Touch Panel Control Circuit Noise Suppression via Synchronized Integration

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Solution Overview

Problem

Existing touch panel control circuits face challenges in effectively suppressing noise in severe environments, such as those with commercial power supply variations and electromagnetic interference, which affect the accuracy of touch detection.

Innovation Solution

A touch panel control circuit that includes a drive circuit to apply pulses to Y electrodes and a detection circuit with switched capacitor circuits and integration circuits, operating in synchronization to function as a switched capacitor filter, enhancing noise suppression by filtering signal charges multiple times in synchronization with the pulses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single integration circuit is used for touch detection, then the device complexity is low, but the noise suppression capability is insufficient in severe environments

Engineering Contradiction:

Improvenoise suppression capabilityVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The detection circuit is segmented into multiple integration circuits (first integration circuit and second integration circuit) that operate in parallel. Each integration circuit processes signal charges independently by integrating them a different number of times, allowing for enhanced noise suppression through multiple integration stages while maintaining modular circuit architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The drive circuit applies periodic pulse signals to the Y electrodes, and the detection circuit integrates signal charges multiple times in synchronization with these periodic pulses. This periodic integration action enhances noise suppression by filtering out non-synchronized noise components while accumulating valid touch signal charges across multiple integration cycles.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If multiple pulses are applied to Y electrodes within a predetermined period, then the signal level increases, but the detection precision may be affected by noise from display drive signals

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidnoise interference from display signals

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The detection circuit acts as an intermediary between the touch panel electrodes and the processing circuitry. It includes switched capacitor circuits that selectively capture and integrate signal charges from the electrodes, filtering out noise from display drive signals through synchronized integration operations that distinguish touch signals from display noise based on their temporal characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The integration circuits provide feedback by accumulating signal charges over multiple pulse cycles and comparing the integrated values to detect touch events. The circuit uses the integrated signal levels to determine whether a touch has occurred, with the feedback mechanism enhancing detection precision by considering multiple pulse responses rather than relying on a single pulse measurement.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration achieves further improved noise suppression compared to traditional integration circuits, effectively reducing noise interference while maintaining signal integrity, particularly in severe environments.

Implementation Method 1

a first plurality of electrodes intersect a second plurality of electrodes to form a plurality of intersection capacitors

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

electric charges corresponding to a capacitance value of the intersection capacitor at that time are transmitted and are accumulatively added by an integration circuit

Methodology Applied

Scientific EffectElectrical charge accumulation: Electrical Accumulator

Data Source

PatentUS9437169B2Touch panel control circuit and semiconductor integrated circuit using the same

Publication Date: 2016.09.06 OMNIVISION TDDI ONTARIO LLP

AI summary

A touch panel control circuit includes a drive circuit that drives Y electrodes of a touch panel, and a detection circuit that is connected to X electrodes and detects a capacitance value of an intersection capacitor. The drive circuit applies a plurality of pulses to the Y electrodes in a predetermined period. The detection circuit includes a switched capacitor circuit capable of operating with respect to an input signal from the X electrodes in synchronization with the plurality of pulses, and an integration circuit that is connected to an output of the switched capacitor circuit and operates in synchronization with the pulses. The switched capacitor circuit is allowed to operate as a filter, and the switched capacitor circuit is set to have characteristics which have a maximum gain at a direct current and a frequency of a corresponding pulse and in which the gain is suppressed at a frequency therebetween.