Display Apparatus Light Emitting Region Expansion via Segmented Electrodes
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Solution Overview
Problem
Emissive display apparatuses face limitations in increasing the size of light emitting regions due to the presence of contact portions between lower electrodes and wiring patterns, which restricts light emission efficiency.
Innovation Solution
Incorporating the contact portion of the lower electrode into the light emitting region and using a pixel driving circuit to function the light emitting element as a capacitive element in reverse bias, while employing a color filter to mitigate color shifts caused by thickness variations in the light emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the contact portion of the lower electrode is excluded from the light emitting region, then the electrical connection is ensured, but the light emitting area is reduced
Solution Approach 1:
The lower electrode is divided into two distinct portions: a contact portion that ensures electrical connection and a light emitting region portion that maximizes light emission area. This segmentation allows each portion to fulfill its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the lower electrode are assigned different functional qualities: the contact portion is optimized for electrical connection with the wiring pattern, while the light emitting region portion is optimized for light emission. This local differentiation resolves the contradiction by allowing each area to serve its primary purpose.
2Reliability
If the light emitting layer thickness is increased at the contact portion, then the electrical connection is improved, but color shifts occur due to thickness variations
Solution Approach 1:
An insulating film is deposited in advance over the entire lower electrode surface, including the contact portion, before forming the light emitting layer. This preliminary insulating layer prevents direct contact between the light emitting layer and the lower electrode at the contact portion, thereby preventing color shifts while still allowing electrical connection through the insulating film.
3Productivity
If the light emitting region is expanded to include the contact portion, then the light emission efficiency is improved, but the manufacturing precision is compromised
Solution Approach 1:
An insulating film serves as an intermediary layer between the lower electrode and the light emitting layer at the contact portion. This intermediary allows the light emitting region to be expanded to include the contact portion area while maintaining clear manufacturing boundaries through the insulating film's defined edges, thus preserving manufacturing precision.
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 approach allows for a larger light emitting region, enhancing light emission efficiency by including the contact portion and optimizing the light emitting area, thereby improving the display's overall performance.
Implementation Method 1
a light emitting element is disposed between an anode and a cathode and light is emitted by applying a voltage to the element
Implementation Method 2
a pixel driving circuit of a display apparatus causes a light emitting element to function in a reverse bias as a capacitive element
Data Source
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AI summary
There is provided a display apparatus including a wiring pattern (125) formed over a substrate (111), a first insulating film (130) which is laminated over the wiring pattern and in which a contact hole (130c) is formed in an up-down direction at a specified position, lower electrodes (140) each formed over the first insulating film and including a contact portion (140c) that is inserted through the contact hole and electrically connected to the wiring pattern, a light emitting layer (150) formed over the lower electrodes, an upper electrode (160) formed over the light emitting layer, a light emitting region regulating member (170) regulating a light emitting region (El) where the light emitting layer is interposed between the lower electrodes and the upper electrode as a region including the contact portion, and a color filter disposed over the substrate in a region corresponding to at least the contact portion.