Integratable circuit achieving touch capacitor sensing through electric charge sharing

Abstract

The invention discloses an integratable circuit achieving touch capacitor sensing through electric charge sharing. The integratable circuit comprises an electric charge sharing circuit, a voltage-controlled oscillator, a reference frequency generator, a switch clock generator and a frequency comparator circuit. The electric charge sharing circuit further comprises a sensing capacitor, a touch capacitor, an electric charge sharing capacitor, a charging switch, an electric charge sharing switch and a discharging switch, and electric charges of the charged sensing capacitor are shared with the discharged sharing capacitor so that voltage can be accumulated on the sharing capacitor; the sharing capacitor is designed into the mode that the capacitance value is adjustable so that sensing capacitance values can be generated for different touch applications, and thus the proper sharing capacitance value can be adjusted. The charging switch, the discharging switch and the electric charge sharing switch are controlled through non-overlapping clock rates, the closing time of the charging switch is prolonged, and the closing time of the electric charge sharing switch and the closing time of the discharging switch are reduced to the maximum so that the interference of external environment background noise can be reduced.

Description

technical field [0001] The present invention relates to a touch capacitance sensing circuit, in particular to an integratable circuit for realizing touch capacitance sensing by charge sharing. Background technique [0002] With the popularization of various 3C products, the demand for touch panels is also increasing. In general, touch panels can be roughly classified into resistive, capacitive, ultrasonic, or infrared based on sensing principles. At present, the touch panel technology with the lowest cost in the market is the resistive system, and the resistive system has the highest market share in the global touch panel market. The resistive system is a standard glass panel consisting of two upper and lower ITO conductive layers laminated; the two layers are separated by a spacer area, and current can flow between the two layers. When in use, the pressure is used to make the upper and lower sets of ITO conduction contact together, and the change of the electric field wil...

AI Technical Summary

Problems solved by technology

On the other hand, the disadvantage of this circuit is that the capacitance value of the capacitor Csum must be hundreds to thousands times of the capacitance value of the capacitor Cx (for example, a capacitance value of hundreds of pF to nF), so it cannot be integrated circuit

Another disadvantage is the method of charge transfer. The accumulation of the voltage value Vsum is not linear, but the relationship between the voltage value Vsum and the capacitance value of the capacitor Cx is exponential. In other words, It is also less linear to calculate the difference in the capacitance value of the capacitor Cx

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