Acoustic transducer and microphone

#Field

#The present invention relates to an acoustic transducer and a microphone. Specifically, the present invention relates to a capacitance type of acoustic transducer configured by a capacitor structure made up of a vibrating electrode plate (diaphragm) and a fixed electrode plate. The present invention also relates to a microphone that employs this acoustic transducer.

#Related Art

#FIG. 1A is a schematic cross-sectional diagram of a conventional capacitance type of acoustic sensor. FIG. 1B is a schematic cross-sectional diagram showing how a diaphragm undergoes large deformation when a large degree of pressure is applied to the acoustic sensor in FIG. 1A. FIG. 1C is a schematic cross-sectional diagram showing how the diaphragm and a back plate undergo large deformation when an even larger degree of pressure is applied to the acoustic sensor in FIG. 1A.

#FIG. 2A is a plan view showing an acoustic sensor according to Embodiment 1 of the present invention. FIG. 2B is a plan view showing a state in which the diaphragm is exposed by removing the back plate and the fixed electrode plate from the acoustic sensor shown in FIG. 2A.

#FIG. 3 is an enlarged cross-sectional view of the acoustic sensor shown in FIG. 2A.

#The following describes embodiments of the present invention with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments, and various design modifications can be made within the scope of the present invention. In embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid obscuring the invention.

#The following describes an acoustic transducer according to Embodiment 1 of the present invention, that is to say an acoustic sensor 21, with reference to the drawings. FIG. 2A is a plan view of the acoustic sensor 21 according to Embodiment 1 of the present invention. FIG. 2B is a plan view of a state in which a diaphragm 24 is exposed by removing a back plate 28 and a fixed electrode plate 29 from the acoustic sensor 21 shown in FIG. 2A. FIG. 3 is a cross-sectional diagram of the acoustic sensor 21.

#The acoustic sensor 21 is a capacitance type of device created using MEMS technology. As shown in FIG. 3, in the acoustic sensor 21, the diaphragm 24 (vibrating electrode plate) is provided on a substrate 22, which is made of a silicon substrate or the like, via anchors 27, and the fixed electrode plate 29 is provided above the diaphragm 24 in opposition to the diaphragm 24.