Surface Light Source Device with Segmented Point Sources
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Solution Overview
Problem
Conventional surface light source devices using point sources, such as LEDs, suffer from luminance unevenness and increased size due to the spacing of point sources, which complicates production and increases manufacturing costs, especially when attempting to mix red, green, and blue lights effectively.
Innovation Solution
A surface light source device with a base member, point-source lines of LEDs arranged in a line, and diffusion transmission members that cover the point-source lines with a substantially equal distance, along with a reflective plate and diffuser plate, to improve light distribution and reduce luminance unevenness, while miniaturizing the light mixing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple point sources are arranged closely to reduce luminance unevenness, then luminance uniformity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The optical waveguide is divided into multiple light introduction portions along its length, with point sources selectively arranged at specific segments rather than uniformly distributed. This segmentation allows luminance uniformity to be improved in critical areas while reducing the total number of point sources, thereby lowering device complexity and manufacturing cost.
Solution Approach 2:
Different regions of the optical waveguide are treated differently by selectively placing point sources at specific light introduction portions. Areas requiring higher luminance uniformity receive more point sources, while other areas use fewer sources. This local differentiation optimizes the balance between luminance uniformity and device complexity.
2Ease of manufacture
If point sources are arranged in a straight line to simplify structure, then ease of manufacture is improved, but luminance unevenness increases
Solution Approach 1:
The straight-line arrangement of point sources is segmented into specific groups positioned at different light introduction portions of the optical waveguide. This segmentation maintains the simplicity of linear arrangement while creating localized variations in light source distribution that improve overall luminance uniformity across the display surface.
3Length of stationary object
If the optical waveguide is made thinner to miniaturize the device, then device size is reduced, but light extraction efficiency decreases
Solution Approach 1:
The point sources are positioned to emit light into the optical waveguide before the light undergoes multiple total internal reflections. By introducing light at specific points along the waveguide length, the system preliminarily distributes light energy to compensate for the reduced extraction efficiency inherent in thinner waveguide structures, thereby maintaining overall light output while achieving miniaturization.
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 effectively minimizes luminance unevenness and reduces the thickness of the light mixing chamber, facilitating easier production, lower manufacturing costs, and improved brightness uniformity, while maintaining high-grade white light production.
Implementation Method 1
a plurality of diffusion transmission members 14 arranged to allow the light fluxes from the point sources to be transmitted in diffusion through the members 14
Implementation Method 2
light emitted from the optical waveguide toward its rear side is reflected by a reflective sheet and brought back into the optical waveguide again
Data Source
AI summary
A surface light source device 1 includes a base member 3 provided with a plurality of point-source lines, each of which has a plurality of point sources 11 arranged in a line, and a plurality of diffuse transmission members 14 for covering the point-source lines. Each of the diffuse transmission members 14 is located while keeping substantially equal distances from the respective point sources 11 at least in a direction perpendicular to each of the point-source lines. Consequently, it is possible to allow light fluxes emitted from the point sources 11 to be transmitted in diffusion through the diffusion transmission members 14.