• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.118-123
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• 2007

The emitting structure of multi-channel-type flat fluorescent lamps (FFLs) combined by a lenticular-lens-patterned diffuser plate was optimized by the ray tracing technique. The optimal parameters such as the distance between the channels of the FFL and the distance between the FFL and the diffuser plate were suggested from the viewpoint of the luminance uniformity. The best luminance uniformity, which was higher than 90%, was obtained at the channel distance of 4 mm and the distance of 12.5 mm between the FFL and the patterned diffuser plate.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.243-244
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• 2006

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1066-1067
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• 2004

New diffuser film for LCD backlight is developed. A diffuser film was manufactured through coating UV curable monomer on a plastic film. The diffuser layer coated on plastic film showed excellent optical transmittance.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.251-255
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• 2014

A fiber diffuser sheet based on poly (ethylene naphthalate) (PEN) and poly (methylpentene) (PMP) has shown potential for liquid crystal display backlight units, but these materials have an interfacial adhesion problem. To improve the interfacial adhesion between the fibers and matrix components, we have proposed the use of amorphous poly (cyclohexane-1,4-dimethylene terephthalate) (Tritan) instead of PEN. Furthermore, the fabrication processes have been optimized and simplified to improve the optical and mechanical properties of the sheet. As a result, the most effective fiber content for achieving the best haze characteristics of a sample consisting of Tritan and PMP has been identified.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.31-36
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• 2011

CF(Circular Fresnel) POF(Plastic Optical Fiber) daylighting system is a beam daylighting system utilizing solar direct beam radiation. In this study, a CF POF daylighting system has been introduced, developed and applied to KIER test buildings. The CF POF daylighting system consists of three parts: light collector, light transmitter and light diffuser. The light collector includes a Circular Fresnel lens focusing solar direct illuminance by sun tracking. The light transmitter contains the POF cable which has light transmission loss of 4.5% per meter. The light diffuser has about 80% diffuser efficiency. This study aims to evaluate of POF daylighting system performance. At the results of a CFPOF system performance evaluation, the theoretical CFPOF system efficiency was 41.9% and the actual CFPOF system efficiency at the KIER test building was 37.5%. The difference was due partly to the connecting efficiency.

• Korean Journal of Materials Research
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• v.22 no.12
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• pp.650-657
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• 2012

For the purpose of improving the durability problem, translucent opal glass was fabricated as a substitute for the polycarbonate diffuser of LED lighting. Calcium phosphate was used as an opacifier of opal glass and melted in an electric furnace. The opaque effect was identified according to the change of the cooling procedure. As results, translucent opal glass was obtained by the melting of a batch with a composition of 3.8% calcium phosphate at $1550^{\circ}C$ for 2 hrs and then the cooling of the material in the furnace. For the cooling condition of the glass sample, HTCG (High Temperature Cooled Glass) was found to have better optical properties than LTAG (Low Temperature Annealed Glass). It had excellent optical properties for a diffuser of LED lighting, with no dazzling from direct light due to its high haze value of over 99% and low parallel transmittance value of under 1%. For the thermal properties, it had an expressed thermal expansion coefficient of $5.7{\times}10^{-6}/^{\circ}C$ and a softening point of $876^{\circ}C$; it also had good thermal properties such as good thermal shock resistance and was easy to apply to the general manufacturing process in the forming of glass tubes and bulbs. Therefore, it is concluded that this translucent opal glass can be used as a glass diffuser material for LED lighting with high heat resistance and high durability; this material is suitable as a substitute for polycarbonate diffusers.

• Journal of the Semiconductor & Display Technology
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• v.11 no.1
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• pp.21-27
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• 2012

The optical diffuser for direct-lit LED backlight unit was prepared by using extrusion compounding followed by thermoforming process. Poly(methyl methacrylate) (PMMA) with superior optical characteristics and polycarbonate (PC) with good thermal property were used as base resins, and crosslinked polystyrene (PS) and PMMA beads as diffusing agents were incorporated into resin matrix to derive light scattering and diffusing action. In the compounded plate, the diffusing beads were observed to be dispersed uniformly and distinctly in the continuous phase. The inclusion of polymeric beads up to 3 wt% substantially enhanced the optical characteristics such as luminance, luminance uniformity, haze for the diffuser. Two different diffusers of PC and PMMA-based compound with various compositions were compared in terms of measured optical, thermal, and mechanical properties, which would be expected to be utilized for the industrial application of LED backlight unit.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.86-87
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• 2001

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.26-33
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• 2015

Secondary optical system designed for LED bulb which emits light in all directions was simulated with Energy Star standards. Components of the optical system were LED light source, the cover of the LED bulb and reflector which is to confirm the diffuser plate and LightTools software was used to design the illumination optics. The main points of the secondary optical system design are the location of the LED light source, the shape of the LED bulb cover, the location of the reflection plate, and the scattering properties of the diffusing plate. Mechanism of the LED bulb is that the light emitted from the light source move on to the backward after reflected by the coated light cover from the inside and then the reflected light is scattered by the diffuser plate. The LED bulb was designed to satisfy the standard light distribution and color specifications of the Energy Star(IES LM-79-08).

• Elastomers and Composites
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• v.50 no.1
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• pp.49-54
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• 2015

Dynamically vulcanized PMMA/ACM (80 wt%/20 wt%) blend using DCP as a curing agent was prepared using internal mixer. The morphology, mechanical properties, optical properties, melt viscosity and die swell were characterized by using FE-SEM, tensile test, Izod impact test, dynamic mechanical analysis, ARES and capillary rheometer, respectively. The blends show a phase-separated morphology in which ACM are dispersed in PMMA matrix. Dynamically vulcanized blend exhibits higher mechanical properties, higher melt viscosity, and die swell as compared to simple blend. And, the dynamically vulcanized blend showed total transmittance of more than 75% and haze of higher than 90%, which enable it to find potential applications to fabricate an optical diffuser by extrusion process.