LCD Column Inversion via 2-Column Demultiplexers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Liquid crystal displays (LCDs) face issues with liquid crystal biasing due to consistent voltage polarity, leading to altered light transmission characteristics, and existing inversion schemes like dot and column inversion increase power consumption and introduce crosstalk, while color reproduction variations across devices affect the white point consistency.

Innovation Solution

Implementing a 2-column demultiplexer system in LCDs to perform column inversion, where columns of pixels are programmed with frames of image data, reducing polarity switches and enhancing pixel transmittance by varying the spacing between columns driven at opposite polarities, and adjusting the white point through selective column inversion schemes and duty ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If column inversion is implemented to prevent liquid crystal biasing, then liquid crystal biasing is reduced, but power consumption increases

Engineering Contradiction:

Improveliquid crystal biasing preventionVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The display panel is divided into superpixels containing multiple pixel columns, with demultiplexers selectively driving specific columns at inverted polarities. This segmented approach applies inversion only where needed to prevent biasing rather than inverting entire frames or all columns, thereby reducing overall power consumption while maintaining biasing prevention effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions (superpixels) of the display are treated differently through selective column inversion. Some columns within superpixels are driven at inverted polarities while others maintain normal polarity, creating local quality variations that prevent biasing in specific areas without requiring global inversion, thus optimizing power usage.

Inventive Principle:

Principle #3Local quality

2Reliability

If dot inversion is used to prevent liquid crystal biasing, then liquid crystal biasing is prevented, but circuitry complexity increases significantly

Engineering Contradiction:

Improveliquid crystal biasing preventionVSAvoiddriving circuitry complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple pixel columns within superpixels are merged into groups that share common demultiplexer control. Instead of independently controlling each pixel column as in dot inversion, the patent combines columns into superpixel structures with shared driving circuitry, significantly reducing the complexity of the driving circuitry while maintaining biasing prevention.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The demultiplexers are designed to universally drive multiple columns within superpixels using a single inverted polarity signal. This multi-functional approach allows one demultiplexer to control several columns, reducing the total number of independent circuit elements needed compared to pixel-level dot inversion control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If columns driven at opposite polarities are placed adjacent to each other, then column inversion can be implemented, but crosstalk between neighboring pixels increases

Engineering Contradiction:

Improveinversion scheme implementationVSAvoidcrosstalk between pixels

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

Columns driven at opposite polarities are extracted from adjacent positions and relocated to non-adjacent positions within the superpixel structure. By taking out the harmful adjacent opposite-polarity column arrangement and replacing it with spaced-apart columns, the crosstalk between neighboring pixels is minimized while maintaining the column inversion functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The superpixel structure employs asymmetric column arrangements where columns at inverted polarities are deliberately positioned at different spatial locations rather than symmetrically adjacent to each other. This asymmetric spacing reduces the electromagnetic coupling and crosstalk between pixels driven at opposite polarities while preserving the biasing prevention benefits.

Inventive Principle:

Principle #4Asymmetry

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 approach reduces power consumption, minimizes crosstalk, and achieves consistent color reproduction across devices by optimizing pixel transmittance and white point adjustment, enhancing the overall performance and reliability of LCDs.

Implementation Method 1

Pixels may be driven with particular voltages, causing the liquid crystal material to change orientation, thereby varying the amount of light passing through the pixel

Methodology Applied

Scientific EffectLiquid crystal orientation change: Liquid Crystals

Data Source

PatentUS9047832B2Systems and methods for liquid crystal display column inversion using 2-column demultiplexers

Publication Date: 2015.06.02 APPLE INC

AI summary

Systems, methods, and devices for performing column inversion using 2-column demultiplexers are provided. In one example, an electronic display may include a display panel with columns of pixels configured to be programmed with frames of image data and display driver circuitry. The display driver circuitry may include three demultiplexers, each respectively coupled to one pixel column of a first superpixel and one pixel column of a second superpixel. Each of the three demultiplexers may receive amplified image data of a single polarity per frame.