White Tape in Front Light Display for Illumination Uniformity
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Solution Overview
Problem
Electronic devices with light guide-based front lights face issues with illumination uniformity due to changes in refractive index when interacting with nearby materials, leading to distortion and non-uniform light distribution, which affects the user's experience in reading digital content.
Innovation Solution
The use of high reflectivity white tape under and adjacent to the light guide film helps to diffuse and reflect light uniformly, compensating for variations in LED color and improving light beam uniformity by acting as a complementary reflector, thereby enhancing the display's illumination quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light guide film is used for front light illumination, then illumination coverage is improved, but light uniformity deteriorates due to refractive index changes from nearby materials
Solution Approach 1:
A white reflective tape is introduced as an intermediary component between the light guide film and the flexible printed circuit board. This tape acts as a mediator that reflects light back toward the light guide film, compensating for the non-uniform light distribution caused by refractive index changes from the FPC material. The tape's high reflectivity (85-95%) ensures that light is effectively redirected to maintain uniform illumination across the display.
Solution Approach 2:
The white reflective tape utilizes optical color properties to solve the uniformity problem. By using a material with high reflectivity across the visible spectrum, the tape effectively returns light to the light guide film without introducing color distortion. The white color provides broad-spectrum reflection that maintains the natural color output of the LED while addressing the uniformity issue.
2Stability of the object's composition
If materials are placed adjacent to light guide for structural support, then device stability is improved, but light uniformity deteriorates due to refractive index interference
Solution Approach 1:
The white reflective tape serves as an intermediary layer between the light guide film and the flexible printed circuit board. It mediates the optical interaction by reflecting light that would otherwise be lost or distorted due to the FPC's refractive index, thereby maintaining light uniformity while allowing the FPC to provide structural support.
Solution Approach 2:
The patent converts the harmful effect of the FPC's refractive index (which causes light distortion) into a beneficial arrangement. By placing the white reflective tape between the light guide and FPC, the system uses the FPC's presence to stabilize the device while the tape reflects light back to compensate for the refractive index mismatch, turning a potential harm into a controlled feature.
3Ease of manufacture
If LED color variations are present, then manufacturing cost is reduced, but display color accuracy deteriorates
Solution Approach 1:
The white reflective tape provides a broad-spectrum reflection that acts as a color correction element. Because white light contains all visible wavelengths, the tape's high reflectivity across the spectrum helps compensate for LED color variations, ensuring that the final light output appears uniform and accurate despite variations in the LED source.
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 solution ensures a consistent and uniform light output, reducing imperfections and enhancing the reading experience by minimizing dark and bright areas, allowing for improved visibility and color accuracy on the display.
Implementation Method 1
A light guide to control illumination for a front light display
Implementation Method 2
high reflectivity white tape can be used under and adjacent to the light guide to improve overall uniformity of the light beams
Data Source
AI summary
A front light component for electronic devices that include displays for rendering content using a light guide to control illumination for a front light display. A high reflectivity “white” tape is used under and adjacent to the light guide to improve overall uniformity of the light beams. The high reflectivity tape may also be selected to be of a controlled white hue to compensate for variances in color of Light Emitting Diodes (LEDs) where the LED color is slightly off from ideal white. In this way the complementary color of the high reflectivity tape with the color of the LED will cause the output spectrum to be uniform and white. This disclosure also describes techniques for assembling electronic devices in a component stack to provide enhanced display uniformity and improved reading experience.