Patent ID: 8638955
Filing Date: 2014-01-28
Classification: H04R

Abstract:
1. A voice input device comprising: a first microphone that includes a first diaphragm; a second microphone that includes a second diaphragm; and a differential signal generation section that generates a differential signal that indicates a difference between a first voltage signal obtained by the first microphone and a second voltage signal obtained by the second microphone based on the first voltage signal and the second voltage signal, and the differential signal generation section including: a delay section that delays at least one of the first voltage signal obtained by the first microphone and the second voltage signal obtained by the second microphone by a predetermined delay amount, and outputs the resulting signal; and a differential signal output section that receives the first voltage signal obtained by the first microphone and the second voltage signal obtained by the second microphone, at least one of the first voltage signal and the second voltage signal having been delayed by the delay section, generates a differential signal that indicates a difference between the first voltage signal and the second voltage signal, and outputs the differential signal; wherein the delay section is configured so that the predetermined delay amount is changed in accordance with a current that flows through a predetermined terminal; and a delay control section supplies the current, that controls the predetermined delay amount, to the predetermined terminal of the delay section, the delay control section including: i) a trimming resistor that is a resistor array in which a plurality of resistors or conductors are connected in series or parallel, or ii) at least one resistor, and wherein some of the resistors or conductors that form the resistor array are cut by a predetermined amount based on a result of a test, for determining a variation in delay amount, that is performed during the production process of the first and second microphones.