Research On The High Efficiency Edge-lighting LED Flat Panel Light With No LGP

In the new period, the nervous of energy resources has become a focus ofparticular concern. And LED light fixtures are environmental-friendly andenergy-saving green, for use in lighting products, that has become ever more activein the indoor lighting market. The Edge-lighting LED flat panel light with light guideplate (LGP) brings soft and high-brightness light to large area lighting. It still existingmany problems in low extraction efficiency and high manufacturing price, etc. In thisdissertation we study a new kind of LED flat panel light which is rear projection andno LGP, and in order to improve the luminous efficiency we have optimized itsstructure, backlight, diffuser and drive circuit.Based on the concept of architectural design and People’s Daily lighting habits,this paper propose a new rear projection structure of LED flat panel light which iswindow type structure and without LGP. Multiple panes of it are adopted to realizelarge area lighting, the divergent beam which come from the edge of LED lightsource converged by cylindrical lens and the light grazing incidence in a light panel isa transmission-type diffusion plate. Due to the light is no loss of multiple reflections,the extraction efficiency of LED flat panel light with no LGP is higher than generalLED flat panel light, also it is high efficiency, low cost, thin and light weight. TheOptimization of backlight structure was designed. Cylindrical lens are used to makethe divergent beam which come from the edge of LED light source convergent, andthe method of gazing and superposition are used to realize uniform illumination of thelight pane. Based on the basic principle of photometry and geometrical optics, Theintensity distributions impacted by the distance between the LED arrays and the LEDprojection angle or the space between LEDs are discussed. Optical simulations of theLED flat panel light designed based on squared figure Value method, combined withTracePro are performed to realize parameter optimization. The Radiator of thewall-hung LED flat panel light is designed on the basis of "chimney effect"."chimney" structure is formed by the cavity of the framework of LED flat panel light,According to the principle of hot air density is small, easy floating, it can make the light cooling by rapidly rising the air in tube which behind LED strip flow, add wavystrips to the tube behind LED strip flow, that can significantly accelerate the air on theback of the LED lamp which improving heat emission efficiency. A low-power LEDdriven circuit is designed which is suitable for LED flat panel light. New attachmentstructure and drive mode is used, that LED driving circuit doesn’t have energydissipation components, such as resistances and power tubes. And capacitances areused to realize the current limit effect under AC drive, so the power consumption ofLED driving source can be reduced.A grazing incidence diffuser with double-sided triangular prism arrays isresearched, which is suitable for edge-lighting LED flat panel light without lightguide plate. Based on Fresnel equations, the anti-reflection principles of triangularprism arrays are analyzed. The influence of parameters of the triangular prism arrays,i.e. the ratio of depth to width and the bottom width, on the diffuser transmittance isinvestigated by using the simulation of ray tracing software TracePro. Simulationsreveal that the transmittance of entry surface increases with the ratio of depth to width,both for PMMA and PC. The transmittance achieves the maximum while the ratio ofdepth to width is about0.5, and keeps invariant when the ratio increased. Thetransmittance of exit surface decreases when the ratio of depth to width is close to0.5,because of the light has been total reflected twice in the diffuser. The results showthat the transmittance of grazing incident ray can be up to93%in the optimizeddiffuser. Molds is making by the laser marking machine on the optimized parametersof the triangular prism arrays. The PMMA diffuser with double-sided triangular prismarrays is manufactured by hot-press approach. The uniformity, luminous efficiencyand luminance distribution of the diffuser has been test. The test result agrees wellwith the simulations result.