Infrared Backlight Multi-Touch Display with Reflected Light Sensing
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Solution Overview
Problem
Existing multi-touch display technologies face inaccuracies in touch location recognition due to direct infrared light illumination, reduced effective display surface area, and complex systems with long signal paths, which limit their multi-touch recognition capability and design flexibility.
Innovation Solution
A touch-sensing display screen with an upper and lower transparent substrate, a backlight unit featuring an infrared light source, and an infrared light-sensing thin-film transistor (IR TFT) that activates pixel electrodes and senses infrared light reflected from touch points, allowing for accurate multi-touch recognition without the need for extensive IR arrays or complex camera-projector systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If IR arrays are arranged at the side surface of the transparent acrylic plate, then the device becomes thin, but the multi-touch recognition accuracy deteriorates due to direct illumination by infrared light
Solution Approach 1:
Instead of placing IR arrays at the side surface (conventional approach), the patent inverts the arrangement by positioning the infrared light source at the backlight unit behind the display and placing IR sensors at specific locations on the front surface, using reflected infrared light from touch points rather than direct illumination
2Device complexity
If IR arrays are arranged at the side surface of the transparent acrylic plate, then the device structure is simplified, but the effective display surface area is reduced due to area occupied by the IR arrays
Solution Approach 1:
The patent moves the infrared sensing function from the lateral dimension (side surface arrays) to the vertical dimension (backlight unit integration), allowing IR sensors to be positioned at specific locations rather than spanning the entire side surface, thereby preserving effective display area
3Ease of operation
If a camera and projector module are used for multi-touch sensing, then touch detection is achieved, but the system complexity increases and space occupation increases
Solution Approach 1:
The patent extracts only the essential infrared sensing function from the complex camera-projector system, using dedicated IR sensors that detect reflected infrared light from touch points, eliminating the need for complex image processing and cable connections to external computers
4Ease of operation
If a camera and projector module are used with long distance from the transparent acrylic plate, then touch detection is achieved, but the space occupied by the device increases
Solution Approach 1:
The patent merges the infrared sensing function with the display panel structure itself by integrating IR sensors into the display module, eliminating the need for separate camera-projector modules positioned at a distance, thereby reducing overall device volume
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
The solution provides accurate multi-touch recognition with a thin, compact design that enhances the effective display surface area and simplifies the system, enabling precise coordinate calculation and display of touch points while reducing component complexity and space occupation.
Implementation Method 1
a backlight unit having an infrared light source configured to radiate infrared light through the upper substrate in a first direction
Implementation Method 2
A portion of the infrared light radiated in the first direction is reflected back through the upper substrate and through the transparent window in a second direction by an object touching a surface of the upper transparent substrate
Implementation Method 3
an infrared light-sensing thin-film transistor is configured to sense the infrared light received through the upper substrate in the second direction, and output an infrared light-sense signal in response thereto
Data Source
AI summary
A touch-sensing display screen includes an upper transparent substrate, a lower substrate opposite the upper substrate, and a backlight unit having an infrared light source configured to radiate infrared light through the upper substrate in a first direction. A transparent window is disposed in alignment with the infrared light source and between the upper and lower transparent substrates. A portion of the infrared light radiated in the first direction is reflected back through the upper substrate and through the transparent window in a second direction by an object touching a surface of the upper transparent substrate. A pixel thin-film transistor on the lower substrate is configured to activate a pixel electrode, and an infrared light-sensing thin-film transistor is configured to sense the infrared light received through the upper substrate in the second direction, and output an infrared light-sense signal in response thereto.