Light Emitting Display Panel Cathode Voltage Distribution
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Solution Overview
Problem
As light emitting display panels increase in size, the cathode voltage becomes unevenly distributed, leading to a degradation in display quality due to voltage shifts at different positions, affecting the overall performance and brightness consistency.
Innovation Solution
A light emitting display panel design where the cathode is connected to an auxiliary cathode electrode through an undercut region beneath a planarization layer, ensuring uniform cathode voltage distribution across the panel by exposing the connection electrode at specific regions, such as the bank and passivation layer, to maintain consistent brightness and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the light emitting display panel is enlarged in size, then the display area is increased, but the cathode voltage becomes unevenly distributed causing quality degradation
Solution Approach 1:
The cathode voltage supply system is segmented into multiple independent paths by introducing auxiliary cathode electrodes at different positions (first auxiliary cathode electrode at one end, second auxiliary cathode electrode at the other end) in addition to the main cathode electrode. This segmentation allows voltage to be distributed through multiple routes, preventing uneven voltage distribution in large-sized panels and resolving the contradiction between increased display area and maintained voltage uniformity.
2Reliability
If the cathode is connected through multiple layers including planarization layer, then voltage distribution is improved, but the device structure becomes more complex
Solution Approach 1:
The connection structure extends into the vertical dimension by passing through multiple stacked layers (planarization layer, bank layer, encapsulation layer) to reach the auxiliary cathode electrodes. This multi-dimensional routing allows the connection to bypass horizontal space constraints and achieve voltage distribution across large areas without significantly increasing lateral structural complexity.
Solution Approach 2:
The connection electrode serves as an intermediary element that bridges the cathode and auxiliary cathode electrodes through multiple insulating and structural layers. This intermediary component enables electrical connection while navigating through the complex multi-layer structure, maintaining voltage uniformity without requiring direct exposure or simplified layering.
3Reliability
If the connection electrode is exposed at the undercut region, then cathode voltage supply is improved, but the manufacturing process becomes more difficult
Solution Approach 1:
The undercut region is formed in advance during the manufacturing process, before final assembly and testing. This preliminary formation of the undercut region allows subsequent connection electrodes to be easily positioned and connected to auxiliary cathode electrodes, ensuring proper cathode voltage supply while managing manufacturing complexity through staged process planning.
Data Source
AI summary
A light emitting display panel and a light emitting display apparatus including the same, in which a cathode is connected to an auxiliary cathode electrode through an undercut region provided under a planarization layer, are provided. The light emitting display panel includes a substrate, an auxiliary cathode electrode provided in the substrate, a passivation layer covering the auxiliary cathode electrode, an anode provided on the passivation layer, a bank surrounding an outer portion of the anode, a light emitting layer provided on the anode, and a cathode provided on the light emitting layer, the cathode is connected to the auxiliary cathode electrode through a connection electrode exposed at an undercut region passing through the bank and the passivation layer.