Through-Display Shortwave Infrared Biometric Imaging
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Solution Overview
Problem
Conventional electronic devices with both display stacks and optical imaging systems require large protective covers, increasing the device's size and bezel region due to the need for separate space for the optical imaging system, which is not integrated with the display.
Innovation Solution
An electronic device design that integrates an optical imaging system, including a light emitting element and photosensitive elements, positioned below the display to emit and receive shortwave infrared light through the display, allowing for through-display biometric imaging without increasing the device's size, using a method that illuminates a contact area and assembles an image from surface reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical imaging system is positioned separately from the display stack, then the imaging function is reliable, but the protective cover size and device volume increase
Solution Approach 1:
The patent merges the optical imaging system with the display stack by positioning the imaging system between the display and the protective cover, integrating two previously separate components into a unified structure that achieves both display and imaging functions without increasing device volume
Solution Approach 2:
The patent utilizes the vertical dimension by stacking the optical imaging system within the display stack structure, transitioning from a lateral arrangement to a vertical integration that saves horizontal space while maintaining functional reliability
2Ease of operation
If the protective cover extends beyond the display periphery to accommodate the optical imaging system, then the imaging system has sufficient space, but the bezel region size increases
Solution Approach 1:
The patent combines the optical imaging system with the display stack structure, allowing the imaging system to share the same spatial envelope as the display, thereby eliminating the need for extended protective cover and reducing bezel region area
3Illumination intensity
If conventional visible light is used for imaging, then the display contrast is maintained, but subsurface reflections reduce imaging precision
Solution Approach 1:
The patent changes the wavelength parameter of the illumination light from visible light to shortwave infrared light, which penetrates the skin differently and reduces subsurface reflections, thereby improving fingerprint imaging precision while maintaining display functionality
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 biometric imaging, such as fingerprint scanning, without enlarging the device's housing, by using shortwave infrared light to minimize subsurface reflections and enhance contrast, thus reducing the apparent size of the bezel region and maintaining the device's compactness.
Implementation Method 1
a light emitting element configured to emit shortwave infrared light through the display
Implementation Method 2
a photosensitive element optically isolated from the light emitting element and configured to receive (through the display) a reflection from the interface surface
Implementation Method 3
using shortwave infrared light to minimize subsurface reflections and enhance contrast
Data Source
AI summary
Systems and methods for through-display imaging. An optical imaging sensor is positioned at least partially behind a display and is configured to emit shortwave infrared light at least partially through the display to illuminate an object, such as a fingerprint, in contact with an outer surface of the display. Surface reflections from the object are received and an image of the object can be assembled.