OLED Display Touch Electrode Routing for Sensor Light Transmission
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Solution Overview
Problem
Display devices with organic light emitting diodes (OLEDs) face challenges in maintaining display quality and ensuring sufficient light transmission for illumination sensors due to the presence of electrodes and metal lines, which can obstruct light paths and lead to misalignment issues.
Innovation Solution
The display device incorporates a crank-like shape for the metal lines of the touch panel electrodes, ensuring they do not overlap the light-emitting areas, and includes transmissive regions to allow sufficient light entry for illumination sensors, even with potential misalignments during manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If touch panel electrodes and metal lines are provided in the display area, then touch panel function is achieved, but display quality is reduced due to obstruction of light paths
Solution Approach 1:
The metal lines are designed to extend in the third dimension (depth direction) rather than only in the planar display area. By positioning metal lines at different heights and using the depth dimension, the design allows light to pass through the display area without being blocked, while still providing the necessary electrical connection for touch panel function.
Solution Approach 2:
The display area is divided into light-emitting regions and transmissive regions. The metal lines are positioned specifically in transmissive regions where they do not interfere with light emission, allowing the touch panel function to coexist with display quality by spatially segmenting the functions.
2Illumination intensity
If transmissive region is provided for illumination sensor, then light transmission is improved, but display area is reduced
Solution Approach 1:
Different regions of the display device are assigned different functions: some regions are optimized for light emission while others are designated as transmissive regions for the illumination sensor. This local differentiation allows both display quality and illumination sensor functionality to coexist without compromising either.
Solution Approach 2:
The illumination sensor is positioned on the back side of the substrate, utilizing the depth dimension to separate the light transmission path from the display area. This allows the transmissive region to be located in the display area while the sensor itself is positioned in the third dimension, minimizing the impact on display area.
3Illumination intensity
If metal lines are positioned to avoid light-emitting areas, then display quality is maintained, but manufacturing precision requirements increase
Solution Approach 1:
The design preemptively positions metal lines in transmissive regions that are predetermined to be free from light-emitting areas. By planning the metal line placement in advance within safe zones, the design reduces the impact of potential manufacturing variations and maintains display quality without requiring extremely tight manufacturing tolerances.
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 design maintains display quality by preventing reductions in the light-emitting area while enabling accurate illuminance measurement by the illumination sensor, ensuring reliable operation despite manufacturing inaccuracies.
Implementation Method 1
a display element consisting of a lower electrode, an upper electrode which faces the lower electrode, and an organic layer which is provided between the lower electrode and the upper electrode and emits light based on a potential difference between the lower electrode and the upper electrode
Data Source
AI summary
According to one embodiment, a display device includes a substrate, a plurality of pixels each of which includes a display element consisting of a lower electrode, an upper electrode and an organic layer, a partition, a touch panel electrode which detects an object which contacts or approaches a display area, and an illumination sensor which is provided on a back side of the substrate and measures an illuminance of light which enters the display device through a front side of the substrate. Each of the pixels includes a transmissive region in which the display element is not provided. The touch panel electrode includes a metal line located above the partition, extending along the partition and having a crank-like shape near a transmissive region included in each of the pixels.