Line Light Source UV Visible Filters
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Solution Overview
Problem
Conventional line light sources face challenges in accommodating both visible/infrared and UV light source portions due to size constraints, leading to reduced accuracy in authenticity verification and uneven light emission, which affects the recognition of paper sheets.
Innovation Solution
The line light source is designed with separate light source portions for visible/infrared and UV light at each end of the light guide, using filters to prevent fluorescence and ensure even light distribution, allowing both types of light sources to be integrated without reducing the amount of light emitted towards the paper sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If both visible/infrared light source portion and UV light source portion are set at one end of the light guide, then the structure is compact, but the UV light source portion becomes too large and cannot be accommodated
Solution Approach 1:
The light source portions are segmented and distributed to different ends of the light guide. The visible/infrared light source portion is placed at one end while the UV light source portion is placed at the other end, allowing each to have adequate space without compromising overall compactness.
Solution Approach 2:
The arrangement transitions from a one-dimensional concentration at one end to a two-dimensional distribution along the length of the light guide, utilizing the longitudinal dimension to accommodate both light source portions with appropriate spacing.
2Ease of operation
If UV light source portion is placed at one end of the light guide, then visible/infrared light source can be placed nearby, but fluorescence is emitted from base members and end surfaces reducing verification accuracy
Solution Approach 1:
The harmful fluorescence emission is extracted and removed from the system by strategically positioning the UV light source at the opposite end from the visible/infrared light source, preventing UV-induced fluorescence from interfering with the detection of authentic features.
Solution Approach 2:
The light guide itself acts as an intermediary that separates the UV and visible/infrared light paths, preventing direct interaction between UV light and the base members of the visible/infrared light source portion, thereby eliminating fluorescence interference.
3Measurement precision
If light source portions are distributed at both ends of the light guide, then fluorescence interference is reduced, but the amount of light emitted toward the paper sheet may be reduced
Solution Approach 1:
The light guide is designed with different optical properties at different locations: the central region optimizes for light transmission to the paper sheet while the end regions manage the light source interactions. This local differentiation allows both ends to have light sources while maintaining sufficient illumination intensity.
Solution Approach 2:
The optical parameters of the light guide, such as refractive index and absorption coefficient, are optimized to compensate for the distributed light source configuration, ensuring that sufficient light reaches the paper sheet despite the extended arrangement of light sources at both ends.
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 accurate verification of paper sheet authenticity and ensures stable, uniform illumination, preventing fluorescence interference and maintaining sufficient light emission for effective reading.
Implementation Method 1
the light emitted from the light source portion into the light guide through one end is diffused and refracted by the light diffusion pattern and partially emitted from one side surface of the light guide toward the paper sheet
Implementation Method 2
the light emitted from the light source portion into the light guide through one end is diffused and refracted by the light diffusion pattern
Implementation Method 3
a first filter 7 transmits the UV light and reflects or absorbs the visible light or the light in the wavelength range from the visible light to the infrared light
Implementation Method 4
the UV light is reflected by the second filter 6 and returned to the light guide
Implementation Method 5
The UV light emitted from the first light source portion 4 to the light guide enters into the light guide through the first end surface 1e
Implementation Method 6
the UV light emitted from the UV light emitting light source portion and entered into the one end surface is passed through the other end surface of the light guide and illuminates the other light source portion, fluorescence is also secondarily emitted
Data Source
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AI summary
In a line light source including light source portions (3, 4) at both ends of a light guide (1), an amount of light emitted from one side surface (1d) of the light guide (1) toward a paper sheet is prevented from being reduced. The line light source includes the light guide (1) extending in a longitudinal direction (L) and made of resin that transmits a light from a UV light to a visible light; the first light source portion (4) disposed at a first end surface (1f) of the light guide (1) to emit a UV light; the second light source portion (3) disposed at a second end surface (1e) of the light guide (1) to emit a visible light; a second filter (6) disposed between the second end surface (1e) of the light guide (1) and the second light source portion (3) to transmit the visible light and reflect the UV light; and a first filter (7) disposed between the first end surface (1f) of the light guide (1) and the first light source portion (4) to transmit the UV light and block the visible light or a light in the wavelength range from the visible light to the infrared light. The light emitted from the second light source portion (3), or the light emitted from the first light source portion (4) is emitted from the light exit surface (1d) of the light guide (1).