Optical Sensor Wavelength Multiplexing for Compact Sheet Recognition
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Solution Overview
Problem
Existing banknote recognition systems face challenges in acquiring image data for multiple wavelength bands within a limited time frame due to the need for multiple light-receiving elements, leading to reduced resolution and increased duration of the image acquisition cycle.
Innovation Solution
An optical sensor and sheet recognition unit that uses a controller to control a light source and light receiver with specific light-receiving elements configured to receive multiple wavelength bands at different timings, allowing simultaneous reception of at least two types of light using fewer elements than the number of types of light, thereby optimizing space and improving resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple light-receiving elements are used to receive multiple wavelength bands simultaneously, then the number of types of image data acquired per cycle increases, but the device complexity and space required for arrangement increase
Solution Approach 1:
A single light-receiving element is designed to perform multiple functions by receiving multiple types of light with different wavelength bands through different optical paths. This multi-functional design allows the system to acquire multiple types of image data without requiring separate dedicated light-receiving elements for each wavelength band, thus reducing device complexity while maintaining productivity
Solution Approach 2:
The patent introduces an optical path dimension as a new degree of freedom to distinguish between different wavelength bands. Instead of using spatial separation (multiple light-receiving elements), the system uses temporal and optical path separation, where light from different wavelength bands travels through different optical paths and is received by a single light-receiving element at different timings, effectively adding a dimensional aspect to the detection process
2Measurement precision
If multiple light-receiving elements are used to receive multiple wavelength bands simultaneously, then the resolution of image data improves, but the space required for arrangement increases
Solution Approach 1:
The patent merges the functions of multiple light-receiving elements into a single light-receiving element by combining multiple optical paths. This merging approach allows the system to maintain high resolution image data acquisition while significantly reducing the space required for arrangement, as all wavelength bands are consolidated into one detection point rather than requiring separate detection points for each band
3Device complexity
If light sources for different wavelength bands are lit successively, then the device complexity is reduced, but the period of time for acquiring image data increases
Solution Approach 1:
The system employs periodic action by sequentially activating different light sources for different wavelength bands in a cyclic manner. This periodic illumination pattern, combined with the single light-receiving element receiving light from different optical paths at different timings, allows the system to maintain low device complexity while acquiring multiple types of image data within a limited time frame through structured temporal periodicity
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
The system effectively detects at least three types of light with different wavelength bands using fewer light-receiving elements, reducing the space required for arrangement and increasing the sensitivity and resolution of the image acquisition process.
Implementation Method 1
a light receiver configured to receive a first incident light, a second incident light, and a third incident light travelling from the target and having different wavelength bands
Data Source
AI summary
The optical sensor of the present disclosure includes: a light source configured to emit irradiation light to a target; a light receiver configured to receive a first incident light, a second incident light, and a third incident light travelling from the target and having different wavelength bands; and a controller configured to control the light source. The light receiver includes: a first light-receiving element configured to receive the first incident light and the second incident light and not to receive the third incident light; and a second light-receiving element configured to receive the third incident light and to receive neither the first incident light nor the second incident light.