| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent a noise level from being increased by coupling an active audio signal which is the output of a noise headphone and a noise-canceling signal. <P>SOLUTION: The noise-canceling headphone uses a noise cancel circuit of reduced power consumption, and an audio input signal 120 is supplied directly to the headphone, without the use of additional headphone amplifier. The noise-canceling circuit uses a microphone 102 for picking up ambient noise to generate a signal of which the amplitude is equal to that of an ambient noise signal 130 but the polarity is opposite. As a result, the signal is mixed with the audio input signal and is supplied to a speaker of the headphone 116. This method uses fewer components than a normal noise cancel circuit and is advantageous, in that much less components are used, thereby also reducing power consumption. Since there is nothing amplified in an audio input signal mounted in the noise cancel circuit, distortions of the audio input signal are reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
