Patent ID: 9710114
Date: 2017-07-18
CPC Classifications: G06F,G09G

Claim:
1. A touch detection device that detects occurrence of a touch capacitance by an approach of a bodily finger or a touch input instrument such as a conductor similar to the bodily finger, the touch detection device comprising: a plurality of touch pads that form at least one of touch capacitances between the touch input instrument and the touch pads: a driving capacitor which has one side connected to the touch pads and to another side of which a driving voltage for detection of a touch input is applied; a charging unit for applying a pre-charging voltage to the touch pads; a driving voltage generator that generates the driving voltage periodically according to a set value; and a touch detector that is connected to some of the touch pads, and that detects a touch signal by using a driving back phenomenon when a touch capacitance is added to the driving capacitor according to occurrence or non-occurrence of a touch input in the touch input instrument, wherein the other ones of the touch pads that do not detect any touch input are connected to a predetermined voltage after the touch detector has completed a touch sensing operation, and the predetermined voltage is a ground (GND) or a DC voltage of a predetermined size, and wherein the voltage detected in the touch detector at the non-occurrence of the touch input is determined by Equation 1, the voltage detected by the touch detector when the touch capacitance is added is determined by Equation 2, and the driving back phenomenon is caused by a difference between Equations 1 and 2, in which Vpre is a pre-charging voltage charged by the charging unit, ΔVsensor is the voltage detected by the touch detector, Vh is a high level voltage applied to the driving capacitor, Vl is a low level voltage applied to the driving capacitor, Cdrv is a driving capacitance, Cvcom is a common electrode capacitance, Cp is a parasitic capacitance, and Ct is the touch capacitance.