Display Pixel Vertical Stacking for Biometric Sensing
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Solution Overview
Problem
Current display technologies lack an efficient method to simultaneously display images and sense biometric information, particularly in a thin and flexible form factor, while minimizing signal and color interference between light-emitting devices emitting different wavelength bands.
Innovation Solution
A display apparatus with a substrate featuring first and second pixels emitting light in different wavelength bands, a light sensor for sensing reflected light, and a light shield to prevent interference, where the second light-emitting device is arranged below the first and separated to reduce overlap, and the light sensor includes a thin film transistor with an amorphous silicon germanium semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light-emitting devices emitting different wavelength bands are arranged in the same pixel region, then the device can simultaneously display images and sense biometric information, but signal interference and color crosstalk occur between the different wavelength bands
Solution Approach 1:
The pixel is divided into distinct first pixel regions and second pixel regions, with each region dedicated to a specific wavelength band (visible light for display, infrared for sensing). This spatial segmentation eliminates signal interference between different wavelength bands while enabling simultaneous operation of both display and biometric sensing functions.
Solution Approach 2:
The patent utilizes the vertical dimension by arranging the first light-emitting device and second light-emitting device at different depths within the pixel structure. The second light-emitting device (infrared) is positioned below the first light-emitting device (visible), allowing both to coexist in the same pixel region without lateral interference, thus enabling simultaneous image display and biometric sensing.
2Length of stationary object
If multiple light-emitting devices are stacked in the same pixel region, then the device thickness can be reduced, but color interference and signal overlap increase
Solution Approach 1:
The patent employs vertical stacking of light-emitting devices at different depth levels within the pixel. The first light-emitting device (visible wavelength) is positioned above the second light-emitting device (infrared wavelength), utilizing the vertical dimension to reduce device thickness while maintaining spectral separation through the light shield and spatial arrangement.
Solution Approach 2:
A light shield is introduced as an intermediary element between the first light-emitting device and the second light-emitting device. This light shield selectively blocks visible light from reaching the infrared sensor while allowing infrared light to pass through, thereby preventing color interference and signal overlap between the different wavelength bands.
3Adaptability or versatility
If a light sensor is added to sense reflected light for biometric information, then biometric sensing capability is enabled, but the device structure becomes more complex
Solution Approach 1:
The pixel structure is designed to serve multiple functions: the first light-emitting device and first pixel region handle visible light display, while the second light-emitting device and light sensor handle infrared light emission and detection for biometric sensing. This multi-functional integration enables both display and biometric sensing within a unified pixel structure, reducing overall system complexity.
Solution Approach 2:
The patent merges the display function and biometric sensing function into a single integrated pixel structure. The light sensor is combined with the light-emitting devices in the same pixel region, and the light shield serves dual purposes by both protecting the sensor and enabling spectral separation. This merging reduces the need for separate display and sensing modules, simplifying the overall device structure.
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 simultaneous image display and biometric information sensing with reduced signal and color interference, allowing for a thin and flexible form factor suitable for applications like vein pattern extraction.
Implementation Method 1
a light sensor on the substrate to sense light in the second wavelength band emitted from the second pixel and reflected by an object
Implementation Method 2
a light shield adjacent to the light sensor on the substrate
Implementation Method 3
a first pixel on the substrate, the first pixel including a first light-emitting device to emit light in a first wavelength band in a first direction
Implementation Method 4
a second pixel on the substrate, the second pixel including a second light-emitting device to emit light in a second wavelength band in a second direction different from the first direction
Data Source
AI summary
A display apparatus includes a first pixel, a second pixel, a light sensor, and a light shield. The first pixel has a first light-emitting device which includes a first emission layer that emits light in a first wavelength band in a first direction. The second pixel has a second light-emitting device which includes a second emission layer to emit light in a second wavelength band in a second direction different from the first direction. The second emission layer is below the first emission layer of the first light-emitting device. The light sensor senses light in the second wavelength band emitted from the second pixel and reflected by an object. The light shield is arranged along a light path incident to the light sensor.