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Most LED luminaires encounter the problem of color non-uniformity in illumination fields. In order to address the issue, we propose a ripple TIR lens, which can apply to both phosphor-converted LEDs and multicolor LED arrays and achieves good color performance. The ripple TIR lens consists of a collimator and a ripple panel. Simulation results based on a precise phosphor-converted white LED model...
A white LED modeling method is proposed to implement the colorimetric simulation and a novel LED packaging integrated with a specific freeform lens is designed to realize t he high-quality light outp ut. High angula r color uniformity (ACU) is achieved by mixing the central bluish white light and the marginal yellowish white light via the specific freeform lens. Based on the white LED modeling method,...
In this paper, a novel method is proposed to design the first order lens of the packaging module of LEDs. The first order lens consists of a total internal reflector (TIR) and two freeform surfaces. Height of the first order lens is 8mm. The diameter of its maximum caliber is 6mm. Light rays with lager emitting angles will be collimated by TIR, freeform surface 1 will collimate light rays within smaller...
Total Internal Reflection (TIR) lenses are optical components which are used to collimate the light. Desired uniform illumination within a limited beam angle is easy to be achieved by integrating LEDs with TIR lenses. However, most TIR designs do not pay attention to the color uniformity, an increasing important issue for the quality of lighting, and have a considerable dimension, which also limits...
Secondary optics design in the past research only considered illuminance uniformity and ignored luminance uniformity and glare issue, which may result in serious security problem for vehicle drivers. A novel un-symmetric freeform LED lens designed for roadway lighting is proposed. Optical performance of un-symmetric lens will be compared with symmetric lens by optical software. The simulation results...
Light emitting diodes (LEDs) hold the promise for efficient, lightweight and environmental-friendly lighting sources, which is regarded as the next-generation lighting technology. Since so many problems still remain to be solved, this emerging technology has attracted the attention of a large number of researchers. Among several issues frequently discussed in the community, the long-time reliability...
As one type of the chip attachment materials, the solder layer inside the light-emitting diode (LED) packages can not only bond the chips to the substrate tightly, but also play the role of thermal interface material (TIM). Therefore, it makes a great influence on the thermal performance LED packages, especially in high density chip-array LED packaging. The solder layer has become one of the dominant...
Among several materials used in LED packaging, phosphor-filled silicone plays an important role on optical performance and long-time reliability of the module. Many researchers have studied optical properties of phosphor, but few have considered mechanical behavior of phosphor-filled silicone. In this paper, mechanical properties of YAG phosphor-filled silicone are obtained. Tensile tests, which are...
In this paper, we analyze the optical features of different LED packaging types in forward-lighting application. There are generally two packaging types: point source and line source. For the two different packaging types, we introduce several high-efficient supporting opticses in forward-lighting application.
In this study, we first analyse the requirements both in optical and thermal aspects in theory. With the results of theoretical analysis, we design the application specific light emitting diode (LED) packaging (ASLP) with optimized structural parameters and choose appropriate packaging materials. According to this design, several samples are made and tested. The test results show that the LED packaging...
In this study, we firstly analyse the requirements both in optical and thermal fields in theory. With the results of theoretical analysis, we design the application specific light emitting diode (LED) packaging (ASLP) with optimized structure parameters and appropriate packaging materials. According to this design, several samples are made and tested. The test results show that the LED packaging can...
Angular color uniformity (ACU) is essential for LED general lighting. We demonstrated a freeform lens to enhance the ACU of white light-emitting diodes (LEDs) whose phosphor layers were coated by freely dispersed coating processes. The design method of the freeform lens was introduced briefly. Accurate optical models of white LEDs were built. Monte Carlo ray tracing simulation results indicated that...
LED's luminous efficiency increases rapidly in recent years, many novel illumination applications with LEDs are emerging. Based on the analysis of LED's characteristics, our optimization scheme and design methods for LED taxiway lamps are proposed. A novel LED lamp using in navigation of the taxiway of the airport is designed as an example. The simulation results demonstrate that the light utilization...
Light-emitting diodes (LEDs) modules integrated with multi-functions are essential to LED luminaires manufacturers. We demonstrated a 16W application specific LED packaging (ASLP) module integrated with optical, cooling and powering functions for road lighting. A lens design method for extended source was introduced briefly and a borosilicate glass freeform lens for the module was designed according...
Traditional LED packaging always adopts hemisphere lens, although which can ensure high light output efficiency, its light beam is of circular symmetry and non-uniformity. Therefore, LED by traditional packaging cannot be applied in lighting directly and bulky secondary lenses have to be used, which will make the traditional lighting companies difficult to switch to LED lighting and the lamps are...
High power white light emitting diodes (LEDs) have begun to play an important role in many illumination applications due to their excellent performance. In this paper, an effective freeform lens design method for extended light source was suggested briefly for the first time and two compact LED packaging freeform lenses, with the material of polycarbonate (PC) and silicone respectively, were designed...
Optical analysis is critical to the evaluation of an LED MR16 lamp, especially when the lamp is still in its early stage of development and applications and when optimization is needed for making use of unique characteristics of LEDs. In this study, optical research of a 3W LED MR16 lamp was conducted. The experimental results demonstrated that the LED MR16 lamppsilas angle of full width at half intensity...
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