Dummy Pixel Deterioration Measurement for OLED Brightness Uniformity

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Solution Overview

Problem

OLED display devices with regions of varying pixel densities face challenges in maintaining image quality due to faster deterioration of pixels in low-density regions, making accurate brightness adjustment difficult, especially as deterioration progresses.

Innovation Solution

Incorporating dummy pixels outside the display region, associated with low-density pixels, which are used to measure deterioration and feed back results for adjusting the brightness of the associated pixels, while being covered by light-blocking films to prevent visibility and interference with image display.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If dummy pixels are added outside the display region to measure deterioration, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvedeterioration measurement accuracyVSAvoidpixel structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The pixel array is segmented into display pixels within the display region and dummy pixels outside the display region. Each dummy pixel is associated with specific display pixels in the low-density region, allowing separate measurement of deterioration without interfering with the display function. This segmentation enables independent deterioration monitoring while maintaining display quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Dummy pixels serve as intermediary elements that indirectly measure the deterioration of display pixels. Since dummy pixels are positioned outside the display region and covered by light-blocking films, they act as proxies that capture deterioration characteristics without directly affecting the displayed image, thus enabling measurement while preserving display integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If light-blocking films are applied to dummy pixels to prevent visibility, then image quality is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveimage display qualityVSAvoidfabrication process complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Light-blocking films are applied selectively only to the dummy pixels located outside the display region, rather than covering the entire pixel array. This localized application ensures that the dummy pixels remain invisible during normal operation while minimizing the impact on manufacturing processes. The light-blocking property is applied only where necessary to prevent interference with the displayed image.

Inventive Principle:

Principle #3Local quality

3Illumination intensity

If higher driving current is supplied to low-density region pixels to compensate for lower pixel density, then brightness uniformity is improved, but pixel deterioration accelerates

Engineering Contradiction:

Improvebrightness uniformityVSAvoidpixel lifespan

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The deterioration measurement using dummy pixels is performed in advance and continuously monitored before significant image quality degradation occurs. By detecting deterioration trends early through the dummy pixels, the system can predict when display pixels will require compensation or replacement, allowing proactive maintenance rather than waiting for visible degradation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit uses feedback from dummy pixel measurements to monitor and assess the deterioration state of associated display pixels. Although the feedback mechanism primarily enables measurement, the data obtained provides insight into deterioration rates, allowing for potential adjustments in driving current strategies to balance brightness uniformity with pixel lifespan management.

Inventive Principle:

Principle #23Feedback

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 configuration allows for accurate estimation and compensation of pixel deterioration in low-density regions, maintaining display quality by ensuring appropriate brightness adjustments without affecting image display.

Implementation Method 1

Each of the plurality of display pixel and the plurality of dummy pixels includes a light-emitting element that emits light in response to driving current

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

one or more light blocking films covering the plurality of dummy pixels on the side to be viewed

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS11798446B2Display device and terminal device

Publication Date: 2023.10.24 WUHAN TIANMA MICRO ELECTRONICS CO LTD

AI summary

A display device includes a display region including display pixels, dummy pixels disposed outside the display region, light blocking films covering the dummy pixels. The display region includes a first region and a second region having a lower display pixel density than the first region. A control circuit is configured to supply the display pixels in the second region with driving current higher than driving current for the first region for the same grayscale level specified in image data, supply each of the dummy pixels with the same data signal as a data signal for the associated display pixel in the second region, measure deterioration of the light-emitting element of each of the dummy pixels, and adjust data signals for the display pixels in the second region associated with the dummy pixels based on results of the measurement.