Optical Detector Arrangement Using Light Pipe Assembly
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Solution Overview
Problem
Existing optical detector arrangements for document acceptors, such as currency validators, often require complex hardware configurations and multiple optical detectors to achieve effective light transmission and detection, which can complicate construction, maintenance, and increase costs.
Innovation Solution
A light pipe assembly with internally reflective surfaces and a fresnel lens array is used to direct light from light sources on one side of the document path to optical detectors on the same side, allowing for simplified construction and reduced hardware requirements, while the fresnel lens array anamorphically distorts light to focus a wide area onto fewer detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple optical detectors and complex hardware configurations are used to achieve effective light transmission and detection, then detection reliability is improved, but device complexity increases
Solution Approach 1:
A light pipe assembly acts as an intermediary component to guide and distribute light from a single light source to multiple detection zones. The light pipe with its specific internal geometry (including reflective surfaces and varying cross-sections) enables complex light distribution patterns without requiring multiple light sources or detectors on opposite sides of the document path, thus maintaining detection reliability while reducing overall system complexity
Solution Approach 2:
The light pipe assembly utilizes three-dimensional light propagation and distribution within the pipe structure to achieve multiple detection functions. By manipulating light paths in three dimensions through the pipe's internal geometry, the system can detect multiple document features simultaneously with fewer detectors than would be required in a traditional two-dimensional arrangement
2Measurement precision
If multiple optical detectors are used to detect light transmission, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple detection functions into a single light pipe assembly that can be manufactured as one integrated component. The light pipe incorporates multiple reflective surfaces, varying cross-sections, and light distribution zones all in one piece, reducing the need for multiple separate detectors and associated mounting hardware, thereby lowering manufacturing costs while maintaining detection precision
Solution Approach 2:
The light pipe's cross-sectional area and internal geometry are varied along its length to control light distribution and intensity at different detection zones. By changing the physical parameters of the light pipe structure (cross-section, reflectivity, internal angles), the system achieves precise light control and multiple detection capabilities without requiring multiple expensive detectors
3Measurement precision
If light sources and optical detectors are placed on opposite sides of the document path, then light transmission detection accuracy is improved, but device complexity and maintenance difficulty increase
Solution Approach 1:
The light source and optical detectors are merged into the same side of the document path through the use of the light pipe assembly. The light pipe guides light from the source on one side through the document path and directs the transmitted light to detectors on the same side, simplifying the physical arrangement and making the entire optical system accessible from one side for easier maintenance and alignment
Solution Approach 2:
The light pipe serves as an intermediary that enables the light source and detectors to be positioned on the same side while still achieving accurate transmission detection. It mediates the light path by guiding light through the document and redirecting it to the detectors, maintaining detection accuracy without requiring opposite-side placement
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 simplifies the construction and maintenance of document acceptors, reduces the number of optical detectors needed, and provides customizable light intensity profiles, enhancing detection efficiency and reducing costs by using relatively inexpensive fresnel lenses.
Implementation Method 1
surface features in the light emitting surface. Each surface feature defines a first internally reflective boundary at a far end of the surface feature relative to the first light input port. Light that enters the first input port is directed to the first internally reflective boundaries.
Implementation Method 2
A light pipe assembly with internally reflective surfaces and a fresnel lens array is used to direct light from light sources on one side of the document path to optical detectors on the same side, allowing for simplified construction and reduced hardware requirements, while the fresnel lens array anamorphically distorts light to focus a wide area onto fewer detectors.
Data Source
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AI summary
A sensor arrangement for a banknote validator or other document acceptor using optical transmissive measurements includes at least one light source located on a first side of a document path and arranged to transmit light around the document path to a second side of the document path, the second side being opposite the first side. Optical detectors are located on the first side of the document path and arranged to receive light sent from the light source and passing through the document transport path.