OLED Brightness Control via Adaptive Gamma Adjustment

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Solution Overview

Problem

Organic electroluminescence display devices face challenges in adjusting brightness without fluctuating gamma values, as they lack a separate light emitting unit like backlights in liquid crystal displays, making it difficult to maintain consistent image gamma across varying duty ratios of light-emitting control signals.

Innovation Solution

A brightness control unit is introduced to adjust the duty ratio of light-emitting control signals and set gamma values based on a brightness mode, using a lookup table or gamma function to convert image data and maintain constant gamma, regardless of changes in duty ratios, ensuring consistent image brightness and gamma across different brightness modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the duty ratio of light-emitting control signals is adjusted to control brightness, then brightness is changed, but gamma values fluctuate

Engineering Contradiction:

ImprovebrightnessVSAvoidgamma value consistency

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the gamma value parameter in response to duty ratio changes. The gamma value is not fixed but varies according to the duty ratio of light-emitting control signals, ensuring that brightness can be controlled while maintaining consistent image gamma. This resolves the contradiction by making the gamma parameter adaptive rather than static.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by monitoring the duty ratio of light-emitting control signals and using this information to adjust the gamma value accordingly. This closed-loop approach ensures that any changes in duty ratio are compensated by corresponding gamma adjustments, maintaining consistent image quality while achieving brightness control.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If a separate light emitting unit like backlight is used, then brightness control is easier, but device complexity increases

Engineering Contradiction:

Improvebrightness controlVSAvoiddevice structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies self-service by enabling the organic electroluminescence display device to control its own brightness through software-based gamma adjustment rather than requiring a separate physical light emitting unit. The device uses its existing light-emitting pixels and controls brightness by adjusting the gamma value in response to duty ratio changes, eliminating the need for additional backlight components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical/optical system of a separate backlight unit with an electronic/software-based gamma adjustment system. Instead of using a physical light emitting unit for brightness control, the invention uses signal processing and parameter adjustment (gamma correction) to achieve the same function, thereby reducing device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9460657B2Display device and method of driving the same

Publication Date: 2016.10.04 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a pixel unit including a plurality of pixels that have light-emitting time periods adjusted in response to light-emitting control signals, and a brightness control unit that adjusts a duty ratio of the light-emitting control signals and setting gamma and that converts image data according to a brightness mode.