Under-Display Biometric Sensor With Wavelength-Selective CMOS Layer
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Solution Overview
Problem
Existing electronic devices face challenges in implementing biometric recognition technologies with thin thickness while effectively utilizing visible and infrared wavelength spectra for biometric authentication.
Innovation Solution
The electronic device integrates a CMOS sensor and a display panel that emits visible light, with a photoelectric conversion layer selectively absorbing visible wavelengths and optionally infrared wavelengths, and lacks infrared and color filters, allowing for a slim design and efficient biometric detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional biometric sensors include infrared cut-filters and color filters, then wavelength selectivity is improved, but device thickness and manufacturing complexity increase
Solution Approach 1:
The patent removes the infrared cut-filter from the biometric sensor structure. The photoelectric conversion layer is designed to inherently block infrared wavelengths through its material properties, eliminating the need for a separate infrared cut-filter while maintaining wavelength selectivity and reducing device complexity
Solution Approach 2:
The photoelectric conversion layer serves multiple functions simultaneously: it converts visible light to electrical signals for biometric detection and inherently blocks infrared wavelengths through its bandgap properties. This multi-functionality eliminates the need for separate filter components
2Reliability
If biometric sensors use separate photo-sensing devices for visible and infrared detection, then detection capability is improved, but device thickness and complexity increase
Solution Approach 1:
A single photoelectric conversion layer made of organic semiconductor material performs both visible light detection and infrared blocking functions. The material's optical properties enable it to respond to visible wavelengths for biometric authentication while naturally attenuating infrared wavelengths, eliminating the need for separate photo-sensing devices
Solution Approach 2:
The patent combines the visible light detection function and infrared blocking function into a single photoelectric conversion layer. This integration reduces the number of components and simplifies the overall sensor structure while maintaining effective biometric detection capability
3Measurement precision
If multiple filters and photo-sensing devices are used, then biometric authentication accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The infrared cut-filter is removed from the manufacturing process. The organic semiconductor photoelectric conversion layer is deposited using solution processing or vapor deposition techniques, creating a single-layer structure that inherently provides both visible detection and infrared blocking without requiring additional filter manufacturing steps
Solution Approach 2:
The patent changes the material parameter of the photoelectric conversion layer to use organic semiconductor materials with specific optical absorption characteristics. These materials have bandgap energies that correspond to visible light wavelengths, enabling them to detect visible light while blocking infrared wavelengths through their inherent electronic 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
This configuration enables effective biometric recognition with a thin form factor, enhancing performance and reducing manufacturing complexity by eliminating the need for additional filters and photo-sensing devices.
Implementation Method 1
a photoelectric conversion layer configured to selectively absorb light of a full wavelength spectrum of about 400 nm to about 700 nm
Implementation Method 2
the photoelectric conversion layer may be configured to absorb light in the at least a portion of the infrared wavelength spectrum
Data Source
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AI summary
An electronic device includes a display panel and a biometric sensor. The display panel includes a light emitter. The biometric sensor is stacked with the display panel and is configured to detect light emitted from the display panel and reflected by a recognition target that is external to the electronic device. The biometric sensor includes a silicon substrate and a photoelectric conversion element on the silicon substrate. The photoelectric conversion element includes a photoelectric conversion layer having wavelength selectivity.