OLED Precharge Voltage Control for Charging Uniformity
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Solution Overview
Problem
Organic light-emitting display devices face challenges in providing effective precharge voltages to pixels, leading to varying charging characteristics and increased power consumption, especially as the size and resolution of these devices increase, resulting in deteriorated display quality.
Innovation Solution
The implementation of a precharge voltage unit that selectively provides precharge voltages to specific pixel column blocks, with varying voltage levels and durations, to optimize charging characteristics and reduce power consumption, by dividing each frame into sub-frames and alternating the activation of scan drivers to apply scan signals in opposite directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precharge voltage is supplied to all pixels, then charging characteristics of pixels are improved, but power consumption increases considerably
Solution Approach 1:
The patent applies precharge voltage selectively to specific pixel column blocks (first pixel column block) rather than all pixels. The scan driver is configured to provide precharge voltage only to pixels that receive scan signals before other pixels, based on their position and scanning order. This localized approach improves charging characteristics where needed while avoiding unnecessary power consumption in other regions.
2Reliability
If number of sub-frames increases, then display quality improves, but charging time per pixel decreases
Solution Approach 1:
The patent applies precharge voltage to pixels in advance before the actual data voltage is supplied. By precharging the pixels in the first pixel column block before scanning, the system ensures that pixels are ready to receive data voltage quickly, compensating for the reduced charging time caused by increased number of sub-frames required for high display quality.
3Speed
If scan signal is applied to all pixels simultaneously, then scanning speed is maintained, but charging uniformity deteriorates
Solution Approach 1:
The patent recognizes that pixels at different positions have different charging characteristics due to their distance from the scan driver. It applies precharge voltage specifically to pixels in the first pixel column block that experience greater voltage drops, while pixels in the second pixel column block receive normal scanning without precharge. This differentiated approach maintains scanning speed while improving charging uniformity across the display.
Data Source
AI summary
An organic light-emitting display device which divides each frame into a plurality of sub-frames and represents gray levels based on the sum of the lengths of one or more sub-frames during which light is emitted, the organic light-emitting display device comprising a display unit including a plurality of pixels arranged in a matrix, a scan driver configured to provide a scan signal to the display unit during each sub-frame period and a precharge voltage unit configured to provide a precharge voltage to the pixels, wherein the pixels are divided into a first pixel column block including a pixel receiving the scan signal before the other pixels and a second pixel column block next to the first pixel column block in a direction of the application of the scan signal and the precharge voltage is selectively provided to pixels included in the first pixel column block.