Key-integrated LCD Panel Conductor Touch Detection

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Solution Overview

Problem

Conventional LCD panels with physical keys occupy space and increase weight and cost due to the need for printed circuit boards and flexible flat cables, limiting design freedom and user comfort in miniaturized electronic devices.

Innovation Solution

A key-integrated LCD panel design that incorporates a transistor substrate and a color filter substrate with conductors that form key districts when touched, using a controller to detect signal changes and generate key signals, reducing the number of physical keys and components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If conventional physical keys are used, then key input function is achieved, but device weight and overall cost increase due to printed circuit board and flexible flat cable requirements

Engineering Contradiction:
Improvedevice weightVSAvoidkey input function
Core Design Contradiction:
Weight of moving objectVSEase of operation

Solution Approach 1:

The patent merges the key input function with the LCD panel structure itself. Conductors are integrated directly into the LCD panel layers, eliminating the need for separate physical keys, printed circuit boards, and flexible flat cables. This consolidation reduces device weight while maintaining full key input functionality through touch-activated electrical contact between conductor layers.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the mechanical key system with an electrical field-based detection system. Instead of mechanical switches requiring physical contact and movement, the invention uses conductors arranged in specific patterns that detect touch input through changes in electrical contact or capacitance, thereby eliminating heavy mechanical components while preserving input functionality.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Length of stationary object

If conventional physical keys with printed circuit board and flexible flat cable are used, then key signal transmission is achieved, but device thickness and non-display area increase

Engineering Contradiction:
Improvedevice thicknessVSAvoidnumber of components
Core Design Contradiction:
Length of stationary objectVSDevice complexity

Solution Approach 1:

The patent combines multiple separate components (keys, printed circuit board, flexible flat cable) into a single integrated LCD panel structure. The conductors are embedded within the panel layers, allowing signal transmission to occur directly through the panel without requiring external circuit boards or cables, thereby reducing thickness and component count.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent transitions the key input system from a three-dimensional mechanical structure extending outside the panel to a two-dimensional planar conductor arrangement within the panel layers. This dimensional transformation allows key functionality to be achieved within the panel plane itself, reducing the need for additional thickness and external components.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If conventional physical keys are used, then reliable key input is achieved, but design freedom and customization flexibility are limited

Engineering Contradiction:
Improvedesign freedomVSAvoidkey input reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs dynamic conductor patterns that can be flexibly configured to create different key layouts and designs. The conductor arrangements can be adjusted and customized for different applications while maintaining reliable electrical contact for key input detection, providing both design freedom and functional reliability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent utilizes changes in electrical parameters (such as capacitance or resistance) when conductors come into contact or approach each other during touch input. This parameter-based detection method provides reliable key input recognition while allowing flexible configuration of conductor patterns to achieve various design requirements.

Inventive Principle:
Principle #35Parameter changes

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

Enables reduced non-display area, weight, and component count, allowing for easier customization and improved user interaction with virtual key images displayed on the LCD panel, enhancing design flexibility and user experience.

Implementation Method 1

When the key district is touched, the first and the second conductor electrically contact with each other, and the signal level at one of the first and the second conductor will change

Methodology Applied
Scientific EffectElectrical contact: Conduction (electrical)

Data Source

PatentEP2216707B1Key-integrated LCD panel and method of integrating keys into LCD panel
Publication Date: 2018.08.08 ACER INC
  • EP2216707B1 patent drawingFigure 1
  • EP2216707B1 patent drawingFigure 2
  • EP2216707B1 patent drawingFigure 3

AI summary

A keys-integrated LCD panel includes a first conductor arranged on one face of a transistor substrate and a second conductor arranged on one face of a color filter substrate facing toward the transistor substrate. The second conductor meets the first conductor without contacting with the first conductor, and a key district is formed at the position at where the second conductor meets the first conductor. When the key district is touched, the first and the second conductor electrically contact with each other and the signal level at one of the first and the second conductor will change. A controller is provided for detecting any change in the signal level at one of the first and the second conductor. When a change in the signal level is detected, the controller outputs a key signal corresponding to the touched key district.