Surface Light Source Device with Recessed LED and Optical Film
Solution Overview
Problem
Conventional surface light source devices suffer from luminous unevenness and inefficiencies in light distribution, leading to insufficient display quality and in-plane luminance uniformity due to conic recess designs and incomplete light diffusion.
Innovation Solution
A surface light source device featuring a housing with a light guiding plate and a recess for the light source, incorporating a reflection sheet with specific total light transmittance properties to adjust and diffuse light, ensuring even luminance and improved display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conic recess is provided to insert the light source, then the light source can be fixed on the back face of the light guiding plate, but the width of the recess becomes narrower toward the far side, causing luminous unevenness and reducing light efficiency
Solution Approach 1:
The patent applies local quality by providing a reflective coating specifically on the side wall face of the recess and using a light quantity adjusting film with specific optical properties at the bottom of the recess. This localized treatment of different regions (side wall vs. bottom) with different optical functions (reflection vs. diffusion/attenuation) resolves the contradiction by maintaining uniform light distribution while preserving the conic recess structure for easy light source insertion
2Illumination intensity
If a light reflection surface is formed ahead of the light source to shield direct light, then luminous distribution can be made uniform, but direct light toward ahead is partially transmitted, causing luminous unevenness ahead of the light source
Solution Approach 1:
The patent applies parameter changes by carefully controlling the optical properties (transmittance, reflectance, diffusion characteristics) of the light quantity adjusting film to satisfy specific mathematical relationships. By adjusting these optical parameters within defined ranges, the system achieves complete light diffusion while preventing direct light transmission, thereby resolving the contradiction between luminous distribution uniformity and energy loss
3Illumination intensity
If a pattern or light shielding structure is used to adjust light quantity, then luminance can be made uniform, but the light is not fully diffused, entailing luminous unevenness ahead of the light source
Solution Approach 1:
The patent applies the taking out principle by extracting the light diffusion function from complex pattern structures and concentrating it in a simple light quantity adjusting film with specific optical properties. This film completely diffuses light without requiring intricate patterns or shielding structures, thereby resolving the contradiction between luminance uniformity and device complexity while ensuring complete light diffusion
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 enhances light efficiency, achieves uniform in-plane luminance, and provides sufficient display quality by effectively diffusing and reflecting light, reducing luminous unevenness and color irregularities.
Implementation Method 1
a reflection sheet having a reflection function for reflecting the light from the light source
Implementation Method 2
a transmission function in which a total light transmittance t satisfies t≧πr2 cos θ/{(1−cos θ)(S−πr2)}
Implementation Method 3
a light guiding plate arranged at a position so as to cover the opening portion and the light source
Implementation Method 4
reflected light is guided from a side wall face of the light source insertion section into an inside of the light guiding plate
Data Source
AI summary
A surface light source device according to the invention includes a housing having an opening portion on at least one face, an LED light source held by one face of the housing opposing the opening portion, and a light guiding plate arranged at a position so as to cover the opening portion and the LED light source. The light guiding plate includes a recess provided at a position corresponding to the LED light source for storing a part of the LED light source. A light quantity adjusting means is provided at a bottom part of the recess for adjusting light from the LED light source. The light quantity adjusting means includes a reflection sheet having a reflection function and a transmission function in which a total light transmittance t satisfies t≧πr2 cos θ/{(1−cos θ)(S−πr2)}, supposing that an average radius is defined as r, a distance from the LED light source is defined as H, a light-emitting area of the LED light source is defined as S, and a total light quantity is defined as L.