LCD Common Electrode Merging Touch Sensing and Driving

Solution Overview

Problem

Existing liquid crystal display (LCD) devices with integrated touch screens face challenges such as increased manufacturing cost, complex manufacturing processes, and decreased total thickness due to the additional touch screen layer on the upper surface of the liquid crystal panel.

Innovation Solution

The proposed LCD device incorporates a common electrode block that functions as both a sensing electrode for touch input and an electric field driver for the liquid crystal, eliminating the need for an additional touch screen layer. This is achieved through the use of sensing lines electrically connected to the common electrode blocks, which are insulated from the remaining common electrode blocks when connected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an additional touch screen layer is provided on the upper surface of the liquid crystal panel, then touch sensing function is enabled, but the total thickness of the device increases

Engineering Contradiction:

Improvetouch sensing functionVSAvoidtotal thickness

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent merges the touch sensing function with the existing common electrode structure of the liquid crystal display. The common electrode is patterned to serve dual purposes: maintaining the liquid crystal electric field and functioning as a sensing electrode for touch input. This eliminates the need for a separate touch screen layer, thereby reducing device thickness while preserving touch sensing capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The common electrode is designed to perform multiple functions simultaneously: it maintains the liquid crystal display's electric field function and serves as a sensing electrode for touch input. By making the common electrode multi-functional, the patent eliminates the need for additional dedicated touch sensing layers, thus reducing overall device thickness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If an additional touch screen layer is provided on the upper surface of the liquid crystal panel, then touch sensing function is enabled, but manufacturing cost increases

Engineering Contradiction:

Improvetouch sensing functionVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent combines the touch sensing function with the existing common electrode manufacturing process. The common electrode is patterned during the standard LCD manufacturing process to serve as both the liquid crystal drive electrode and the touch sensing electrode. This integration eliminates the need for separate touch screen manufacturing steps, reducing overall manufacturing cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The common electrode is designed to perform multiple functions simultaneously: it maintains the liquid crystal display's electric field function and serves as a sensing electrode for touch input. By making the common electrode multi-functional, the patent eliminates the need for additional dedicated touch sensing layers, thus reducing manufacturing cost.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If an additional touch screen layer is provided on the upper surface of the liquid crystal panel, then touch sensing function is enabled, but the manufacturing process becomes complex

Engineering Contradiction:

Improvetouch sensing functionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the touch sensing function with the existing common electrode structure of the liquid crystal display. The common electrode is patterned to serve dual purposes: maintaining the liquid crystal electric field and functioning as a sensing electrode for touch input. This eliminates the need for a separate touch screen layer, thereby simplifying the manufacturing process.

Inventive Principle:

Principle #5Merging (Combining)

4Measurement precision

If sensing lines are electrically connected to all common electrode blocks, then touch sensing coverage is maximized, but electrical interference between blocks increases

Engineering Contradiction:

Improvetouch sensing coverageVSAvoidelectrical interference

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent divides the common electrode into multiple isolated common electrode blocks that are electrically independent from each other. Each block can be independently connected to sensing lines, allowing selective activation. This segmentation prevents electrical interference between adjacent blocks while maintaining comprehensive touch sensing coverage through coordinated operation of multiple blocks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different electrical connection configurations to different regions of the display. Each common electrode block can be independently connected or disconnected from sensing lines based on local requirements. This allows the system to maximize touch sensing coverage in active regions while minimizing electrical interference by isolating blocks that are not currently needed for sensing.

Inventive Principle:

Principle #3Local quality

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 simplifies the device structure, reduces manufacturing costs, and maintains the device's thickness while enabling effective touch sensing on the X-Y coordinates plane using sensing lines formed in only one direction.

Implementation Method 1

the common electrode blocks, together with the pixel electrode, forms an electric field

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

If a user touches a predetermined position, a capacitance between the first sensing electrode 24 and the second sensing electrode 26 is changed at the touched position

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS20250093695A1Display device

Publication Date: 2025.03.20 LG DISPLAY CO LTD

AI summary

A display device may include: a first data line electrically connected to a first thin film transistor; a first pixel electrode electrically connected with the first thin film transistor; a second data line electrically connected to a second thin film transistor; a second pixel electrode electrically connected with the second thin film transistor; a first touch sensing electrode corresponding to the first pixel electrode and insulated from the first pixel electrode; a second touch sensing electrode corresponding to the second pixel electrode and insulated from the second pixel electrode; a first sensing line electrically connected with the first touch sensing electrode; and a second sensing line electrically connected with the second touch sensing electrode, wherein the first data line overlaps with the first touch sensing electrode and the second touch sensing electrode, and the second data line overlaps with the first touch sensing electrode and the second touch sensing electrode.