Patent ID: 9014380
Filing Date: 2015-04-21
Classification: H04L,H04R

Abstract:
1. A loudspeaker drive circuit comprising: an input for receiving an audio signal; and a signal processor for processing the audio signal before application to a loudspeaker having a membrane, and adapted to process the audio signal to derive a loudspeaker drive signal which results in the loudspeaker membrane moving asymmetrically and reaching its maximum displacement in both directions of displacement, wherein based on a prediction of asymmetrical excursion peaks the signal processor incorporates a DC offset in the loudspeaker drive signal in each direction of excursion of the loudspeaker membrane to limit a movement of the loudspeaker membrane asymmetrically in each direction, the DC offset is determined based on a measurement of a maximum excursion of the loudspeaker membrane in the each direction, and drive a loudspeaker with the loudspeaker drive signal, wherein the DC offset is set to zero and a gain of the audio signal is set to a fixed value if expected loudspeaker membrane displacement is below the maximum excursion.