Dual-Wavelength Illumination Layout for Uniform Image Reading
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Solution Overview
Problem
Existing illumination devices in image reading apparatuses face inefficiencies in irradiation direction and increased manufacturing costs due to complex light guide processing, particularly when using LEDs with different wavelengths.
Innovation Solution
The implementation of a first and second light source, each emitting light of different wavelengths, positioned to intersect their optical axes in an irradiation region, allowing efficient overlapping light without complex light guide processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a plurality of types of LEDs are arranged in two rows in an array to obtain a light amount, then the light amount is improved, but the irradiation directions of the two rows of LED arrays are inclined with respect to the reading target, which lessens the irradiation efficiency to the reading target
Solution Approach 1:
The illumination device divides the light sources into two separate rows, with each row containing LEDs of a specific wavelength. This segmentation allows each row to be optimized for its wavelength while maintaining overall illumination coverage. The first row emits first light and the second row emits second light, both contributing to the total light amount while improving irradiation efficiency through proper angular alignment.
2Stability of the object's composition
If a shape of an emission surface of a light guide is curved to change an emission angle of light emitted from the light guide to uniformly irradiate a reading target with light, then the uniformity of illumination is improved, but the light guide needs to be subjected to complicated processing, which increases the manufacturing cost
Solution Approach 1:
The patent extracts the light guiding function from a single complex light guide structure and distributes it across two separate LED arrays. Each array independently emits light at appropriate angles, eliminating the need for complex curved light guide processing while achieving uniform illumination through the combined effect of both rows.
3Adaptability or versatility
If two types of LEDs are alternately mounted on the same substrate to irradiate light having a plurality of wavelengths, then the wavelength diversity is improved, but the device complexity increases
Solution Approach 1:
The patent segments the wavelength diversity function by separating different wavelength LEDs into distinct rows rather than alternating them on the same substrate. The first row contains LEDs emitting first light and the second row contains LEDs emitting second light. This segmentation simplifies the mounting process and reduces device complexity while maintaining wavelength diversity for comprehensive illumination.
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 enhances irradiation efficiency and maintains uniform illuminance distribution across the irradiation region, reducing manufacturing costs and preventing shadows from occurring.
Implementation Method 1
a first light source that emits first light in a first direction and a second light source that emits second light in a second direction
Implementation Method 2
the first light is overlapped with the second light in the irradiation region
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An illumination device (13) includes a first light source (1311) and a second light source (1312). The first light source (1311) irradiates an irradiation region (221) with a first light in a first direction. The second light source (1312) is disposed opposite to the first light source (1311) to irradiate the irradiation region (221) with a second light in a second direction. The first light is overlapped with the second light in the irradiation region (221). The first light has a wavelength different from the second light.