OLED Gray-Scale Data Inversion for Uniform Light Emission

Solution Overview

Problem

Existing light-emitting devices with multiple OLED elements face variations in light emission characteristics over time, leading to luminance irregularities, particularly when producing multiple images with the same shape, which requires increased storage capacity to maintain uniform emission counts, resulting in larger circuit sizes and higher manufacturing costs.

Innovation Solution

A light-emitting device configuration that includes a storage unit for first gray-scale data, a data processing unit to generate second gray-scale data with inverted high and low levels, and a driving unit to control light emission in separate periods based on both data sets, ensuring uniform light emission across elements and reducing storage capacity needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mass storage device is used to hold the number of times of light-emission for each light-emitting element, then variation in characteristic can be suppressed, but circuit size becomes large and manufacturing costs increase

Engineering Contradiction:

Improveuniformity of light-emission characteristicVSAvoidcircuit size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential information needed for compensation (gray-scale data representing light-emission counts) from the full storage requirement, storing it in a simplified storage unit rather than using a complete mass storage device. This reduces circuit size while maintaining the ability to suppress characteristic variation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the storage approach from storing detailed light-emission count data to storing compressed gray-scale data that represents the essential compensation information. This parameter change in data representation reduces storage capacity requirements while maintaining compensation effectiveness.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If mass storage device is used to hold the number of times of light-emission for each light-emitting element, then variation in characteristic can be suppressed, but manufacturing costs increase

Engineering Contradiction:

Improveuniformity of light-emission characteristicVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts only the essential information needed for compensation (gray-scale data representing light-emission counts) from the full storage requirement, storing it in a simplified storage unit rather than using a complete mass storage device. This reduces circuit size while maintaining the ability to suppress characteristic variation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive mass storage devices with simpler, cheaper storage units that hold only the minimum necessary gray-scale data for compensation. This substitution reduces manufacturing costs while maintaining the essential function of suppressing light-emission variation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Manufacturing precision

If high-definition image with more light-emitting elements is used, then image quality is improved, but storage capacity requirement increases

Engineering Contradiction:

Improveimage definitionVSAvoidstorage capacity

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent changes the storage approach from storing detailed light-emission count data to storing compressed gray-scale data that represents the essential compensation information. This parameter change in data representation reduces storage capacity requirements while maintaining compensation effectiveness for high-definition images.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of storing the actual light-emission count data and using it directly, the patent inverts the approach by storing gray-scale data that represents the compensation needed, and then applying this inverted data to achieve uniform light emission across all elements.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS7944459B2Light-emitting device, driving circuit, driving method, electronic apparatus, and image forming apparatus

Publication Date: 2011.05.17 ELEMENT CAPITAL COMMERCIAL CO PTE LTD

AI summary

A light-emitting device includes a plurality of light-emitting elements, each emitting light with a light amount according to a driving signal, a storage unit that stores first gray-scale data for assigning a gray-scale value of each of the plurality of light-emitting elements, a data processing unit that generates second gray-scale data from the first gray-scale data stored in the storage unit for each light-emitting element such that, as the gray-scale value assigned by the first gray-scale data is large, a gray-scale value assigned by the second gray-scale data is made small, and a driving unit that causes the individual light-emitting elements to emit light in a first period upon supply of a driving signal according to the first gray-scale data stored in the storage unit, and causes the individual light-emitting elements to emit light in a second period different from the first period upon supply of a driving signal according to the second gray-scale data generated by the data processing unit.