Integrated Touch Sensing in LCD Pixel Arrays
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Solution Overview
Problem
Conventional liquid crystal display (LCD) touch screen panels are expensive to manufacture, have low yield rates, and result in reduced luminance and increased thickness due to the integration of touch screen mechanisms, which also occupy significant space and interfere with pixel signal lines.
Innovation Solution
A display device design that incorporates photo and pressure sensing units between pixels, using amorphous silicon or polysilicon thin film transistors, with sensor data lines and scanning lines to detect touch inputs without the need for a separate touch screen panel, allowing for integrated touch functionality without compromising display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate touch screen panel is integrated with LCD, then touch functionality is achieved, but manufacturing cost increases and yield rate decreases
Solution Approach 1:
The patent merges the touch sensing function with the LCD pixel structure by integrating sensing units directly into the pixel array. The sensing units share the same substrate, thin-film transistor fabrication process, and electrode structure with the display pixels, eliminating the need for a separate touch screen panel assembly and reducing manufacturing complexity
Solution Approach 2:
The thin-film transistor and electrode structures serve dual purposes: driving display pixels and operating sensing units. The same ITO electrodes and TFT circuits are used for both liquid crystal control and touch signal detection, allowing one structure to perform multiple functions without requiring additional dedicated components
2Adaptability or versatility
If a separate touch screen panel is integrated with LCD, then touch functionality is achieved, but luminance decreases and thickness increases
Solution Approach 1:
The sensing units are merged with the pixel structure at the same substrate level, eliminating the need for additional overlay layers that would block light. The sensing electrodes are positioned within the same plane as the display electrodes, ensuring no reduction in light transmission and maintaining original luminance characteristics
3Adaptability or versatility
If sensors are incorporated into pixels, then touch detection is enabled, but aperture ratio decreases due to sensor and signal line area
Solution Approach 1:
The same electrode areas serve dual purposes as both display pixels and sensing units. The ITO electrodes and TFT structures are not additional elements but rather multi-functional components that simultaneously drive display and detect touch, eliminating the need for separate sensor areas and preserving aperture ratio
Solution Approach 2:
The sensing units utilize portions of the existing pixel structure that would otherwise be non-display areas. By positioning sensing units in regions between or adjacent to active pixels while sharing infrastructure, the design achieves touch detection without significantly encroaching on the light-emitting aperture area
4Adaptability or versatility
If sensors are incorporated into pixels, then touch detection is enabled, but signal lines are disturbed by pixel signal lines
Solution Approach 1:
The same signal lines carry both display control signals and touch sensing signals at different times. The TFT switching circuits selectively route signals to either pixel electrodes or sensing unit electrodes based on operational mode, allowing shared infrastructure without permanent interference
Solution Approach 2:
The display and sensing operations are performed in alternating time periods. During display refresh cycles, pixel signal lines are active; during touch detection cycles, sensing signal lines are active. This temporal separation prevents simultaneous interference and allows both functions to share the same physical infrastructure
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 enhances the aperture ratio of the LCD, reduces manufacturing costs, and maintains luminance while providing effective touch detection, enabling precise touch recognition without the thickness and cost issues of traditional touch screen panel integration.
Implementation Method 1
a photo sensing unit receiving light, generating an output signal based on the received light
Implementation Method 2
pressure sensing units generating an output signal based on a pressure exerted on the display panel
Data Source
AI summary
A display device according to an embodiment of the present invention includes: a display panel; a plurality of pixels disposed on the display panel; a plurality of sensor data lines disposed on the display panel and disposed between two adjacent pixels; and a plurality of sensing units disposed on the display panel and disposed between two adjacent pixels.