Organic EL Display Pixel Circuit Sharing for High Definition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reduction of pixel size in organic EL display devices is limited by the large number of circuit elements required, particularly the drive TFT, switching TFT, and storage capacitance, which also restricts the formation of high-definition screens and increases the area occupied by current supply lines, making it difficult to achieve a miniaturized and high-definition display.
Innovation Solution
The solution involves using drive TFTs, switching TFTs, and storage capacitances in common between two adjacent pixels, reducing the area occupied by these circuit elements and sharing data and power source lines, thereby decreasing the pixel area and enabling the formation of high-definition screens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If each pixel is equipped with dedicated drive TFT, switching TFT, and storage capacitance, then the pixel circuit can accurately control the electric current in the organic EL layer, but the pixel area becomes too large to achieve high-definition screens
Solution Approach 1:
The patent merges the pixel circuits of two adjacent pixels (pixel n and pixel n+1) by sharing the drive TFT, switching TFT, and storage capacitance. The pixel circuit controller sequentially selects between the two pixels using a selection signal, allowing one set of circuit elements to control two pixels alternately, thereby reducing the area per pixel while maintaining control accuracy
Solution Approach 2:
The patent introduces dynamic time-division multiplexing control where the pixel circuit operates in different time periods to serve different pixels. The selection signal dynamically switches the connection between the shared pixel circuit and the two pixels, enabling accurate gray-scale control through temporal separation rather than spatial separation
2Reliability
If current supply lines are provided for each pixel, then each organic EL layer can receive sufficient current, but the area occupied by current supply lines increases and limits pixel miniaturization
Solution Approach 1:
The patent makes the current supply lines serve multiple functions by having them supply current to multiple pixels through the shared pixel circuit. The same current supply line structure supports both pixel n and pixel n+1, reducing the total number of current supply lines and the area they occupy while ensuring reliable current delivery to each pixel's organic EL layer
3Ease of operation
If the number of data lines and power source lines is increased to serve more pixels, then each pixel can be properly driven, but the scanning area is reduced and high-definition screens cannot be formed
Solution Approach 1:
The patent employs periodic action by sequentially driving different groups of pixels in different time periods. The pixel circuit controller alternates between pixel n and pixel n+1 using periodic selection signals, allowing a reduced number of data lines and power source lines to serve more pixels over time, thereby increasing the scanning area while maintaining proper pixel driving capability
Data Source
AI summary
The present invention allows an organic EL display device to perform display with high definition by reducing an area of each pixel forming a display region of the display device. A drive TFT for driving an organic EL element, a storage capacitance connected with a gate of the drive TFT, and a switching TFT connected to a scanning line are used in common by pixels arranged adjacent to each other in the lateral direction and hence, areas occupied by these circuit elements per one pixel can be reduced whereby the pixel can be made small. Further, a data line for supplying a video signal and a power source line for supplying an electric current to the organic EL elements can be used in common by the pixels arranged adjacent to each other and hence, the number of data lines and the number of power source lines can be halved thus reducing an area of the pixel. Due to such a constitution, the present invention acquires an organic EL display device capable of performing display with high definition.