A degradation model for blue fluorescent OLEDs for compensation of decreased pixel luminance and lifetime enhancement of OLED displays

有机发光二极管退化模型的目的是确定有机发光二极管显示寿命期间的效率。这可以补偿像素的差异老化，并抑制OLED显示器最大的问题——图像粘滞。在之前的项目中，开发了OLED退化的相关模型和数据计数模型。相关模型将可测量电流的漂移与效率的漂移相关联，而数据计数模型则根据OLED像素的累积应力计算效率的下降。从关联模型和/或数据计数模型中获得的效率被存储为老化状态，并用于下一级退化模型，即光电模型。通过这种方法，可以模拟对老化状态和工作点的依赖效率。这个新的项目应用的目标是利用基于这种新的电光模型的实时补偿算法来抑制图像粘滞伪影。这应该使模型适用。在新项目的第一阶段，将结合相关模型和数据计数模型的优势。在光电模型的基础上，推导出一种确定效率与老化状态和工作点的函数关系的具体算法。这一事实可能有利于将老化状态视为实时运行的常数。数字化驱动在老化补偿方面具有一定的优势。工作点位于一个相对狭窄的范围内，色移很小。基于时间的数字驱动可以方便、准确地实现补偿所需的更高灰度分辨率。然而，数字amoled的图像分解需要一定的复杂性。图像分解和老化补偿是一个相互依赖的系统，因此必须特别注意算法的效率。在逻辑复杂度适度增加的情况下，设计和开发一种图像分解和老化补偿的集成方法。退化模型的价值主要在于抑制图像粘滞伪影，这只能通过HW验证来确认和评价。该算法在FPGA中实现，旨在驱动我们专门为此目的设计的中等尺寸和高分辨率的数字AMOLED原型。通过用户测试，可以评估老化补偿的有效性，并可以量化OLED显示器的寿命增强。最后，指出了模拟驾驶老化补偿的潜在挑战。

The aim of an OLED degradation model is to determine the efficiency of an OLED during the lifetime of an OLED display. This enables the compensation of the differential aging of the pixels and the suppression of the biggest problem of an OLED display, image sticking.In the previous project, a correlation model and a data counting model for the OLED degradation were developed. The correlation model correlates the measurable current drift with the drift of the efficiency, while the data counting model calculates the decreased efficiency from the accumulated stresses of the OLED pixel. The efficiency obtained from the correlation model and/or the data counting model is stored as the aging state and used for the next level of the degradation model, the electro-optical model. In this way, the efficiency in dependence on the aging state and the operating point can be simulated.The goal of this new project application is to suppress the image sticking artifact with a real-time compensation algorithm based on this novel electro-optic model. This should make the model applicable.In the first phase of the new project, the strengths of the correlation model and the data counting model will be combined. A specific algorithm is to be derived which, based on the electro-optical model, determines the efficiency as a function of the aging state and the operating point. The fact may be beneficial that the aging state for the real time operation can be considered as constant.Digital driving of AMOLEDs has some advantages particularly for the aging compensation. The operating point lies in a relatively narrow range with little color shift. The higher gray scale resolution necessary for the compensation can be easily and accurately realized with time-based digital driving. The image decomposition for digital AMOLEDs, however, requires some complexity. The image decomposition and the aging compensation form an interdependent system, so that special attention must be paid to the efficiency of the algorithm. An integrated method for image decomposition and aging compensation will be designed and developed in such a way that the logic complexity will increase just moderately.The value of the degradation model lies mainly in the suppression of the image sticking artifact, which can only be confirmed and evaluated by HW validation. The algorithm is implemented in an FPGA and is intended to drive a digital AMOLED prototype of medium size and high resolution specifically designed by us for that purpose. By performing a user test, the effectiveness of the aging compensation can be evaluated and the lifetime enhancement of OLED displays can be quantified. Finally, the potential challenges of aging compensation for analog driving are to be identified.