Display Panel Shield Electrode Parasitic Capacitance
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Solution Overview
Problem
In organic EL display devices, parasitic capacitance between the electrodes of adjacent pixels leads to luminance changes due to differences in pixel size and layout density, affecting the reference electric potential and emission luminance.
Innovation Solution
The solution involves a display panel design where the capacitor of one pixel is partially overlapped by the pixel areas of adjacent pixels, with specific electrode configurations to prevent parasitic capacitance, such as the anode electrode of one pixel being closer to the substrate than the cathode electrode, and the auxiliary capacitor's electrode being conductive with the cathode electrode of the other pixel, creating a shield effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pixels are disposed with different layout densities to optimize constituent element sizes, then manufacturing flexibility is improved, but parasitic capacitance between adjacent pixels increases causing luminance variations
Solution Approach 1:
A shield electrode is introduced as an intermediary component between adjacent pixels. This shield electrode, positioned between the auxiliary capacitor electrode of one pixel and the anode electrode of the adjacent pixel, acts as a mediator to block parasitic capacitance coupling. The shield electrode is connected to a reference potential (ground or cathode potential) to create an electrostatic shield, thereby preventing the harmful capacitive coupling while allowing the pixels to maintain different layout densities for manufacturing flexibility.
2Device complexity
If auxiliary capacitors are positioned to optimize pixel circuit layout, then device integration is improved, but parasitic capacitance with adjacent pixel electrodes increases affecting reference potential
Solution Approach 1:
The shield electrode serves as a protective intermediary positioned between the auxiliary capacitor electrode and the adjacent pixel's anode electrode. This intermediary structure blocks the parasitic capacitance pathway that would otherwise directly couple these electrodes. By introducing this shield, the auxiliary capacitor can be positioned optimally within the pixel circuit layout for high integration, while the shield prevents it from adversely affecting the reference potential of adjacent pixels through capacitive coupling.
3Adaptability or versatility
If pixel size varies to accommodate different layout densities, then manufacturing adaptability is improved, but parasitic capacitance effects on emission luminance worsen
Solution Approach 1:
The shield electrode acts as a universal intermediary protection mechanism that works regardless of pixel size variations. By positioning the shield between the auxiliary capacitor electrode and adjacent anode electrodes, it creates a consistent electrostatic barrier that prevents parasitic capacitance effects. This allows pixels to be manufactured with different sizes and layout densities to accommodate various display requirements, while the shield ensures that emission luminance consistency is maintained across all pixels by blocking the parasitic coupling that would otherwise cause luminance variations.
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 configuration effectively prevents luminance changes caused by parasitic capacitance, ensuring consistent emission luminance across pixels by isolating the influence of video signal changes in adjacent pixels.
Implementation Method 1
parasitic capacitance is generated between a source electrode of a driving transistor of the different pixel and an upper electrode of an auxiliary capacitor of the specific pixel
Implementation Method 2
a configuration in which a shield electrode, disposed between the auxiliary capacitor and the anode electrode of the other pixel, is conductive with the cathode electrode
Data Source
AI summary
A display panel including pixels disposed on a substrate, where each of the pixels includes a light emitting element, and a capacitor. The capacitor of a first one of the pixels is partially overlapped, in a vertical direction, by respective pixel areas of two of the pixels. The anode of the capacitor of the first one of the pixels may be disposed closer to the substrate than a cathode of the capacitor, thereby reducing a parasitic capacitance between the capacitor and an anode of the light emitting element of one of the two pixels overlapping the capacitor.