Patent ID: 8682019
Filing Date: 2014-03-25
Classification: H04R

Abstract:
1. A unidirectional microphone comprising: an electrostatic microphone unit including a front acoustic terminal, a rear acoustic terminal and an electrode pin arranged at a side of the rear acoustic terminal, a cylindrical acoustic resistance tube housing the microphone unit and including a front end portion having a front opening, a rear end portion having a rear opening, a tube wall extending between the front end portion and the rear end portion, an acoustic resistance member attached to an inner surface of the tube wall, a front acoustic chamber and a rear acoustic chamber separated through the microphone unit in the acoustic resistance tube such that the front acoustic chamber is provided at a side of the front acoustic terminal and the rear acoustic chamber is provided at the side of the rear acoustic terminal, and a gap communicating the front acoustic chamber and the rear acoustic chamber and formed between an inner peripheral surface of the acoustic resistance tube and an outer peripheral surface of the microphone unit to pass low-frequency sound waves therethrough, a spacer attached to the rear opening of the acoustic resistance tube, an insulating cap mounted on the spacer, the spacer and the insulating cap blocking the rear opening of the acoustic resistance tube to prevent sound waves from entering the rear acoustic terminal through the rear opening and to guide the sound waves to the rear acoustic terminal of the microphone unit through the acoustic resistance member of the acoustic resistance tube, and a connector terminal arranged in the insulating cap and connecting the electrode pin in the rear acoustic chamber, wherein the front acoustic terminal is oriented toward the front end opening.