Patent ID: 9448664
Filing Date: 2016-09-20
CPC Classification: G06F

Claim Text:
1. A capacitive touch detection apparatus, comprising: at least one sensor pad to output a signal based on a touch state in response to an alternating voltage in a floating state after being charged with an electric charge; an operational amplifier including a first input connected to an output of the at least one sensor pad and a second input to receive the alternating voltage; a level shift detection unit to detect a touch signal based on a difference between a voltage variation at an output end of the operational amplifier caused by the alternating voltage and a voltage variation at the output end of the operational amplifier caused by occurrence of a touch; and a switching unit including a first switch to control an electric potential between a first input end and the output end of the operational amplifier and a second switch to connect or disconnect the sensor pad and the first input of the operational amplifier, wherein the first switch and the second switch are switched on alternately so that the difference between the voltage variations has linearity with a touch capacitance.