Pixel Electrode Segmentation for Reflective Display Luminance
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Solution Overview
Problem
In known display devices, the luminance is insufficient for reflective liquid crystal displays due to shared light-emitting regions, and the reliability of the light-emitting element is compromised by the contact hole in the insulating layer.
Innovation Solution
A display device with a first substrate featuring an upward light-emitting element and a transistor below it, a second substrate, and a liquid crystal layer in between, where the pixel electrode has a portion not overlapping the sealing film and another portion overlapping it, enhancing luminance and reliability for reflective liquid crystal displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light-emitting region is shared for both light emission display and reflective liquid crystal display, then the device structure is simplified, but the luminance is insufficient when performing reflective liquid crystal display
Solution Approach 1:
The pixel electrode is divided into two distinct portions: a first portion that does not overlap the sealing film and a second portion that overlaps the sealing film. This segmentation allows each portion to serve different functions - the first portion for reflective liquid crystal display to maximize luminance, and the second portion for light emission display, thereby resolving the contradiction between structural simplicity and luminance performance.
2Reliability
If a contact hole is formed in the insulating layer to connect pixel electrode and switching element, then electrical connection is achieved, but the reliability of the light-emitting element cannot be ensured
Solution Approach 1:
The contact hole is extracted from the sealing film structure and repositioned to connect only with the first portion of the pixel electrode that does not overlap the sealing film. This extraction eliminates the risk of moisture and oxygen penetration through the contact hole to the light-emitting element, while still achieving the necessary electrical connection between the pixel electrode and switching element.
3Illumination intensity
If the pixel electrode is fully covered by the sealing film for protection, then the light-emitting element is protected from moisture and oxygen, but the luminance for reflective liquid crystal display decreases
Solution Approach 1:
The pixel electrode is designed with different local qualities: the first portion that does not overlap the sealing film has high luminance quality for reflective liquid crystal display, while the second portion that overlaps the sealing film has high protection quality for light emission display. This local differentiation resolves the contradiction between luminance and reliability.
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
The solution increases luminance for reflective liquid crystal displays and ensures the reliability of the light-emitting element by using the non-overlapping and overlapping portions of the pixel electrode, respectively, connected through a contact hole.
Implementation Method 1
a light-emitting element that is an upward light emission type
Implementation Method 2
reflective liquid crystal display by a reflective liquid crystal element
Data Source
AI summary
A display device includes a first substrate including a light-emitting element that is an upward light emission type and a transistor in a lower layer than the light-emitting element, a second substrate facing the first substrate, and a liquid crystal layer disposed between the first substrate and the second substrate. The first substrate includes a sealing film formed in an island shape and covering the light-emitting element and a pixel electrode that is transparent. The pixel electrode includes a first portion not overlapping the sealing film and a second portion overlapping the sealing film.