Under-screen optical sensor module with pinhole lens for fingerprint sensing
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Solution Overview
Problem
Conventional fingerprint sensors in electronic devices often require a separate footprint, conflicting with the need for a compact design and high spatial image resolution, and are prone to security issues due to password vulnerabilities.
Innovation Solution
An optical sensor module integrated under the display panel captures fingerprint patterns using returned light from the display screen, employing a pinhole layer, optical layers, and a lens unit for enhanced imaging resolution, while minimizing footprint and incorporating optical filters to reduce environmental light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate fingerprint sensor is used, then fingerprint sensing function is provided, but device footprint increases and compact design is compromised
Solution Approach 1:
The patent merges the display panel and fingerprint sensor into a single integrated structure. The display panel serves dual functions: visual output and fingerprint sensing. The optical sensor array is integrated underneath the display panel, using the same physical space, thereby eliminating the need for a separate sensor footprint while maintaining compact device design.
Solution Approach 2:
The display panel is designed to perform multiple functions simultaneously. It acts as both the visual display interface and the fingerprint sensing surface. The optical layers and pinhole structure enable the display panel to capture fingerprint patterns while maintaining its primary display function, achieving multi-functionality without increasing device area.
2Measurement precision
If conventional optical imaging is used, then fingerprint capture is achieved, but spatial imaging resolution is insufficient
Solution Approach 1:
The optical system is segmented into distinct functional layers: a pinhole layer with multiple pinholes for light selection, optical layers for light transmission and focusing, and an optical sensor array for detection. This segmentation allows each component to be optimized independently for high-resolution imaging while managing overall system complexity through modular design.
Solution Approach 2:
The pinhole structure acts as an intermediary element between the display panel and the optical sensor array. It selectively transmits light carrying fingerprint information while blocking unwanted light, enabling high spatial resolution imaging. The optical layers serve as intermediaries to focus and direct light onto the sensor array, enhancing imaging quality without requiring complex lens systems.
3Measurement precision
If environmental light is not filtered, then sensor receives all light signals, but imaging accuracy is reduced due to interference
Solution Approach 1:
The patent converts the potential harm of environmental light into a benefit by using the display panel's own emitted light as the illumination source for fingerprint sensing. The optical system is designed to capture light that has interacted with the finger through the display panel, inherently filtering out environmental light interference while using the display's light output for sensing purposes.
Solution Approach 2:
The optical system extracts only the relevant light signals carrying fingerprint information from the total light field. Through the pinhole structure and optical layers, the system selectively transmits light that has passed through the display panel and interacted with the finger, while blocking environmental light, thereby removing harmful interference and improving imaging accuracy.
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 robust, compact, and reliable fingerprint sensing with high spatial imaging resolution, enhancing security by eliminating the need for a separate sensor area and improving user authentication through biometric identification.
Implementation Method 1
an optical sensor array of optical detectors for converting returned light carrying fingerprint information into detector signals representing a fingerprint pattern
Implementation Method 2
a lens unit located between the pinhole layer and the optical sensor array, the lens unit being configured to receive the returned light from the pinhole and to focus the returned light onto the optical sensor array for optical imaging at an enhanced spatial imaging resolution
Implementation Method 3
the optical layers comprise an optically transparent spacer with a refractive index lower than that of the pinhole layer wherein the optically transparent spacer is provided between the pinhole layer and the display panel
Data Source
Figure 1~2A
Figure 2B~2C
Figure 2D~3
AI summary
Devices and optical sensor modules are provided for on-screen optical sensing of fingerprints by using an under-screen optical sensor module that includes a pinhole-lens assembly to enhance the optical imaging performance such optical sensor modules placed under organic light emitting diode (OLED) display modules and other display modules. Techniques for reducing the environmental light in the optical sensing are provided.