Display Panel Cathode Voltage Uniformity via Third Metal Layer
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Solution Overview
Problem
Large organic light-emitting diode display panels face issues with uneven brightness due to significant cathode voltage drops at the far end, leading to non-uniform in-plane cathode voltage distribution, especially with increasing panel sizes and cathode material impedance.
Innovation Solution
A display panel design where the cathode is connected to a signal line, reducing its impedance and ensuring uniform in-plane cathode voltage distribution by incorporating a third metal layer with a signal line, a conductive layer with an anode and connection portion, and a pixel definition layer with specific opening regions for the light-emitting and cathode layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the panel size is increased, then the display area is improved, but the cathode voltage uniformity deteriorates due to significant voltage drops at the far end
Solution Approach 1:
The cathode voltage supply path is segmented into multiple sections by introducing a third metal layer with signal lines that connect to different regions of the cathode. This segmentation divides the long cathode into multiple shorter segments, each with its own voltage supply path, thereby reducing the overall voltage drop and improving voltage uniformity across the large panel.
Solution Approach 2:
The third metal layer acts as an intermediary conductive structure between the power supply and the cathode. It introduces intermediate connection points (signal lines) that mediate the voltage distribution across the cathode, reducing the direct voltage drop from the power supply to the far end of the cathode and improving voltage uniformity.
2Manufacturing precision
If the cathode material impedance is reduced, then the voltage uniformity is improved, but the device complexity increases due to additional metal layers and signal lines
Solution Approach 1:
The third metal layer is designed to serve multiple functions: it acts as a signal line for voltage distribution, provides mechanical support, and can be integrated with existing manufacturing processes. By making the third metal layer multi-functional, the patent reduces the need for additional separate structures, thereby limiting the increase in device complexity while achieving improved voltage uniformity.
3Quantity of substance
If the wiring density on the array substrate is increased, then the pixel density is improved, but the light transmittance deteriorates in bottom emission structures
Solution Approach 1:
The patent inverts the traditional bottom emission structure to a top emission structure. Instead of having the light source at the bottom and transmitting through the substrate and wiring, the light is emitted from the top through the cathode. This inversion allows for higher wiring density on the array substrate without compromising light transmittance, as the wiring no longer blocks the light path.
Data Source
AI summary
A display panel, a display module, and an electronic device are provided. The display panel includes a third metal layer including a signal line, and a conductive layer including a connection portion. The connection portion is connected to the signal line. A pixel definition layer is disposed on the conductive layer, and the pixel definition layer includes a first opening region and a second opening region. A cathode is disposed in the second opening region and disposed on the pixel definition layer. The cathode is connected to the connection portion.