Image Display Apparatus Photo Sensor Integration for High-Accuracy Touch
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Solution Overview
Problem
Existing image display apparatus with integrated photo sensors for touch input suffer from low accuracy and high-speed limitations due to variations in sensor characteristics, increased peripheral circuitry, and a decrease in pixel aperture ratio, leading to reduced screen brightness and shorter operating times in portable devices.
Innovation Solution
The solution involves forming photo sensors and detection signal lines on a glass substrate using thin film transistors, where detection and reference signal lines are adjacent to each other, eliminating signal current components and temperature effects, and utilizing a differential amplifier to process signals, thereby reducing the need for additional circuitry and maintaining high pixel aperture ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photo sensors are installed on the edge of the display region or outside the display region, then the touch detection function is achieved, but the accuracy is low due to variations in element characteristics and temperature characteristics
Solution Approach 1:
The patent applies local quality by creating different photo sensor configurations in different regions of the display panel. Reference photo sensors are positioned in specific locations (edge or outside display region) while signal photo sensors are distributed across the display region. This spatial differentiation allows the system to compensate for variations in element and temperature characteristics by using the reference sensors to calibrate the signal sensors locally, thereby improving touch detection accuracy without compromising reliability.
2Measurement precision
If multiple photo sensors and processing circuits are added to the display panel, then touch detection capability is improved, but the pixel aperture ratio decreases and screen brightness is reduced
Solution Approach 1:
The patent merges the photo sensor function with the existing pixel structure by integrating photo sensors into the display panel's pixel regions. The reference photo sensors are positioned in the same physical plane as the display pixels, allowing them to share the same light path and structural space. This merging approach enables touch detection functionality to be added without requiring separate, additional components that would block light and reduce screen brightness.
3Area of stationary object
If photo sensors are positioned away from each other, then the detection coverage is expanded, but the transmission accuracy of detection signals is reduced due to resistance differences among signal lines
Solution Approach 1:
The patent applies equipotentiality by positioning reference photo sensors and signal photo sensors at comparable distances from the center of the display region. The reference photo sensors are strategically placed (either on the edge or outside the display region) to maintain similar light path lengths and signal transmission distances as the signal photo sensors. This spatial arrangement ensures that both types of sensors experience comparable electrical conditions, minimizing resistance differences in the signal lines and improving overall detection signal accuracy.
4Adaptability or versatility
If additional processing circuits are added to the display panel, then the image entry function is enhanced, but the device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the photo sensor system to serve both as a display component and a touch detection component. The same pixel structure that displays images also contains photo sensors for touch detection, allowing the display panel to perform multiple functions (visual display and input detection) simultaneously. This approach enhances the image entry function without requiring separate dedicated touch sensing layers or additional peripheral circuits, thereby reducing overall device complexity.
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 enables high-speed, high-accuracy touch detection without increasing peripheral components, reduces power consumption, and maintains screen brightness by internalizing photo sensors within the display apparatus, enhancing the operational efficiency of portable terminals.
Implementation Method 1
a first photo sensor PIXS for receiving external light LREF irradiated from the liquid crystal display panel surface
Implementation Method 2
a differential amplifier for processing the detection signal in the sensor signal processing circuit
Data Source
AI summary
An image display apparatus with image entry function capable of high-speed and high-accuracy direct screen entry without increasing the peripheral circuit scale or the number of circuit elements for each pixel that lower the pixel aperture ratio. A first pixel circuit and a second pixel circuit are alternately arrayed horizontally. First and second data lines are connected to a data driver and a sensor signal processor circuit. Selector switches are connected to the input terminal of the data driver. Gray scale voltages are sent from the data driver to the first and second data lines, and first and second photo sensor signals are sent to the sensor signal processor circuit.