TFT Photodetector Touch Panel Using Display Light for Fast Sensing
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Solution Overview
Problem
Current display systems lack the ability to efficiently acquire input signals directly, with touch screens only providing a one-way output function and requiring separate light emitters for touch sensing.
Innovation Solution
Implementing a high-sensitivity touch panel using thin film transistor (TFT) photodetectors on a glass or flexible substrate, which utilize the display's light source for touch sensing, integrating display and touch panels on the same panel, and fabricating switching TFTs and driving TFTs in a single process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate light emitter is provided for touch sensing, then touch sensing capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The display panel's light emitting components serve dual purposes: displaying visual information and providing illumination for touch sensing. This multi-functional approach eliminates the need for separate touch panel light emitters, reducing device complexity while maintaining reliable touch sensing capability.
Solution Approach 2:
The patent combines the display function and touch sensing function into a single integrated panel structure. The display pixels and touch sensing photodetectors are fabricated together on the same substrate, merging two previously separate systems into one unified device.
2Ease of manufacture
If display and touch panels are integrated on the same panel, then manufacturing process is simplified, but manufacturing precision requirements increase
Solution Approach 1:
The integrated panel is divided into distinct functional regions: display pixel areas and touch sensing photodetector areas. This segmentation allows each region to be optimized and fabricated using appropriate processes while maintaining overall integration, balancing ease of manufacture with manufacturing precision requirements.
Solution Approach 2:
The patent employs different material parameters and fabrication conditions for different regions of the integrated panel. By adjusting deposition parameters, annealing temperatures, and layer thicknesses locally, the manufacturing process accommodates both display and touch sensing requirements without compromising precision.
3Speed
If TFT photodetectors are used for touch sensing, then touch recognition speed is improved, but sensitivity may be compromised
Solution Approach 1:
The patent uses composite material structures for the photodetectors, combining multiple layers with complementary properties. This includes optimized semiconductor layers, charge transport layers, and electrode materials that work together to achieve both fast response speed and high sensitivity for accurate touch recognition.
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
Enables accurate and fast touch recognition without additional light emitters, simplifying device fabrication and reducing costs by using the display's light source for both display and touch sensing, and extending the wavelength range for light detection.
Implementation Method 1
a touch panel including at least one unit pattern for sensing light reflected by a touch by using a TFT photodetector
Data Source
AI summary
A touch screen panel using a thin film transistor (TFT) photodetector includes a touch panel including a plurality of unit patterns for sensing light reflected by a touch by using a TFT photodetector including an active layer formed of amorphous silicon or polycrystalline silicon on an amorphous transparent material, and a controller configured to scan the plurality of unit patterns and read touch coordinates as a result of the scanning.