Angled Light Source for Under-Screen Fingerprint Imaging
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Solution Overview
Problem
Conventional optical fingerprint recognition technologies face challenges in capturing clear images of dry fingers due to low signal-to-noise ratios and limited detection capabilities, especially under-screen scenarios.
Innovation Solution
An image capturing apparatus comprising a light-transmitting cover plate, a light source component, and a lens is designed with a preset angle between the lens axis and the light source normal, allowing non-uniform illumination and positioning the light source outside the lens depth of field, enabling improved signal-to-noise ratios and off-screen detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical fingerprint imaging solution is used, then clear images can be obtained in some cases, but the signal-to-noise ratio is low and clear complete fingerprint images cannot be obtained for dry fingers
Solution Approach 1:
The patent applies local quality by creating non-uniform illumination across the imaging area. The light source is positioned at an angled offset from the optical axis, causing different regions of the fingerprint to receive different light intensities. This localized variation in illumination quality enhances the contrast between ridges and valleys, particularly improving the visibility of fingerprint patterns on dry fingers while maintaining overall image clarity.
Solution Approach 2:
The patent employs asymmetry by deliberately positioning the light source component at an angled offset from the optical axis of the lens, rather than symmetrically aligned. This asymmetric arrangement creates a specific illumination pattern where light strikes the fingerprint at oblique angles, enhancing surface texture visibility and improving the signal-to-noise ratio for fingerprint capture, especially for dry finger conditions.
2Illumination intensity
If the light source is positioned to illuminate the fingerprint, then image capture is enabled, but light source interference reduces the signal-to-noise ratio
Solution Approach 1:
The patent employs asymmetry by deliberately positioning the light source component at an angled offset from the optical axis of the lens, rather than symmetrically aligned. This asymmetric arrangement creates a specific illumination pattern where light strikes the fingerprint at oblique angles, enhancing surface texture visibility and improving the signal-to-noise ratio for fingerprint capture, especially for dry finger conditions.
Solution Approach 2:
The patent applies dimensionality change by moving the light source from the traditional in-plane position (on the optical axis) to an out-of-plane position (angled offset). This spatial repositioning in a different dimensional configuration allows the light to illuminate the fingerprint from an oblique angle, reducing direct interference with the optical path while still providing sufficient illumination, thereby improving the signal-to-noise ratio.
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 enhances image clarity and detection capabilities, particularly for dry fingers, by improving the signal-to-noise ratio and minimizing light source interference, allowing for effective fingerprint imaging even when the finger is not in full contact with the cover plate.
Implementation Method 1
A light generated by the light source component is transmitted through the light-transmitting cover plate
Implementation Method 2
then is scattered by the object to be captured
Implementation Method 3
and the scattered light is focused by the lens to the sensor component
Implementation Method 4
the scattered light is focused by the lens to the sensor component
Data Source
AI summary
An image capturing apparatus and an electronic device are provided. The image capturing apparatus includes: a light-transmitting cover plate, a light source component, a sensor component, and a lens disposed between the light source component and the sensor component. A preset angle is formed between a central axis of the lens and a normal of the light source component. A light generated by the light source component is transmitted through the light-transmitting cover plate, and then is scattered by the object to be captured, and the scattered light is focused by the lens to the sensor component. The light source component is disposed outside of a depth of field of the lens, and the object to be captured is disposed within the depth of field of the lens.