Gamma Correction Circuit Adjusting Common Voltage Levels

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing gamma correction methods for LCDs face challenges such as increased fabrication costs, surface roughness issues, lateral electric field disturbances, and reduced color resolution due to mechanical adjustments in LC layer thickness and complex digital signal compensation circuits.

Innovation Solution

A gamma correction apparatus comprising a digital to analog converter, compensating circuits, and adjusting circuits that provide three adjustable common voltage levels to adjust the transparency of the LC layer and correct RGB gamma curves without mechanical design changes, simplifying the circuit layout and reducing the number of adjustable levels needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If different thicknesses are assigned to transparency organic layers in RGB pixel devices to adjust LC layer thickness, then RGB gamma curves can achieve better coherence, but fabrication cost increases and surface roughness problems occur

Engineering Contradiction:

Improvegamma curve coherenceVSAvoidfabrication cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical/physical adjustment methods (varying organic layer thickness) with an electrical signal processing approach. A gamma correction circuit processes digital signals before they reach the pixel devices, using voltage level adjustment to correct gamma curve separation without physical structural changes to the LCD panels.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the electrical parameters (voltage levels) of the driving signals to correct gamma curve separation. By adjusting the voltage levels applied to RGB pixel devices through signal processing, the system achieves gamma correction without modifying physical parameters like layer thickness.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If different thicknesses are assigned to transparency organic layers, then RGB gamma curves can be adjusted, but lateral electric fields are generated between neighboring pixel electrodes

Engineering Contradiction:

Improvegamma curve adjustmentVSAvoidlateral electric field disturbance

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent eliminates the mechanical/physical source of lateral electric fields by avoiding thickness variations in organic layers. Instead, it uses electrical signal processing to achieve gamma correction, thereby preventing the generation of harmful lateral electric fields between neighboring pixel electrodes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If complex digital signal compensation circuits are used to correct gamma curves, then color accuracy can be improved, but device complexity and number of adjustable levels increase

Engineering Contradiction:

Improvecolor accuracyVSAvoidcircuit complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses parameter changes in voltage levels through a relatively simple gamma correction circuit to achieve gamma curve correction. By adjusting voltage levels in a controlled manner, the system corrects color accuracy without requiring complex digital signal compensation circuits with multiple adjustable levels.

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

This solution effectively corrects RGB gamma curve separation by adjusting analog signals and common voltage levels, reducing fabrication costs and maintaining color accuracy without sacrificing displaying signal levels, thus improving color correctness and simplifying the LC driving circuit design.

Implementation Method 1

a liquid crystal (LC) driving circuit is usually used in an LCD to decode input signals so as to form displaying data and scanning data, and further to control the displaying of the LCD

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Implementation Method 2

The upper substrate 100 has a color filter layer 110 formed on a lower surface thereof to let the pixel device shows a preset color

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS7649541B2Gamma correction apparatus and a method of the same

Publication Date: 2010.01.19 AU OPTRONICS CORP

AI summary

A gamma correction apparatus comprising a digital to analog converter (DAC), a plurality of compensating circuits, and at least one adjusting circuit is provided. The DAC is used to receive RGB digital signals to further generate analog signals. The analog signals are then transferred to the relative pixel devices through the signal lines on the LCD panel. The compensating circuits inserted between the DAC and the signal lines are used to adjust the analog signals to correct the displaying brightness of the pixel devices. The adjusting circuit connecting to the compensating circuits is used to control the operation of the compensation circuits. In addition, a method for adjusting gamma curves by providing three common voltage levels related to RGB colors individually is also provided to achieve better white balance.