Touch Sensing System Integrating IR and Capacitive Detection

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Solution Overview

Problem

Existing touch sensing systems require both IR type and mutual capacitive touch panels, increasing thickness and cost, and suffer from limited dynamic range in impedance measurement, leading to degraded touch detection capabilities.

Innovation Solution

A touch sensing system incorporating a touch screen with first and second driving electrodes, sensing electrodes, and detection circuits that utilize pulse and frequency sweep waveforms to detect user touch positions and recognize users through mutual capacitance and impedance changes, respectively, without the need for a separate RLC band cut filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If both IR type touch panel and mutual capacitive type touch panel are used for user touch position detection and user recognition, then detection functionality is improved, but thickness and cost increase

Engineering Contradiction:

Improvedetection functionalityVSAvoidthickness

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent combines IR type touch panel and mutual capacitive type touch panel into a single integrated touch sensing system. The touch screen includes both first driving electrodes with second driving electrodes for mutual capacitive sensing, and infrared transmitting/receiving units for IR touch detection, allowing both functions to coexist in one unified structure rather than as separate stacked panels.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The touch screen structure is designed to perform multiple functions simultaneously: it detects user touch positions through both mutual capacitance changes and infrared ray interruption, and recognizes users through impedance measurement. This multi-functional integration eliminates the need for separate dedicated panels for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If both IR type touch panel and mutual capacitive type touch panel are used for user touch position detection and user recognition, then detection functionality is improved, but cost increases

Engineering Contradiction:

Improvedetection functionalityVSAvoidcost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If RLC band cut filter is used for user recognition, then user recognition is achieved, but gain range (dynamic range) is narrow and detection capability is degraded

Engineering Contradiction:

Improveuser recognition capabilityVSAvoiddetection capability

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

Instead of using a band cut filter that blocks certain frequencies, the patent employs a band pass filter that selectively passes frequencies within a specific range. This inversion of the filtering approach widens the gain range and improves the dynamic range for impedance measurement, thereby enhancing user recognition capability and detection precision.

Inventive Principle:

Principle #13The other way round (Inversion)

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 solution reduces the thickness and cost of the touch sensing system while enhancing user recognition capabilities by using an RCL band pass filter with a wider gain range, improving detection accuracy and eliminating the need for multiple touch panels.

Implementation Method 1

a mutual capacitive type touch panel for a user recognition (or user ID)... At a user touch, an impedance of the RLC filter is measured to recognize a user

Methodology Applied

Scientific EffectMutual capacitance: Capacitance

Implementation Method 2

an inductor that is connected between the sensing electrodes and the second detection circuit in the second sensing period

Methodology Applied

Scientific EffectInductance: Inductor

Implementation Method 3

an RCL band pass filter with a wider gain range, improving detection accuracy

Methodology Applied

Scientific EffectRCL band pass filter: Filter (electronic)

Data Source

PatentUS10528179B2Touch sensing system and display device including the same

Publication Date: 2020.01.07 LG DISPLAY CO LTD

AI summary

The present disclosure provides a touch sensing system and a display device including the same. The touch sensing system includes: a touch screen that includes a plurality of first driving electrodes, a plurality of second driving electrodes, and a plurality of sensing electrodes; a first driving circuit that outputs a first driving signal of a pulse waveform to a respective first driving electrode of the plurality of first driving electrodes in a first sensing period; a second driving circuit that outputs a second driving signal of a frequency sweep waveform to a respective second driving electrode of the plurality of second driving electrodes in a second sensing period; a first detection circuit that detects a first sensing signal sensed by at least one of the sensing electrodes in the first sensing period; a second detection circuit that detects a second sensing signal sensed by at least one of the sensing electrodes in the second sensing period; and an inductor that is connected between the sensing electrodes and the second detection circuit in the second sensing period.