Photo-Sensitive Element Reducing Metal Lines in LCD Aperture Ratio
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Solution Overview
Problem
Liquid crystal displays with integrated photo-sensitive elements on the TFT array substrate face reduced aperture ratio due to numerous metal lines required for driving these elements, which also complicates the assembly process and affects sensitivity to brightness variations.
Innovation Solution
A photo-sensitive element is designed with a switch thin film transistor and a photo detecting device, connected between a readout line and a switch line, eliminating the need for a bias voltage line and reducing the number of metal lines, thereby enhancing sensitivity and aperture ratio. The photo detecting device can be a photo TFT, photo diode, or light-sensitive resistor, and the switch line can provide higher voltage for increased current difference detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current type photo-sensitive element with multiple metal lines (switch line, bias line, readout line) is used, then the photo-sensitive element can be driven to measure brightness, but the aperture ratio of the liquid crystal display is reduced
Solution Approach 1:
The patent combines the bias voltage line and readout line into a single conductive line, reducing the number of metal lines from three to two. This merging of functions allows the photo-sensitive element to maintain its brightness measurement capability while reducing the area occupied by metal lines, thereby improving the aperture ratio of the liquid crystal display.
2Reliability
If a charge type photo-sensitive element with a capacitor and multiple metal lines is used, then the photo-sensitive element can store and read charge signals, but the aperture ratio is further reduced
Solution Approach 1:
The patent eliminates the need for a separate bias voltage line by integrating the bias function into the existing conductive lines. The photo-sensitive element uses the switch line and readout line for both switching and biasing functions, thereby maintaining charge storage and readout capability while reducing metal line count and improving aperture ratio.
3Adaptability or versatility
If multiple metal lines are added to the TFT array substrate for photo-sensitive elements, then the driving function is enhanced, but the manufacturing complexity and assembly process are increased
Solution Approach 1:
The patent merges the bias voltage function with the existing switch and readout lines, eliminating the need for an additional bias voltage line. This reduces the number of metal lines that need to be formed and connected on the TFT array substrate, thereby simplifying the manufacturing process and reducing assembly complexity while maintaining the photo-sensitive element's driving function.
4Measurement precision
If more metal lines are used for photo-sensitive elements, then the electrical connections are more complete, but the aperture ratio and sensitivity to brightness variations are affected
Solution Approach 1:
The patent combines the bias voltage line and readout line into a single conductive line configuration, reducing the total area occupied by metal lines. This allows a larger aperture ratio to be maintained while still providing complete electrical connections for the photo-sensitive element, thereby improving sensitivity to brightness variations.
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 allows for effective detection of light differences with reduced electrical complexity, increased aperture ratio, and improved sensitivity to brightness variations, enabling a high-sensitivity touch panel without significantly reducing the liquid crystal display's aperture ratio.
Implementation Method 1
a photo detecting device to detect a light incident thereon
Data Source
AI summary
A photo-sensitive element, a readout pixel with the photo-sensitive element, and a liquid crystal display with the readout pixels are described. The photo-sensitive element includes a switch TFT and a photo detecting device. The gate electrode of the switch TFT is electrically connected to a switch line and the source electrode of the switch TFT is electrically connected to a readout line. The photo detecting device is connected between the switch line and the drain electrode of the switch TFT for detecting the brightness of a light incident thereon. The photo detecting device is preferably a photo TFT, a photo diode, or a light sensitive resistor. The photo TFT and the switch TFT are preferably amorphous silicon transistors. The switch line is preferably a gate line disposed on the TFT array substrate of the liquid crystal display.