Abstract:
The present invention is directed at a telephone that automatically selectively disables a microphone when the microphone is moved out of close proximity to the user&#39;s mouth. One embodiment comprises a sensor that detect if the telephone microphone is in close proximity to a user&#39;s mouth and a switch that selectively mutes the telephone in response to the detection.

Description:
FIELD OF THE INVENTION 
   The invention generally relates to telephone apparatuses. More particularly, the present invention provides a method and apparatus for automatically muting a telephone when it is taken away from a user&#39;s mouth. 
   BACKGROUND 
   Since Alexander Graham Bell uttered those famous words “Mr. Watson-come here-I want to see you”, the telephone has evolved into a necessity of modern living. Land-based telephone systems are now found in virtually every home and business in the United States. Recent developments in wireless phones have only magnified this popularity. 
   As would be expected for such a ubiquitous item, various cultural norms have grown up around the use of the telephone. One such norm is that it is considered rude to sneeze or cough into the telephone set. Another norm is that it is considered rude to discipline one&#39;s children while on the telephone. Unfortunately, the events leading to these situations are not always controllable, which forces users to pull the handset away from their mouth and cover it with their hand. This reaction, however, is inconvenient and does not completely eliminate the ability of the other caller to hear the sneeze, cough, or discipline. 
   One partial solution to these problems is a mute button. Although this feature is common on modern telephones, users frequently are not able to find it when the urge to cough, sneeze, or discipline children arises. 
   Clearly, there is a need for an automatic way to mute the phone when it is taken away from the user&#39;s head. 
   SUMMARY 
   The present invention is directed at a telephone that automatically mutes when it is taken away from a user&#39;s head. Accordingly, one aspect of the present invention is a method for automatically muting a telephone handset, comprising detecting if the microphone is in close proximity to a user&#39;s mouth, and in response to the detection, automatically muting the telephone. In some embodiments, detecting if a telephone microphone is in close proximity to a user&#39;s mouth comprises generating a light beam and directing the light beam at a photocell such that beam is blocked if the telephone handset is in close proximity to the user&#39;s face. In other embodiments, detecting if a telephone microphone is in close proximity to a user&#39;s mouth comprises detecting an angle from vertical for the telephone handset. 
   Another aspect of the present invention is an automatic muting telephone handset, comprising a microphone that generates communication signals in response to voice communications, a sensor that generates detection signals indicative of whether the microphone is in close proximity to a user&#39;s mouth, and a control circuit that switches the microphone between an active mode and a muted mode in response to the detection signals from the sensor. Yet another aspect of the present invention is an automatic muting telephone, comprising a sensor that detects when a telephone microphone is in close proximity to a user&#39;s mouth and a switch operably connected to the sensor that mutes the telephone. 
   One feature and advantage of the present invention is that it allows end users to mute the handset without having to make an affirmative action, such as pressing a mute button or holding their hands over the mouthpiece. Another feature and advantage is that the present advantage can be easily integrated into conventional handset designs. These and other features, aspects, and advantages will become better understood with reference to the following description, appended claims, and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is an isometric view of a telephone handset embodiment. 
       FIG. 2  is an isometric plan view of an alternate handset embodiment. 
       FIG. 3  is a sectional view showing the embodiment in  FIG. 2 . 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a side plan view of a telephone handset embodiment  100 . This handset  100  embodiment comprises a shock resistant plastic case  110  having tubular handle portion  120  connected to a hemispherical receiver housing  130  and a hemispherical speaker housing  140 . The receiver housing  130  has a planer ring-shaped surface  132 , a concave recess  134 , a microphone  136 , a plurality of air holes  138  that allow for sound waves to travel from the user to the microphone  136 , and a photoelectric detector  160 . The speaker housing  140  includes a planer ring-shaped surface  142 , a concave recess  144 , a speaker  146 , a plurality of air holes  148  that allow sound waves to travel between the speaker  146  and the user, and a light source  162 . The handset  100  further includes a communication cable  150  that enters the handset  100  through the receiver housing  130 , and plurality of internal wires  152  that allow for electrical communication signals to travel between the communication cable  150 , a switch  154 , the microphone  136 , a noise generator  156 , and the speaker  146 . 
   In operation, the light source  160  projects a beam of light  164  toward the photoelectric detector  162 . This light beam can pass between the light source  160  and the photoelectric detector  162  when the user is merely holding the handset  100 , but is interrupted when the user holds the speaker housing  160  against his or her ear. During those periods when the light beam  164  is interrupted (i.e., the light from the light source  162  does not strike the photocell  160 ), the switch  154  allows electrical communication to occur between the microphone  136  and the communication cable  150 . During those periods when the light beam  164  is not interrupted (i.e., when the light from the light source  162  strikes then photocell  160 ), the switch  154  does not allow electrical communication to occur between the microphone  136  and the communication cable  150 , but does activate the noise generator  156 . This, in turn, prevents the handset  100  from transmitting any sounds and causes the speaker  146  to emit a characteristic sound to alert the user that the handset  100  is muted. 
   The light source  162  can be any device capable of generating a beam of light  164  of sufficient strength to excite the photoelectric cell. It is desirable that the light source  162  also be capable of operation using the low voltage signals normally transmitted over telephone wires. One suitable light source  162  is comprised of a “Super Bright” light emitting diode (“LED”)  166 , available from Radio Shack under the part number 276-087A, and a lense  168  to focus the light at the photoelectric cell  160 . 
   The photoelectric detector  160  may similarly be any device capable of changing its electrical characteristics in response to being struck by the light source  162 . Again, it is desirable that the photoelectric detector  160  be capable of operation using the low voltage signals normally transmitted over telephone wires. One suitable photoelectric detector  160  is a cadmium sulphide cell sensor, such as that available from Radio Shack under the part number 276-1657. 
   The light source  162  and photoelectric cell  160  in this embodiment should be positioned such that the user&#39;s hand does not block the beam  164 , and such that the user&#39;s face blocks the beam  164  when the handset  100  is pressed against the user&#39;s face with the microphone  136  in close proximity to the user&#39;s mouth. One suitable location is to place the light source  162  and the photoelectric cell  160  as close to the speaker housing rim  142  and microphone housing rim  132 , respectively, as is possible. However, other locations are within the scope of the present invention. 
   The switch  154  may be any device capable of switching in response to the signal from the photoelectric cell the microphone  136  between an active mode, in which the telephone to which the handset  100  is attached transmits signals indicative of the user&#39;s voice, and a muted mode, in which the telephone to which the handset  100  is attached does not transmit signals indicative of the user&#39;s voice. In this embodiment, the switch comprises a field effect transistor (“FET”) that selectively opens and closes the circuit between connecting the microphone  136  to the communication cable  150 . 
   The noise generator  156  may be any device capable of switch should also be capable of generating a characteristic sound at the speaker  146  in response to the signal from the photoelectric cell  160 . This characteristic sound should be soft enough in volume that the user can still hear whatever is being transmitted over the telephone, and should be unusual enough that the user is unlikely to mistake the sound for anything else. One suitable noise generator is a D to A converter with an associated amplifier to produce an appropriate tone. Shutting off the speaker (no tone) is also a possible signalling mechanism. 
     FIG. 2  is an isometric view of a second telephone handset embodiment  200 . This handset  100  embodiment comprises a shock resistant plastic case  210  that defines a generally planar front surface  215 , a plurality of speaker air passages  215 , and a plurality of microphone air passages  225 ; a numeric keypad  230 , a liquid crystal display  235 , a power adaptor  240 , an antenna  245 , an infrared light source  250 , and an infrared light detector  255 . 
     FIG. 3  is a simplified sectional view of the handset  200  in  FIG. 2  in operation. This figure includes a portion of the user&#39;s face  310 , a switch operably connected the infrared detector  255  and to a microphone  340  via internal wires  330 . In operation, the infrared light source  250  projects a beam of infrared light  350  toward the user&#39;s face  310 . This beam reflects off the user&#39;s face  310  and into the infrared detector  255  when the user is holding the handset  200  in close proximity to his or her face  310 . This, in turn, causes the infrared detector  255  to generate an electrical signal, which closes the switch  320  and allows signals from the microphone  340  to travel to the antenna. When the handset  200  is not in close proximity to the user&#39;s face, however, the beam  350  does not strike the detector  255  with sufficient intensity to excite the detector  255 . This causes the switch  320  to remain in its open state, which prevents signals from passing between the microphone  340  and the antenna. Like the embodiment in  FIG. 1 , the embodiment in  FIGS. 2–3  may also use the switch  340  to causes the handset  200  to emit a characteristic sound from its speaker when the handset is muted. 
   The infrared light source  250  can be any device capable of generating the beam of infrared light  150  of sufficient strength to excite the infrared detector  255  if the user&#39;s face  310  is in close proximity. The infrared detector  255  may similarly be any device capable of changing its electrical characteristics in response to being struck by infrared light  350  reflected off the user&#39;s face  310 . One suitable emitter and detector combination is available from Sharp under the model number GPIU5. 
   Although the present invention has been described in detail with reference to certain examples thereof, it may also be embodied in other specific forms without departing from the essential spirit or attributes thereof. For example, the photoelectric sensing systems in  FIGS. 1–3  may be replaced or supplemented by other means of detecting whether the handset should be muted. Thus, for example, some embodiments may mount a pressure or capacitance sensor to the ring-shaped surface  142  that can detect when the handset  100 ,  200  is being held against the user&#39;s ear. Other embodiments may use sonic measuring devices, similar to those found in automatic focus cameras, to detect whether or not the handset is in close proximity to the user&#39;s face. 
   Still other embodiments of the present invention may also use a sensor, such as a mercury switch, capable of detecting an angle from vertical. These sensors in these embodiments would detect when a user holds the handset  100  or the handset  200  at an angle of more than about 90 degrees from vertical. These embodiments may be desirable because they can detect when the user pivots the microphone  136  or the microphone  340  away from his or her mouth, but keeps the speaker housing  140  or speaker  220  firmly placed against his or her ear. Those skilled in the art will appreciate that these sensors can be used in place of or in conjunction with the sensors described with reference to  FIGS. 1–3 . 
   The accompanying figures and this description depicted and described embodiments of the present invention, and features and components thereof. With regard to means for fastening, mounting, attaching or connecting the components of the present invention to form the mechanism as a whole, unless specifically described otherwise, such means were intended to encompass conventional fasteners such as machine screws, nut and bolt connectors, machine threaded connectors, snap rings, screw clamps, rivets, nuts and bolts, toggles, pins and the like. Components may also be connected by welding, friction fitting, adhesives, or deformation, if appropriate. Electrical connections or position sensing components may be made using appropriate electrical components and connection methods, including conventional components and connectors. Unless specifically otherwise disclosed or taught, materials for making components of the present invention were selected from appropriate materials, such as metal, metallic alloys, fibres, polymers and the like, and appropriate manufacturing or production methods including casting, extruding, molding and machining may be used. In addition, any references to front and back, right and left, top and bottom and upper and lower were intended for convenience of description, not to limit the present invention or its components to any one positional or spatial orientation. 
   Accordingly, it is desired that the embodiments described herein be considered in all respects as illustrative, not restrictive, and that reference be made to the appended claims for determining the scope of the invention.