Image Sensor Unit for Multi-Ink Detection
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Solution Overview
Problem
Existing image sensor units struggle to detect substances other than fluorescent ink reactive to ultraviolet light due to wavelength limitations, and they are not configured to handle both ultraviolet and visible light sources effectively for reading targets like valuable paper with multiple ink types.
Innovation Solution
An image sensor unit is designed with a first light source emitting ultraviolet light, a second light source emitting visible light, and includes visible and ultraviolet light cut filters to isolate and block unwanted wavelengths, allowing for low-noise detection of fluorescence light and stable detection of non-ultraviolet wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a first filter is arranged on the emission side of ultraviolet light-type LEDs to filter out non-ultraviolet light, then the ability to detect fluorescent substance is improved, but the device cannot detect substances other than fluorescent substance having fluorescent reactivity to ultraviolet light
Solution Approach 1:
The patent divides the optical path into separate channels: one for ultraviolet light to detect fluorescent substances, and another for visible light to detect non-fluorescent substances. This segmentation allows each channel to be optimized for its specific detection purpose without interference from the other wavelength range
Solution Approach 2:
The image sensor unit is designed to perform multiple detection functions simultaneously: it can detect both fluorescent substances (using ultraviolet light) and non-fluorescent substances (using visible light). The sensor head acts as a universal detection device that adapts to different ink types based on the light source and filter configuration
2Adaptability or versatility
If both ultraviolet light and visible light are used to irradiate the reading target, then the detection of multiple ink types is enabled, but the fluorescent light detection is contaminated by reflected ultraviolet light and non-ultraviolet light components
Solution Approach 1:
The patent introduces optical filters as intermediary elements that selectively transmit or block specific wavelength ranges. The first filter (arranged on the ultraviolet light emission side) blocks non-ultraviolet light from reaching the sensor, while the second filter (arranged on the optical path between medium and sensor) blocks ultraviolet light. This intermediary filtering mechanism allows clean separation of fluorescence signal from reflected light interference
Solution Approach 2:
Different regions of the optical system are assigned different filtering characteristics: the ultraviolet path includes filters optimized for fluorescence detection, while the visible light path includes filters optimized for non-fluorescent substance detection. Each local region of the optical system has quality properties tailored to its specific detection function
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 enables low-noise detection of fluorescence light from ultraviolet light and stable detection of non-ultraviolet wavelengths, improving the ability to identify various ink types on valuable paper.
Implementation Method 1
a visible light cut filter arranged between the first light source and the first light guide and blocking the light including visible light having wavelengths longer than those of ultraviolet light
Implementation Method 2
an ultraviolet light cut filter arranged between the lens body and the line sensor and blocking ultraviolet light
Implementation Method 3
a lens body condensing light generated on the reading target by the light radiated from the first light guide and the light radiated from the second light guide
Implementation Method 4
a columnar first light guide guiding the light emitted by the first light source from both end surfaces and radiating, from a side surface, the light toward the reading target
Implementation Method 5
a columnar second light guide guiding the light emitted by the second light source from both end surfaces and radiating, from a side surface, the light toward the reading target
Implementation Method 6
the irradiation by ultraviolet light leads to occurrence on the valuable paper of the fluorescence reaction
Data Source
AI summary
An image sensor unit includes: a visible light cut filter that is arranged between a first light source and a first light guide and blocks light including visible light having wavelengths longer than those of ultraviolet light; a lens body that condenses light generated on a reading target by light radiated from the first light guide and light radiated from a second light guide; a line sensor that receives the light condensed by the lens body; and an ultraviolet light cut filter arranged between the lens body and the line sensor and blocks ultraviolet light.