Light Guide Element Homogeneous Facial Illumination
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Solution Overview
Problem
Conventional facial image capture systems in kiosk or office environments face challenges in achieving homogeneous illumination and minimizing reflections from glasses, leading to compromised image quality and user acceptance.
Innovation Solution
A detection device with a light-guiding element having a microstructured surface and a luminous area, coupled with a light source, provides homogeneous illumination and reduces reflections by adjusting light emission based on detected reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional studio lighting setups are used to achieve homogeneous illumination and minimize reflections, then image quality is improved, but device size and complexity increase
Solution Approach 1:
A light guide element is introduced as an intermediary between the light source and the face. This light guide transmits and distributes light uniformly across the detection volume, eliminating the need for complex multi-angle lighting arrangements while achieving homogeneous illumination and minimizing reflections.
2Manufacturing precision
If multiple studio lights are positioned at specific angles to eliminate reflections, then facial image quality is improved, but the space required for the setup increases
Solution Approach 1:
The light guide element serves as a mediator that transmits light from a compact source through its internal structure (with surface recesses for light distribution) to illuminate the face uniformly. This eliminates the need for multiple lights positioned at specific angles, significantly reducing the space required for the setup while maintaining reflection-minimized image quality.
3Illumination intensity
If light sources are positioned to illuminate the face obliquely from below, then illumination coverage is improved, but glare and shadows are introduced
Solution Approach 1:
The light guide element acts as an intermediary that distributes light uniformly across the detection volume without creating harsh shadows or glare. The light is transmitted through the light guide's structure and emitted towards the face in a controlled manner, providing comprehensive illumination coverage while avoiding the harmful effects of direct oblique lighting.
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 high-quality, shadow-free facial images across various body sizes, improving user acceptance and reducing errors in facial image capture.
Implementation Method 1
a light guide element with a luminous surface, wherein the light source is configured to generate light and couple the generated light into the light guide element, and wherein the light guide element is configured to emit the coupled light via the luminous surface in the direction of the detection volume
Implementation Method 2
The light guide element can have a surface with a plurality of surface recesses for reflecting the coupled light within the light guide element
Implementation Method 3
The light guide element can have a surface with a plurality of surface recesses for reflecting the coupled light within the light guide element, thereby achieving homogeneous emission of light across the illuminating surface
Data Source
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AI summary
The invention relates to a sensing device (100) for capturing a facial image of a person. The person's face is arranged in a sensing volume. The sensing device (100) comprises an illuminating apparatus (101), which is designed to illuminate the person's face in the sensing volume. The illuminating apparatus (101) comprises a light source and a light-guiding element having a lighting surface, wherein the light source is designed to produce light and to input the produced light into the light-guiding element, and wherein the light-guiding element is designed to emit the input light toward the sensing volume via the lighting surface in order to homogeneously illuminate the person's face. The sensing device (100) also comprises an image camera (103), which is designed to capture an image of the person's face in the sensing volume in order to capture the facial image of the person.