OLED Light Emission Control for Gray Spot Compensation
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Solution Overview
Problem
Active matrix OLED displays face challenges in achieving accurate gray expression and clear image quality due to threshold voltage distribution variations among driving transistors, which lead to gray spots and reduced display quality, especially when scaling up to larger panels and high-speed frame rates.
Innovation Solution
A display device and driving method that compensate for threshold voltage distribution by controlling light emission periods for each pixel using a light emission controller, which generates specific switching control signals to adjust the operation of light emission transistors, allowing for varying light emission times across frames to maintain consistent luminance and prevent gray spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed frame rates are used to maintain display performance, then productivity is improved, but gray spot compensation accuracy deteriorates due to insufficient compensation time
Solution Approach 1:
The patent segments the light emission period into multiple sub-periods within a frame, allowing different pixels to be driven in different time slots. This segmentation enables thorough gray spot compensation for each pixel without requiring high frame rates, as the compensation can be performed sequentially during the light emission phase.
Solution Approach 2:
The patent performs gray spot compensation in advance during the light emission control phase by pre-calculating and applying compensation values to the driving transistors before the actual light emission occurs. This preliminary compensation action ensures accurate gray expression without needing high frame rates during the display refresh.
2Manufacturing precision
If light emission control is applied to compensate threshold voltage variations, then gray spot compensation accuracy is improved, but device complexity increases due to additional control circuits
Solution Approach 1:
The patent makes the light emission control transistor serve multiple functions: it acts as both a switching element for the driving transistor and a control element for gray spot compensation. By integrating the compensation function into the existing light emission control structure, the patent avoids adding separate dedicated compensation circuits, thus limiting the increase in device complexity.
Solution Approach 2:
The system performs self-compensation by using the light emission control transistor to automatically adjust the driving transistor's operation based on measured threshold voltage variations. The compensation is self-regulating through feedback from the light emission characteristics, eliminating the need for external complex compensation circuits.
3Measurement precision
If multiple light emission control transistors are used for precise control, then gray expression accuracy is improved, but ease of operation deteriorates due to complex control signals
Solution Approach 1:
The patent dynamically adjusts the light emission control transistor's operation based on the specific gray level being displayed and the measured threshold voltage variations. By making the control adaptive and dynamic rather than static, the system achieves precise gray expression while the control signals remain manageable through algorithmic optimization rather than increased hardware 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 effectively prevents gray spots and ensures clear image quality by compensating for threshold voltage variations, allowing for stable and accurate gray scale reproduction without the need for high-speed frame rates, thus improving the overall image quality and reducing the occurrence of gray spots.
Implementation Method 1
An organic light emitting diode (OLED) display displays an image by using an OLED which generates light by recoupling an electron and a hole
Data Source
AI summary
A display device is disclosed. In one aspect, the device includes a display panel that includes i) a plurality of pixels including first and second light emission control transistors, ii) a first light emission driver configured to generate a first switching control signal, iii) a second light emission driver configured to generate a second switching control signal, iv) a signal controller configured to generate and transfer a first light emission control signal and v) a light emission controller configured to generate and transfer a second light emission control signal. The light emission controller acquires information of a gray depth from a result value obtained by summing gray data, determines a light emission control algorithm according to the gray depth, and generates the second light emission control signal so that the pixels emit light during different light emission periods for a plurality of frames.