Patent ID: 9197178
Filing Date: 2015-11-24
Classification: G10K,H03G,H04R

Abstract:
1. A headphone with active noise cancelling, comprising: a first gain amplifier, receiving a first noise audio signal and amplifying amplitude of the first noise audio signal to a second noise audio signal according to a first gain value; an active noise cancelling module, electrically connected to the first gain amplifier, the active noise cancelling module receiving the second noise audio signal and a first music audio signal and amplifying the first music audio signal to a second music audio signal, and generating a noise cancelling signal according to the second noise audio signal so as to superimpose the noise cancelling signal and the second music audio signal and then amplifying its power, and thus outputting an amplified synthetic audio signal; a speaker, electrically connected to the active noise cancelling module, for broadcasting the amplified synthetic audio signal, wherein the amplified synthetic audio signal and an external noise audio signal are superimposed as a noise-reduced music audio signal; a measure circuit, in a calibration mode, receiving the noise-reduced music audio signal and measuring a noise-reducing numerical value of the noise-reduced music audio signal; a calibration control circuit, electrically connected to the measure circuit for receiving the noise-reducing numerical value, the calibration control circuit outputting a gain calibration value according to a comparison result of the noise-reducing numerical value and a predetermined noise-reducing threshold value; and a Universal Serial Bus (USB) driving circuit, electrically connected to the calibration control circuit for receiving the gain calibration value, wherein the Universal Serial Bus (USB) driving circuit transmits the gain calibration value to the first gain amplifier via a General Purpose Input/Output (GPIO) interface for progressively adjusting the first gain value, so that the noise-reducing numerical value is larger than the predetermined noise-reducing threshold value.