Dome Illumination for Document Verification
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Solution Overview
Problem
Existing document verification methods using passive diffuse illumination suffer from multiple reflections and light discoloration issues, making it difficult to accurately check colored optical features.
Innovation Solution
A document verification device with a dome-shaped cover featuring an active OLED lighting device and an image sensor that provides homogeneous, diffuse illumination without reflections, allowing for efficient detection of light across various wavelength ranges, including infrared and ultraviolet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive diffuse illumination using a dome-shaped cover with diffusely reflective coating is used, then directional reflections on the document surface are reduced, but multiple reflections occur between the document surface and the inner surface of the dome causing light discoloration
Solution Approach 1:
The patent replaces passive optical reflection-based illumination with active light-emitting diodes (LEDs) that directly emit light. This substitution of the illumination mechanism eliminates the multiple reflection path between the document and dome inner surface, as the LEDs are positioned to illuminate the document without requiring reflection from the dome coating.
Solution Approach 2:
The invention extracts and removes the problematic diffuse reflective coating from the dome inner surface, keeping only the structural dome shape. By eliminating the diffusely reflective coating, the source of multiple reflections and light discoloration is removed, while the dome structure still provides its functional benefits.
2Illumination intensity
If a diffusely reflective coating is applied to the inner surface of the dome, then passive diffuse illumination is achieved, but the colored document surface causes the light to be discolored due to multiple reflections
Solution Approach 1:
The patent substitutes passive diffuse reflection-based illumination with active LED illumination. The LEDs emit light directly onto the document surface, providing diffuse illumination through the geometric arrangement of multiple light sources rather than through reflective coating, thereby preserving color accuracy.
Solution Approach 2:
The invention changes the illumination parameters by using multiple LEDs with specific spectral characteristics and positioning them at defined angles relative to the document plane. This parameter optimization enables diffuse illumination while minimizing color distortion through controlled light emission rather than reflection.
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 accurate and efficient verification of optical features by eliminating reflections and maintaining consistent light color, enhancing the ability to authenticate documents with colored surfaces.
Implementation Method 1
the lighting device includes an active OLED film adhered to the inside of the dome-shaped cover
Implementation Method 2
an image sensor for detecting the light reflected by the document in response to the diffuse illumination provided by the lighting device
Data Source
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AI summary
The invention relates to a document inspection device (100) for checking a document (101), comprising: a document holder (103) for receiving the document (101); a dome-shaped cover (105) of the document holder (103), wherein the dome-shaped cover (105) comprises a lighting device (106) which is configured to diffusely illuminate the document (101); and an image sensor (123) for detecting the light reflected by the document (101) in response to the diffuse illumination by means of the lighting device (106).