OLED Pixel Reference Circuit for Burn-In Deterioration Sensing
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Solution Overview
Problem
Organic light-emitting diode (OLED) elements suffer from irreversible brightness deterioration leading to issues like image burn-in, and existing methods struggle to accurately measure this deterioration due to variations caused by both temperature changes and actual degradation, requiring high-resolution measurement circuits.
Innovation Solution
A display device configuration that includes both display and dummy pixel circuits, where the dummy pixel circuit serves as a reference to measure the current-voltage characteristics of display pixel circuits, allowing for accurate evaluation of brightness deterioration by comparing these characteristics, thus enabling lower-resolution measurement circuits to differentiate between temperature-induced variations and actual degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution measurement circuits are used to accurately measure OLED brightness deterioration, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent introduces a reference pixel circuit as an intermediary element that experiences the same environmental conditions (temperature, humidity, aging) as the display pixels but is not driven for image display. This reference pixel serves as a mediator to capture environmental-induced characteristic changes, allowing the measurement circuit to compare display pixels against the reference rather than requiring absolute high-resolution measurements of each pixel's deterioration.
Solution Approach 2:
The reference pixel circuit is essentially a copy of the display pixel circuit structure, containing identical OLED elements and circuit components. This copying approach allows the system to replicate environmental effects on a separate element that can be used for comparison, reducing the need for complex high-resolution measurement of actual deterioration.
2Measurement precision
If environmental variations (temperature, humidity) are compensated for in OLED measurements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The reference pixel circuit acts as an intermediary that automatically captures environmental variations without requiring separate temperature sensors or humidity sensors. By comparing display pixels to this environmental reference, the system compensates for environmental effects through the comparison process itself, rather than through complex environmental sensing and calculation circuits.
Solution Approach 2:
The reference pixel circuit self-services by automatically experiencing and recording environmental effects on its OLED element. It requires no external control or adjustment - simply by being present in the same environmental conditions and not being driven for display, it naturally accumulates the same environmental-induced characteristic changes as the display pixels, providing automatic environmental compensation.
3Reliability
If reference pixel circuits are added to measure and compensate OLED deterioration, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The reference pixel circuit uses a copied structure identical to display pixels, containing the same OLED element type and circuit configuration. This copying ensures that any deterioration measured in the reference pixel accurately reflects what would occur in display pixels under the same conditions, improving reliability of the compensation without requiring fundamentally different or more complex reference circuit designs.
Solution Approach 2:
The patent maintains homogeneity between display pixels and reference pixels by using identical OLED element structures and circuit configurations. This homogeneity ensures that the reference pixel accurately represents the deterioration characteristics of display pixels, improving the reliability of compensation while avoiding the need for heterogeneous or specially-designed reference circuits that would increase complexity.
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 approach allows for precise estimation and adjustment of OLED element brightness, reducing brightness differences among pixels and mitigating image burn-in by accurately distinguishing between temperature-induced variations and genuine degradation, thereby enhancing display quality.
Implementation Method 1
An organic light-emitting diode (OLED) element is a current-driven light-emitting element
Data Source
AI summary
A display device includes a display pixel circuit including a display light-emitting element, a reference light-emitting element, and a display driving circuit. The display pixel circuit is configured to control light emission of the display light-emitting element based on a data signal in accordance with video data. The reference light-emitting element is precluded from the control in accordance with video data. The display driving circuit is configured to acquire a reference signal indicating a current-voltage characteristic of the reference light-emitting element, acquire a characteristic signal indicating the current-voltage characteristic of the display light-emitting element, and generate a signal indicating a degree of deterioration of the display light-emitting element based on a difference of the characteristic signal from the reference signal.