Transparent OLED Light Blocking Layers and Walls
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Solution Overview
Problem
Transparent OLED display devices face issues with external light entering from the backside, causing threshold voltage shifts in TFTs and compromising image definition due to the lack of effective light blocking mechanisms in existing opaque layers.
Innovation Solution
The implementation of a display device with a light transmitting substrate, a first light blocking layer, a thin film transistor, a first insulating layer, a second light blocking layer, and a light blocking wall to effectively block external light, preventing it from entering the light emitting region and reducing reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If opaque second insulating layer and opaque pixel defining layer are used to block external light from the front side, then image blurring caused by metal wiring reflection is suppressed, but external light from the back side cannot be blocked and causes TFT threshold voltage shift
Solution Approach 1:
The light blocking function is segmented into multiple layers: first light blocking layer for front side protection, second light blocking layer for back side protection, and light blocking wall for lateral light blocking. Each layer is positioned at different depths and orientations to comprehensively block external light from all directions, preventing both image blurring and TFT threshold voltage shift
Solution Approach 2:
The light blocking structure is extended from two-dimensional planar layers to three-dimensional configuration by adding the light blocking wall that protrudes upward from the second light blocking layer. This vertical dimension enables the structure to block light incident from various angles and directions, particularly effective against backside light entry that causes TFT threshold voltage shift
2Object-affected harmful factors
If gap between opening and TFT is widened to prevent external light from entering TFT, then light blocking is improved, but definition of the display device decreases
Solution Approach 1:
The pixel defining layer is introduced as an intermediary structure between the opening and the TFT. This layer extends over the opening and provides light blocking functionality, allowing the gap between opening and TFT to be minimized for high definition while the pixel defining layer prevents external light from reaching the TFT
Solution Approach 2:
The pixel defining layer and light blocking wall create a three-dimensional light blocking structure that extends vertically over the opening. This allows lateral light blocking without increasing the horizontal gap distance, maintaining both high definition and effective light blocking
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 enhances the display device's ability to block external light, preventing threshold voltage shifts and improving image definition by effectively blocking external light from both the front and back sides, while allowing external light to be transmitted through the light transmitting region.
Implementation Method 1
a first light blocking layer that is disposed in the light emitting region and blocks the external light
Implementation Method 2
a second light blocking layer that is disposed on the first insulating layer so as to cover the thin film transistor and blocks the external light
Implementation Method 3
a first light blocking wall that is connected to the first light blocking layer and the second light blocking layer and blocks the external light
Implementation Method 4
pixels having a light transmitting region that transmits external light
Data Source
AI summary
A display device includes a light transmitting substrate in which pixels are arranged, the pixels having a light transmitting region that transmits external light and a light emitting region in which a light emitting element is disposed; a first light blocking layer that is disposed in the light emitting region and blocks the external light; a thin film transistor that is disposed on the first light blocking layer and controls a light emission of the light emitting element; a first insulating layer that covers an active layer of the thin film transistor; a second light blocking layer that is disposed on the first insulating layer so as to cover the thin film transistor and blocks the external light; and a first light blocking wall that is connected to the first light blocking layer and the second light blocking layer and blocks the external light.