Self-capacitance touch detection circuit

Abstract

The invention discloses a self-capacitance touch detection circuit which comprises a signal generator, a first amplifier, an offset signal generator and an analog-digital converter. The signal generator generates drive signals and is then divided into a first output branch and a second output branch, wherein the first output branch is connected with the offset signal generator. Signals passing through an offset circuit are output to a first input end of the amplifier. The second output branch is connected with a touch panel and a second input end of the amplifier respectively. The amplifier outputs signals to the analog-digital converter which converts the signals into digital signals to be sent to a main controller. According to the self-capacitance touch detection circuit, through additional arrangement of the offset signal generator between the signal generator and the amplifier, the amplification times of the amplifier are increased, and the anti-interference capability of the detection circuit is improved.

Description

technical field [0001] The invention belongs to the technical field of circuits, in particular to a self-capacitance touch detection circuit for a capacitive touch screen. Background technique [0002] The existing capacitive touch screen / key mainly adopts two technologies of self-capacitance detection touch input and mutual capacitance detection touch input. Self-capacitance detection technology is to ground one end of the capacitor, and send and receive signals from the other end of the capacitor to detect changes in capacitance to identify whether there is a touch input. Only one IO port is needed to detect the change of a single self-capacitance, occupying less IO ports. At the same time, this type of touch screen can be produced with a single layer of conductive material, which greatly saves the production cost of the screen. Mutual capacitance detection technology is to transmit a signal at one end of the capacitor, and receive a signal from the other end of the capa...

AI Technical Summary

Problems solved by technology

These self-capacitance detection methods have a common defect, that is, the ability to resist environmental interference is very weak

Especially for the touch display screen applied on the mobile phone, in the face of the interference from the LCD display and the interference from the radio frequency signal of the mobile phone, the signal-to-noise ratio of the touch signal realized by the existing self-capacitance detection method is not high, and most of them are in the Below 30:1, it will lead to the low resolution of the touch screen, and the touch detection is easy to be misoperated.

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