Rod Lens Light-Shielding Structure for Precise Illumination Control
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Solution Overview
Problem
Conventional light source units with rod lenses struggle to precisely control illumination regions and maintain desired illuminance as the number of light-emitting elements increases, leading to stray light and reduced illumination efficiency.
Innovation Solution
A light source unit comprising a first and second light-emitting element, a rod lens with a smaller second end surface area than the first, and a light-shielding body that covers the side surface of the rod lens, featuring a protruding tip and varying opening areas to absorb stray light and control illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of light-emitting elements is increased to obtain the desired illuminance and the rod lens is accordingly enlarged, then the illuminance is improved, but the light may stray from the desired illumination region
Solution Approach 1:
The patent extracts and removes the harmful stray light generated by the enlarged rod lens through a light-shielding body. The light-shielding body is positioned to block light that escapes from the side surface of the rod lens, separating the useful illumination from the harmful stray light and preventing it from reaching the illumination region.
Solution Approach 2:
The light-shielding body acts as an intermediary element between the rod lens and the illumination region. It mediates the light paths by blocking stray light while allowing the intended illumination to pass through, thus resolving the contradiction between maintaining illuminance and preventing stray light.
2Illumination intensity
If the rod lens is enlarged to accommodate more light-emitting elements, then the illuminance is improved, but the precision of illumination region control deteriorates
Solution Approach 1:
The light-shielding body extracts and removes the unwanted stray light paths that become more prominent with larger rod lenses. By selectively blocking these paths, the system maintains precise control over the illumination region even as the rod lens size increases to accommodate more light-emitting elements.
3Manufacturing precision
If a light-shielding body is added to block stray light, then the illumination region control is improved, but the device complexity increases
Solution Approach 1:
The light-shielding body is designed with local quality variations - the tip portion has a different structure than the main body, with a specific opening area ratio (0.1-0.5) that optimizes stray light blocking while maintaining simplicity. This localized design approach improves illumination control without unnecessarily increasing overall device complexity.
4Object-generated harmful factors
If the light-shielding body tip protrudes further than the second end surface, then the stray light blocking is improved, but the device complexity increases
Solution Approach 1:
The light-shielding body features a localized protruding tip portion with specific geometric characteristics (opening area ratio between 0.1-0.5) that provides enhanced stray light blocking capability. This localized structural variation achieves improved performance without requiring complex overall redesign of the light-shielding body.
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 solution enables precise control of the illumination region, reduces stray light, and maintains desired illuminance by absorbing light emitted from the side surface of the rod lens, enhancing light extraction efficiency and contrast between the desired illumination area and external regions.
Implementation Method 1
The light that enters the rod lens repeats total internal reflections and is emitted from a second end surface of the rod lens
Data Source
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AI summary
A light source unit includes light-emitting elements, a light-shielding body, and a rod lens including a first end surface, a second end surface, and a side surface. The light-shielding body is separated from the side surface, covers the side surface, includes an opening exposing at least a portion of the second end surface, and includes a tip protruding further than the second end surface in a first direction from the first end surface toward the second end surface. A first plane crosses the first direction and is at the same first-direction position as the tip. A second plane crosses the first direction and is at the same position as the second end surface or between the tip and second end surface in the first direction. A first surface area of the opening at the first plane is greater than a second surface area of the opening at the second plane.