Patent ID: 6647118
Filing Date: 2003-11-11
Classification: H04M,H04R

Abstract:
A noise canceling microphone unit for use in a handset having a closed housing defining a microphone receiving space therein, said housing having a lower member with a mouthpiece surface and an upper member with a side surface, said noise canceling microphone unit being mounted in said microphone receiving space and comprising:a noise canceling microphone element having first and second acousto-electric transducers facing first and second sound sensing surfaces, respectively, at opposite ends of said noise canceling microphone element to produce an electric signal representing a sound difference between a first sound sensed at said first sound sensing surface and a second sound sensed at said second sound sensing surface; a microphone holder for fixedly holding said noise canceling microphone element therein, said microphone holder comprising: a hollow cylinder having opposite first and second open ends, said first open end facing said mouthpiece surface when said microphone holder is mounted in said microphone receiving space, said hollow cylinder fixedly holding therein said noise canceling microphone element with said first sound sensing surface being directed to but short of said first open end while said second sound sensing surface directed to but short of said second open end; and a vent tube laterally extending from said hollow cylinder and opening in said hollow cylinder at a position between said second open end and said second sound sensing surface of said noise canceling microphone element held in said hollow cylinder, said vent tube having an extending open end, said extending open end being inserted into an opening formed in said side surface to be opened to the outside of said housing when said microphone holder is mounted on said lower member in said microphone receiving space; and a circuit board connected to said noise canceling microphone element and mounted on said hollow cylinder to close said second open end.