Integrated Capacitive Touch Sensor in LCD Panel

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Solution Overview

Problem

Separate touch screen sensors increase the cost and weight of liquid crystal display units and may degrade the clarity and contrast of the display panel, as they are typically attached externally.

Innovation Solution

Integration of a touch screen sensor directly into the liquid crystal display panel, utilizing capacitive coupling between electrodes to detect touch locations, allowing for a single device to serve as both display and input without external attachments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a separate touch screen sensor is attached externally to the liquid crystal display panel, then the display provides both display and input functionality, but the cost and weight of the display unit increase

Engineering Contradiction:

Improvedisplay and input functionalityVSAvoiddisplay unit weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The patent combines the touch screen sensor functionality with the liquid crystal display panel by integrating transparent conductive films into the display structure itself. The front surface substrate and counter electrode substrate of the LCD panel are modified with conductive films that serve dual purposes: maintaining display functionality and enabling capacitive touch sensing, thereby eliminating the need for a separate external touch sensor assembly and reducing overall weight

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The liquid crystal display panel is designed to perform multiple functions simultaneously. The transparent conductive films deposited on the display substrates serve both as electrical electrodes for the liquid crystal operation and as sensing elements for touch detection. This multi-functionality allows the display unit to provide both visual output and touch input capabilities without requiring additional dedicated components

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If a separate touch screen sensor is attached externally to the liquid crystal display panel, then the display provides both display and input functionality, but the cost of the display unit increases

Engineering Contradiction:

Improvedisplay and input functionalityVSAvoiddisplay unit cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the manufacturing processes of the liquid crystal display panel and the touch sensor into a single integrated structure. The transparent conductive films are deposited during the display panel fabrication process using standard techniques such as sputtering or chemical vapor deposition, eliminating the need for separate touch sensor manufacturing and assembly operations, thereby reducing overall production costs

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The display panel components are designed to serve multiple functions. The transparent conductive films function both as liquid crystal control electrodes and as touch sensor elements, allowing a single manufacturing process to produce components that fulfill both display and input requirements, reducing the need for additional materials and assembly steps

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If a separate touch screen sensor is attached externally to the liquid crystal display panel, then the display provides both display and input functionality, but the clarity and contrast of the display panel are degraded

Engineering Contradiction:

Improvedisplay and input functionalityVSAvoiddisplay clarity and contrast

Core Design Contradiction:

Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent integrates the touch sensor layers within the existing display panel structure rather than attaching them externally. The transparent conductive films are incorporated into the substrate assembly, minimizing the addition of optical interfaces that could cause reflections or light scattering, thereby preserving display clarity and contrast while enabling touch functionality

Inventive Principle:

Principle #5Merging (Combining)

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 integration reduces costs and weight while maintaining display clarity and contrast by eliminating the need for external sensors and enhancing the display's functionality as both a screen and input device.

Implementation Method 1

utilizing capacitive coupling between electrodes to detect touch locations

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS8373667B2Flat panel display with capacitance sensing touch screen

Publication Date: 2013.02.12 MASSACHUSETTS INST OF TECH

AI summary

There is disclosed a display device with an integral touch screen. A display panel includes a plurality of pixels controlled by a plurality of column electrodes and a plurality of row electrodes. A column driver having a plurality of outputs drives the plurality of column electrodes, and a row driver having a plurality of outputs drives the plurality of row electrodes. A column sensor and a row sensor sense capacitive coupling between the row and column electrodes and a probe adjacent to an external surface of the display panel.