Patent ID: 8773147
Filing Date: 2014-07-08
Classification: G06F

Abstract:
1. A capacitive touch sensing device by detecting induced electric field, comprising: a differential amplifier having a first input end, a second input end and an output end; a resistor having two ends electrically connected to the first input end and the second input end of the differential amplifier, respectively; and a signal judgment circuit electrically connected to the output end of the differential amplifier, wherein the first input end of the differential amplifier is electrically connected to a touch sensor, the second input end of the differential amplifier is connected to circuit ground, and as the touch sensor receives an induced electric field signal, the induced electric field signal is amplified by the differential amplifier and the induced electric field signal after amplification is then determined by the signal judgment circuit, wherein the signal judgment circuit includes: zero potential triggering circuit electrically connected to the output end of the differential amplifier, in which as the amplified induced electric field signal is at a zero potential, the zero potential triggering circuit generates a triggering signal; a delay circuit electrically connected to the zero potential triggering circuit for correspondingly receiving the triggering signal and delaying the triggering signal a period of time for output; and a comparator electrically connected to the delay circuit to compare the amplified induced electric field signal with a reference voltage upon receiving the delayed triggering signal from the delay circuit, in which if the amplified induced electric field signal is larger than the reference voltage, it outputs a signal.