Sensing method for a capacitive touch system

Abstract

A capacitive touch system uses at least two touch integrated circuits to simultaneously scan a touch panel, each of the touch integrated circuits only for scanning a portion of the traces of the touch panel. Therefore, the capacitive touch system can maintain a good frame rate, even the touch panel is a large scale touch panel. Sensing methods are provided to determine a sensed value for a boundary trace which is the last one of the traces connected to a first touch integrated circuit and prior to the first one of the traces connected to a second touch integrated circuit.

1 . A sensing method for a capacitive touch system including a touch panel having a plurality of first traces and a plurality of second traces, of which the first one of the plurality of second traces is next to the last one of the plurality of first traces, the sensing method comprising the steps of:
 (A) scanning the plurality of first traces by a first touch integrated circuit and the plurality of second traces by a second touch integrated circuit, each of the plurality of first traces except the last one thereof providing a first. ADC value, each of the plurality of second traces providing a second ADC value;   (B) selecting at least one from the first ADC values and at least one from the second ADC values; and   (C) calculating with the selected ADC values to determine a sensed value for the last one of the plurality of first traces.   
     
     
         2 . The sensing method of  claim 1 , wherein the step C comprises averaging the selected ADC values to obtain an average thereof as the sensed value for the last one of the plurality of first traces. 
     
     
         3 . The sensing method of  claim 1 , wherein the step C comprises low-pass filtering the selected ADC values to determine, the sensed value for the last one of the plurality of first traces. 
     
     
         4 . A sensing method for a capacitive touch system including a touch panel having a plurality of first traces and a plurality of second traces, of which the first one of the plurality of second traces is next to the last one of the plurality of first traces, the sensing method comprising the steps of:
 (A) scanning the plurality of first traces by a first touch integrated circuit and the plurality of second traces by a second touch integrated circuit, the last one of the plurality of first traces providing a first ADC value; and   (B) producing a second ADC value from the first ADC value as a sensed value for the last one of the plurality of first traces, wherein the second ADC value is a function of the first ADC value.   
     
     
         5 . The sensing method of  claim 4 , wherein the step B comprises multiplying the first ADC value by two to produce the second ADC value. 
     
     
         6 . A sensing method for a capacitive touch system including a touch panel having a plurality of traces, the sensing method comprising the steps of:
 scanning the plurality of traces by a plurality of touch integrated circuits, each of the plurality of touch integrated circuits scanning only a respective portion of the plurality of traces, wherein each of the plurality of touch integrated circuits each time selects only one trace to charge thereto and discharge therefrom, in order to obtain an ADC value; and   determining a sensed value for each of the plurality of traces, wherein for each trace the sensed value is determined by the ADC value of the trace itself.