is a schematic block diagram illustrating additional detail of the apparatus of FIG. 5; and  
         [0022]    [0022]FIG. 7 is a schematic block diagram illustrating one embodiment of an integrated system in which neither the earphone nor the microphone use any electronic components. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in FIGS. 1 through 7, is not intended to limit the scope of the invention, as claimed, but is merely representative of the presently preferred embodiments of the invention. The presently preferred embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.  
         [0024]    Those of ordinary skill in the art will, of course, appreciate that various modifications to the details of the Figures may easily be made without departing from the essential characteristics of the invention. Thus, the following description of the Figures is intended only by way of example, and simply illustrates certain presently preferred embodiments consistent with the invention as claimed.  
         [0025]    Referring to FIG. 1, one presently preferred embodiment of an apparatus  10  for reducing antennae effects in speaker cords may include a coupling element  14  connected to a mobile communication device  12 . The coupling element  14  may be configured to modulate an electrical audio signal received from the mobile communication device  12  to a photonic signal for transmission across an optical fiber  16 . Accordingly, the photonic signal may be received by an earphone  18  to produce an acoustic impulse corresponding to the hearing range of a listener.  
         [0026]    Likewise, another optical fiber  15  may be provided to transmit photonic inputs to the coupler  14  from a microphone (as illustrated in FIG. 3), as desired. The coupler  14  may then convert the photonic inputs from the microphone into electrical audio signals for transmission to the mobile communication device  12 .  
         [0027]    Referring to FIG. 2 while continuing to refer generally to FIG. 1, an apparatus  10  may include a connector  20  for coupling to a communication device  12 . Such a connector  20  may comprise a typical cylindrical jack or other type of connector suitable to connect to a corresponding receptacle within the communication device  12 . The connector body may attach to a housing  24  enclosing the interior components of a coupling element  14 .  
         [0028]    The connector  20  may transmit an electrical signal from the communication device  12  through lines  26   a,    26   b  to a conversion element 30 a,  which may comprise a photodiode, phototransistor, photodarlington pair, or the like, suitable for converting an electrical signal into a photonic signal. In the depicted embodiment, the conversion element 30 a  converts the electrical signal from the communication device to a photonic signal  31   a  for transmission across an optical fiber  16  to an earphone  18 .  
         [0029]    The earphone  18  may comprise a housing  21  containing a detector  32   a  that receives, detects, and converts the photonic signal  31   a  into an electrical signal. An amplifier  38  may then amplify and send the electrical signal to a sound producing diaphragm  44  for conversion to an audible impulse. In the depicted embodiment, the audible impulse is projected through an hearing channel  46 , which may be attached to the housing  21 .  
         [0030]    The housing  21  of the earphone  18  may contain a battery  40  to supply power to the amplifier  38 . Thus, an audio signal may be transmitted across an optical fiber  16  for eventual reproduction to an audible impulse signal corresponding to the hearing range of a user.  
         [0031]    Referring to FIG. 3, another presently preferred embodiment of the apparatus  10  may include an audio receiver  19  or a microphone  19 . The microphone  19  may include a diaphragm  54  configured to receive and detect acoustic impulses and an actuator  56  configured to generate an electrical signal corresponding to the acoustic impulses. The microphone  19  may further include a converter  32   b  configured to convert electrical signals into photonic signals and lines  34   b  and  36   b  configured to transmit electrical signals. The converter  32   b  may comprise a photodiode, phototransistor, photodarlington pair, or the like, suitable for converting an electrical signal into a photonic signal.  
         [0032]    For example, in the depicted embodiment, when the diaphragm  54  detects an acoustic impulse (e.g. voice signal or the like), the diaphragm drives the actuator  56  to generate an electrical signal corresponding to the detected acoustic impulse. The electrical signal may be transmitted across lines  34   b,    36   b  to energize the converter  32   b,  which then converts the electrical signal into a photonic output  31   b.  The photonic output  31   b  may be subsequently transmitted over an optical fiber  15  to a remote detector located in a coupling element  14 .  
         [0033]    When the photonic signal  31   b  arrives at the coupling element  14 , a detector  30   b  (such as a photodiode, phototransistor, photodarlington pair, or the like) may detect and convert the photonic signal  31   b  into an electrical signal. The electrical signal may then be transmitted across the lines  26   b,    28   b  to an amplifier  38   b  to be amplified and sent to a mobile communication device  12  through a connector  20 .  
         [0034]    In selected embodiments, the signal received from the detector  30   b  is not amplified, and therefore passes directly from the detector  30   b  through the lines  26   b,    28   b  to the connector  20  and into the communication device  12 . The amplifier  38   b  may receive power from a power source contained in or associated with the coupling element  14 , or, alternatively, the amplifier  38   b  may receive power from the mobile communication device  12 .  
         [0035]    Referring to FIG. 4 while continuing to refer generally to FIGS.  1 - 3 , another presently preferred embodiment of the apparatus  10  may include a sound producing diaphragm  48  located in a coupling element  14 . In the depicted embodiment, the sound producing diaphragm  48  may receive an electrical audio signal through lines  26 ,  28  from a mobile communication device  12 . The diaphragm  48  may produce an audible signal  31   c,  which may be transmitted through a channel  50 . The channel  50  may comprise a hollow tube formed of rubber, plastic, or suitable material.  
         [0036]    Accordingly, an earphone  52  may receive the audible signal  31   c  from the channel  50 . The earphone  52  typically delivers the audible signal  31   c  to the ear of a user. The earphone  52  may be configured to modify (e.g amplify or attenuate) the intensity of the audible signal  31   c  to ensure the audible signal  31   c  is within the hearing range of a user upon delivery to the user&#39;s ear. The embodiment of FIG. 4 may be implemented to eliminate electrical components used in the earphone  52  of the embodiment of FIG. 2.  
         [0037]    Likewise, a configuration similar to the configuration of FIG. 4 may be implemented with respect to a microphone  19 . In other words, the microphone  19  could be housed within a coupling element  14 , which is remote from a user. In such a configuration, a channel  50  may connect a mouthpiece configured to receive a voice input from a user and a coupling element  14  containing a microphone  19 . The voice input of a user could thus be transmitted from the mouthpiece through the channel  50  to the microphone  19  housed in the coupling element  14 .  
         [0038]    Referring to FIG. 5 while continuing to refer to FIGS.  1 - 4  generally, another alternative embodiment of the apparatus  10  may include an earphone  18  and a microphone  19  integrated jointly to employ a single optical fiber  16 . Since transmission of light signals may be extremely fast and efficient, multiplexing the signals to the earphone and from the microphone may travel over a single optical fiber  16 . FIG. 5 illustrates an earphone  18  and microphone  19  merged into a single cord  16  or fiber optic channel  16 . However, the apparatus  10  may be implemented in other configurations, such as having separate fiber optic cords to the microphone  19  and earphone  18  or integrating the microphone  19  and earphone  18  into a headset structure.  
         [0039]    Referring to FIG. 6 while continuing to refer to FIG. 5, a microphone and earphone (as described in FIG. 2 and FIG. 3) may be integrated to use a common optical fiber  16  and coupling element  14 . For example, an earphone  18  may be configured to receive a photonic signal  31   a  across a fiber  16  from a conversion element  30   a.  Likewise, a microphone  19  may be configured to transmit an audio signal  31   b  to a detector  30   b  across the fiber  16 . Coupling element  14  may be configured to house both the conversion element  30   a  and the detector  30   b  connected to the connector  20  through lines  26   a,    27 ,  28   a.  Likewise, an amplifier  38   b  may be included in the housing  24  to amplify the signal from the detector  30   b  received through lines  26   b,    28   b.    
         [0040]    Referring to FIG. 7, one embodiment wherein neither the earphone nor the microphone are comprised of any electrical components, is illustrated. A benefit of implementing the present invention in this configuration is that electromagnetic radiation exposure near the cranial area of a user is greatly reduced or eliminated. A coupling element  14  may comprise a laser diode  81  or laser source  81 , which may produce a modulated laser signal  31   a  containing audio information. The laser signal  31   a  is transmitted to the end  82  of optical fiber  16   a,  which is adapted to propagate modulated light from the end  82  thereof to a diaphragm  84 .  
         [0041]    The diaphragm  84  may be ferromagneticly impregnated and be sustained in a concave posture by a magnetized screen  86 . The diaphragm  84  may absorb light received from the end  82  of the optical fiber  16   a  and, consequently, may be heated or cooled causing expansion or contraction, thus producing a sound field  90 . The sound field  90  may then be directed through a hearing channel  46  to the ear of a user.  
         [0042]    A reflective shield  88  may be located behind the end  82  of the optical fiber  16   a  to reflect any excess energy toward the diaphragm  84 . Likewise, the end  82  of the optical fiber  16   a  may be coated with a anti-reflective material to prevent light from reflecting back down the fiber  16   a.    
         [0043]    The embodiment of FIG. 7 may also include an optically-driven microphone  19 . An acoustic impulse  77  corresponding to the voice of a user may be received by the optically driven microphone  19 . The acoustic impulse  77  may actuate a diaphragm  78  causing a displacement in directions  92 ,  94 . In the embodiment, an optical fiber  16   b  is coiled around the diaphragm  78  and is stretched upon displacement of the diaphragm  78  causing the path length of the optical fiber  16   b  to change. Consequently, a detector  57 , positioned in the coupling element  14  may be configured to detect changes in path length and output an electrical audio signal  76  corresponding to modulation of the diaphragm  78 .  
         [0044]    Referring to the detector  57 , a laser reference source  58  may produce apolarized laser output  62  incident on an amplitude splitter  60 , which splits the signal into daughter signals  64 ,  66 . The signal  64  passes through a polarization splitter  70  (i.e. transmits light of a specific polarization and reflects light not of that polarization) and travels through the optical fiber  16   b,  which may be a birefringent fiber in order that the signal  64  maintain a constant angle of polarization. The signal  64  may be transmitted through the optical fiber  16   b  and reflected by the reflective end  80  of the fiber, configured to change the signal polarization by 90 degrees and produce a signal  72 .  
         [0045]    The signal  72  is subsequently reflected back towards the detector  57  where it may be incident on the polarization splitter  70  and reflected toward mirrors  68   d,    68   c  into a photodetector  74 . Meanwhile, laser reference signal  66  is reflected by mirrors  68   a,    68   b  into the photodetector  74 . The photodetector may be configured to compare the two signals  66 ,  72  and detect any phase change in signal  72  caused by displacement of the diaphragm  78 , which alters the path length of fiber  16   b.  That is, the photodetector  74  may compare the signal  72  to the reference signal  66  to detect any shifts in phase caused by acoustic impulses at the microphone  19 . Accordingly, an electrical audio signal is transmitted to the connector  20  corresponding to fluctuations in the diaphragm  78 .  
         [0046]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.