Edge-lit light guide panels (LGPs) with micropatterned surfaces represent a new technology for developing small- and medium-sized illumination sources for application such as automotive, residential lighting, and advertising displays. The shape, density, and spatial distribution of the micro-optical structures (MOSs) imprinted on the transparent LGP must be selected to achieve high brightness and uniform luminance over the active surface. We examine how round-tip cylindrical MOSs fabricated by precision micromilling can be used to create patterned surfaces on low-cost transparent polymethyl-methacrylate substrates for high-intensity illumination applications. The impact of varying the number, pitch, spatial distribution, and depth of the optical microstructures on lighting performance is initially investigated using LightTools™ simulation software. To illustrate the microfabrication process, several 100×100×6 mm 3 LGP prototypes are constructed and tested. The prototypes include an “optimized” array of MOSs that exhibit near-uniform illumination (approximately 89%) across its active light-emitting surface. Although the average illumination was 7.3% less than the value predicted from numerical simulation, it demonstrates how LGPs can be created using micromilling operations. Customized MOS arrays with a bright rectangular pattern near the center of the panel and a sequence of MOSs that illuminate a predefined logo are also presented.
Edge-lit backlighting has been used extensively for a variety of small and medium-sized liquid crystal displays (LCDs).
The shape, density and spatial distribution pattern of the micro-optical elements imprinted on the surface of the flat
light-guide panel (LGP) are often "optimized" to improve the overall brightness and luminance uniformity. A similar
concept can be used to develop interior convenience lighting panels and exterior tail lamps for automotive applications.
However, costly diffusive sheeting and brightness enhancement films are not be considered for these applications
because absolute luminance uniformity and the minimization of Moiré fringe effects are not significant factors in
assessing quality of automotive lighting. A new design concept that involves micromilling cylindrical micro-optical
elements on optically transparent plastic substrates is described in this paper. The variable parameter that controls
illumination over the active regions of the panel is the depth of the individual cylindrical micro-optical elements.
LightTools™ is the optical simulation tool used to explore how changing the micro-optical element depth can alter the
local and global luminance. Numerical simulation and microfabrication experiments are performed on several
(100mmx100mmx6mm) polymethylmethacrylate (PMMA) test samples in order to verify the illumination behavior.
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