Self-capacitance touch sensing device capable of reducing substrate capacitance

Abstract

The invention provides a self-capacitance touch sensing device capable of reducing substrate capacitance. The self-capacitance touch sensing device capable of reducing the substrate capacitance comprises a self-capacitance touch screen and a signal processing module. The signal processing module comprises an integrated operational amplifier, a feedback capacitor, a substrate capacitor and a controlled switch. The reverse-phase input end of the integrated operational amplifier is electrically connected with a channel capacitor. By the adoption of the self-capacitance touch sensing device capable of reducing the substrate capacitance, in the pre-discharge stage, the channel capacitor is made to discharge electricity, and at least one of the substrate capacitor and the feedback capacitor is charged; in the sensing stage, the channel capacitor is charged, and the charge variable quantity, caused by touch, of a branch where the channel capacitor is located is output from the output end of the integrated operational amplifier. According to the self-capacitance touch sensing device capable of reducing the substrate capacitance, the charge mode of the substrate capacitor is changed through pre-storing of electric charge on the feedback capacitor, the quantity of electric charge which can be provided by the substrate capacitor is increased, and then the substrate capacitance is reduced; in this way, the area of a chip is reduced, process cost is reduced, and the self-capacitance touch sensing device can be lighter and thinner.

Description

technical field [0001] The invention relates to a circuit for signal processing of collected signals, in particular to a circuit for signal processing of charge variation signals collected by a touch screen. Background technique [0002] Prior art only capacitive touch sensing devices, such as Figure 5 As shown, it includes a self-capacitance touch screen 4 for collecting touch information that causes capacitance changes and a signal processing circuit 3 for detecting capacitance changes. The capacitance formed by the self-capacitance touch screen 4 due to the electrodes provided is C S Each channel capacitance 41. The prior art signal processing circuit 3 includes an integrated operational amplifier 34, and the capacitance electrically connected between the inverting input terminal and the output terminal of the integrated operational amplifier 34 is C f A feedback capacitor 32, and a substrate capacitor 31 with a capacitance of Cb whose one end is electrically connected...

AI Technical Summary

Problems solved by technology

It can be known from formula (1) that when the channel capacitance C S When increasing, C b It will also increase accordingly, which will lead to an increase in chip area, which not only increases the process cost, but also affects the development of self-capacitive touch sensing devices in the direction of thinning and lightening

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