OLED Display Luminous Time Control for Current Overflow

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Solution Overview

Problem

Existing display devices face issues with current overflow into luminescence elements due to high luminance input, leading to inefficient luminous time control and potential damage.

Innovation Solution

A display device with a luminescence element and pixel circuit configuration that includes an average luminance calculator and a luminous time setter, using a look-up table to regulate the effective duty for each frame period, ensuring the luminescence amount matches the preset reference duty and maximum luminance, thereby preventing current overflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the luminous time is shortened to lower the signal level for high average luminance, then the current overflow problem is partially addressed, but the luminescence amount becomes insufficient for extremely high luminance inputs

Engineering Contradiction:

Improveprevention of current overflowVSAvoidluminescence amount

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent changes the parameter of effective duty based on the average luminance of the picture signal. When average luminance is high, the effective duty is reduced to prevent current overflow; when average luminance is low, the effective duty is increased to maintain adequate luminescence amount. This dynamic parameter adjustment resolves the contradiction between preventing current overflow and maintaining sufficient luminescence.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a fixed reference duty is used for luminous time control, then the control method is simple, but it cannot adapt to varying average luminance levels of different picture signals

Engineering Contradiction:

Improvecontrol method complexityVSAvoidadaptation to different luminance levels

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamics into the luminous time control by making the effective duty variable rather than fixed. The effective duty is dynamically adjusted according to the calculated average luminance of the input picture signal, allowing the system to adapt to different luminance levels while maintaining a relatively simple control structure based on lookup tables.

Inventive Principle:

Principle #15Dynamics

3Illumination intensity

If the luminous time is extended to increase luminescence amount, then image quality improves, but current overflow occurs in high luminance scenarios

Engineering Contradiction:

Improveluminescence amountVSAvoidcurrent overflow

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by differentiating the effective duty setting based on the local condition of average luminance. Different parts of the luminance range (low, medium, high) receive different effective duty values, allowing the system to optimize luminescence amount for each luminance condition while preventing current overflow in high luminance scenarios.

Inventive Principle:

Principle #3Local quality

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

Precise control of luminescent time within each frame period prevents current overflow, maintaining optimal luminance and image quality while extending the lifespan of luminescence elements.

Implementation Method 1

organic EL displays (organic ElectroLuminescence displays, also called as OLED displays (Organic Light Emitting Diode displays))

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS8654044B2Display device, picture signal processing method, and program

Publication Date: 2014.02.18 MAGNOLIA BLUE CORP

AI summary

There is provided a display device including a display unit having pixels, each of which includes a luminescence element that individually becomes luminous depending on a current amount and a pixel circuit for controlling a current applied to the luminescence element according to a voltage signal, where the pixels are arranged in a matrix pattern. The display device includes an average luminance calculator (200) for calculating average luminance for a predetermined period of the input picture signal, and also includes a luminous time setter (202) for setting an effective duty depending on the calculated average luminance by the average luminance calculator (200), the effective duty regulating for each one frame a luminous time for which the luminescence element is luminous. The luminous time setter (202) sets the effective duty such that a luminescence amount regulated by a preset reference duty and possible maximum luminance of a picture signal.