OLED Pixel Circuit Reduces Temperature Luminance Sensitivity
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Solution Overview
Problem
OLED displays face challenges in designing satisfactory displays due to temperature luminance sensitivity, where variations in threshold voltage of transistors lead to inconsistent light emission, affecting image quality and requiring methods to mitigate these variations.
Innovation Solution
The implementation of a display pixel structure with extended threshold voltage sampling phase duration, separate from the data programming phase, using semiconducting oxide transistors and specific transistor configurations to reduce temperature luminance sensitivity, including anode reset and initialization transistors, and emission transistors controlled by gate driver circuitry to manage voltage and current effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the threshold voltage sampling phase duration is extended to reduce temperature luminance sensitivity, then the image quality and light emission consistency improve, but the data refresh time and overall display performance may be reduced
Solution Approach 1:
The patent segments the pixel operation into distinct phases: threshold voltage sampling phase and data programming phase. By separating these functions temporally and using different transistor configurations for each phase, the system can extend the sampling phase duration without proportionally extending the total refresh cycle, thus improving light emission consistency while maintaining acceptable refresh rates.
Solution Approach 2:
The threshold voltage sampling is performed in advance during a dedicated sampling phase before the data programming phase. This preliminary action allows the pixel to pre-compensate for threshold voltage variations, ensuring more accurate and consistent light emission during the subsequent emission phase without compromising the overall refresh timing.
2Reliability
If semiconducting oxide transistors and additional transistors (anode reset, initialization, emission) are added to manage voltage and current, then temperature luminance sensitivity is reduced, but the device complexity increases
Solution Approach 1:
The patent employs semiconducting oxide transistors that serve multiple functions: they act as drive transistors, switching transistors (data loading, gate voltage setting), and control transistors (anode reset, initialization, emission). This multi-functionality reduces the need for separate specialized components, managing device complexity while achieving reliable temperature luminance sensitivity reduction.
Solution Approach 2:
The pixel circuit is designed to self-compensate for threshold voltage variations through its own internal transistor configurations and control logic. The additional transistors enable the pixel to automatically adjust for temperature effects without requiring external intervention or complex external circuitry, thus improving reliability while keeping the overall system complexity manageable.
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 significantly reduces temperature luminance sensitivity, ensuring consistent light emission and improved image quality by extending the threshold voltage sampling phase duration and optimizing transistor configurations within the OLED display pixels.
Implementation Method 1
OLED displays have an array of display pixels based on light-emitting diodes. In this type of display, each display pixel includes a light-emitting diode and associated thin-film transistors for controlling application of data signals to the light-emitting diode to produce light.
Data Source
AI summary
A display may include an array of pixels. Each pixel in the array may include a drive transistor, emission transistors, a data loading transistor, a gate voltage setting transistor, an initialization transistor, an anode reset transistor, a storage capacitor, and an optional current boosting capacitor. A data refresh may include a initialization phase, a threshold voltage sampling phase, and a data programming phase. The threshold voltage sampling phase can be substantially longer than the data programming phase to decrease a current sampling level during the threshold voltage sampling phase, which helps reduce the display luminance sensitivity to temperature variations.