Patent ID: 8077163

Claim:
A mobile device, comprising: a housing having first and second display areas; a mic-array integrated into the housing, the mic-array having a plurality of microphones operable to sense sound signals at multiple locations on the housing from a sound pen when handwriting an alphanumeric symbol on a surface separate from and in proximity to the housing; and a handwriting-to-text converter that graphically represents on the first display area simulated handwritten traces of the alphanumeric symbol and that converts the alphanumeric symbol into a computer-readable interchange code, representative of the alphanumeric symbol, for display on the second display area; wherein the mic-array comprises first and second microphones; wherein each emitted sound signal from the sound pen is sensed by the first and second microphones which creates two received sound signals y 1 (l) and y 2 (l) defined by y 1 ( l )=α 1 s ( l−t 1 )+η 1 ( l ) y 2 ( l )=α 2 s ( l−t 2 )+η 2 ( l ) where l is the discrete time index; t 1 and t 2 are the times needed for the two sound signals to travel from the sound pen to the first and second microphones, respectively; α i , i=1,2 is an amplitude of the received sound signal; η i , i=1,2 is background noise that is uncorrelated or independent to the emitted sound signal s(l) and to each other; and wherein a correlation of the two received sound signals depends on a relative time delay of arrival (TODA), τ=|t 1 −t 2 | where the time t 1 is the time of arrival at the first microphone and the time t 2 is the time of arrival at the second microphone.