Control circuit and method of capacitance type touch board

Abstract

The invention relates to a control circuit of a capacitance type touch board, which is provided with a plurality of induction lines. The control circuit is characterized by comprising an empty induction line, a multiplexer, a first sensing circuit, a second sensing circuit and a computing circuit, wherein the empty induction line is arranged adjacent to the plurality of induction lines; the multiplexer is connected with the plurality of induction lines; the first sensing circuit is connected with the multiplexer and used for sensing and converting the capacitance value variable quantities of the plurality of induction lines into first signals; the second sensing circuit is connected with the empty induction line and used for sensing and converting the capacitance value variable quantity of the empty induction line into a second signal; and the computing circuit is connected with the first sensing circuit and the second sensing circuit and used for filtering out noise components in the first signals according to the second signal and generating outputting signals at an output end. The control circuit and the method of the capacitance type touch board have the advantage of improving noise influences.

Description

technical field [0001] The invention relates to a capacitive touch panel, in particular to a control circuit and method of the capacitive touch panel which can improve the influence of noise. Background technique [0002] figure 1 It is a schematic diagram of a known capacitive touch panel. There are multiple sensing lines on the touch panel 10 connected to the sampling circuit 14 via the multiplexer 12, and the analog-to-digital converter 16 detects when an object touches the touch panel 10. The change in capacitance value caused by the sensing line is converted into a digital sensing signal d(n) for subsequent calculations, where n is a time variable. The signal of the sensing line is susceptible to environmental noise (noise), and the environmental noise (noise) is sampled by the sampling circuit 14 together with the inductance (signal) caused by the contact of the object, and then converted by the analog-to-digital converter 16, mixed in the sensing signal In d(n), it ...

AI Technical Summary

Problems solved by technology

The signal of the sensing line is susceptible to environmental noise (noise), and the environmental noise (noise) is sampled by the sampling circuit 14 together with the inductance (signal) caused by the contact of the object, and then converted by the analog-to-digital converter 16, mixed in the sensing signal In d(n), it is easy to cause misjudgment of the touchpad

[0003] Existing anti-noise methods used in capacitive touch panels include setting a shielding layer (shielding), filtering out noise with a digital filter with a fixed coefficient, and suspending signal extraction when noise occurs, etc., but these methods have costs High, poor operating performance, or only against specific noises

[0004] Therefore, there are above-mentioned inconveniences and problems in the anti-noise method of the known capacitive touch panel.

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