| 摘要 |
<p>A capacitance measuring apparatus is provided, for example for measuring variations in pixel capacitance of an active matrix liquid crystal display to provide a "touch screen" function. The apparatus comprises a capacitor network having a plurality of states presenting different capacitances. A sense amplifier compares a capacitance to be measured with the capacitance of the network and a comparator supplies an output indicating whether the capacitance to be measured is larger or smaller than the capacitance of the network. A control circuit causes the network to switch through its states and monitors the output of the comparator so as to select the state of the network presenting a capacitance adjacent the capacitance to be measured. The digital measurement corresponding to the capacitance presented by the network is supplied to an output and provides a measure of the capacitance to be measured.</p> |
