Backlit Display Panel with Varying Cross-Section Web for Uniform Illumination
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Solution Overview
Problem
Existing information boards with backlighting systems using light-emitting diodes and light-conducting plates face issues with uneven illumination due to the narrow radiation characteristics of diodes, leading to inadequate brightness at the edges, especially in frameless designs intended for safety lighting or pictograms.
Innovation Solution
The design incorporates a light-conducting web with a varying cross-section that increases towards the recess area, allowing for improved light entry and distribution, combined with a reflector to guide light uniformly across the board, ensuring even illumination without direct diode light focusing, and using a metallic reflector for thermal management and concealment of diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light-conducting plate with a central recess and LED lamps is used for backlighting, then the display can be illuminated in a compact design, but the webs between the recess and broad sides are illuminated relatively unevenly with insufficient brightness at the edges
Solution Approach 1:
The web cross-section is varied locally to have a larger cross-sectional area in the region of the broad side compared to the recess region. This local geometric modification allows the web to conduct more light to the broad side edges, compensating for the narrow radiation characteristics of LEDs and achieving uniform illumination without adding complex optical components.
Solution Approach 2:
The cross-sectional area of the web is changed as a parameter along its length, with the web having a larger cross-section near the broad side and a smaller cross-section near the recess. This parameter change optimizes light distribution by providing more light-conducting material where needed, achieving uniform brightness across the display surface.
2Illumination intensity
If LEDs with narrow radiation characteristics are used for backlighting, then the device can be made compact, but sufficient and uniform brightness cannot be ensured up to the edges of the broad side
Solution Approach 1:
The web cross-section is locally optimized with a larger area near the broad side to enhance light conduction to the edges. This local geometric adaptation compensates for the narrow LED radiation pattern, directing sufficient light to the edges without requiring additional LEDs or larger device volume.
Solution Approach 2:
Instead of changing the LED radiation pattern or adding more LEDs, the solution moves to another dimension by varying the web cross-sectional area along its length. This three-dimensional geometric modification of the web provides a new degree of freedom for optimizing light distribution to the edges.
3Illumination intensity
If the web cross-section is increased towards the recess area, then light entry into the web is improved and backlighting is enhanced, but the structural complexity increases
Solution Approach 1:
The web cross-section is varied locally along its length, with the larger cross-section positioned near the broad side where light conduction is most needed. This local geometric optimization improves web illumination and edge brightness without requiring complex overall web structures or additional components.
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 provides a frameless information board with uniform and enhanced backlighting, preventing discernible brightness differences and allowing for compact, low-cost production while maintaining structural simplicity and stability.
Implementation Method 1
US2008/0049168A1 mentions increasing the optical coupling of the LED inserted in a recess in the light-guiding plate by total reflection at the webs of the light-guiding plate
Data Source
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AI summary
The panel (1) has a backlit display (2), and a photoconductive plate (5) for back-lighting of the display. The plate forms a recess (7), and a LED (3) is accommodated in the recess. The LED is optically connected with the plate over a recess surface (14), where a cross-section of a rod is enlarged in the direction of the recess surface over the course of a rod edge that is turned towards the recess. A metallic reflector (11) is connected to the rod, and the LED is fastened to a printed circuit board (4). A stopper (21) positions the LED in the recess.