Papers by Keyword: LED

Abstract: In this study, HfO₂ thin films were deposited onto the Si substrates by RF magnetron sputtering system. After deposition, the HfO₂ thin films were then heated by a furnace thermal annealing process in air and at 400-700^oC. The surface morphologies and crystalline characteristics of the HfO₂ thin films were investigated by using SEM and XRD patterns. The grain sizes and crystalline phases increased with rising annealing temperature. In addition, the SiO₂/HfO₂ distributed bragg reflector (DBR) was used for improving the external quantum efficiency of the GaN-based LEDs. The output power of LEDs with 9-pair SiO₂/HfO₂ DBR and with Ag mirror+6-pair SiO₂/HfO₂ DBR were increased by approximately 10.6% and 7%, respectively, as compared with the LEDs without SiO₂/HfO₂ DBR.

Abstract: The widely applying of LED lighting products promotes the development of smart lighting control system of LED. On the basis of analysis of the existing intelligent lighting control system technology, and with the development of computing and communications as well as cutting-edge technology, this paper puts forward a smart lighting control system of LED based on CPS. Combining practical LED lighting system and CPS theory, hierarchical structure of LED intelligent lighting control system is put forward. And on the basis of the designed system framework, this paper gives the LED intelligent control system based on ZigBee – Wi-Fi structure.

Abstract: A new control scheme with self-adaption is put forward in this paper. The digital control and the analog circuit are combined. A light intensity sensor can be implemented with a photoelectric triode. This sensor makes the self-adaptation control of LED possible. As a result, the light of LED can be adjusted automatically with a PWM chopper according to the ambient brightness. The whole system’s power supply is from a Boost converter which has a high efficiency. In addition, This combination improves the hommization of the system and solves the problems existing incurrent headlamps, unsafe factors are also reduced. The validity of design is verified by experimental results.

Abstract: In order to study the LED light source illumination and the correlated color temperature effect on the human eye visual performance and physiological changes, through the comparative experiments of visual task performances under the different color temperature (3000K low color temperature, 4000K intermediate color temperature) and the different illumination (1145lux high intensity, 500lux middle intensity, 288lux low illumination), study the relationship between the biological effect and visual performance from two aspects of the visual perception performance and the physical efficiency such as blood pressure and pulse. Research indicates that color temperature 3000K or 4000K, intensity of illumination in about 500lux LED light source is suitable to visual task.

Abstract: There are good thermal conductivity, high luminous efficiency in the LEDs with metal substrates, which can effectively solve the problems such as poor heat dissipation、poor reliability of LEDs. The copper substrate LEDs have successfully developed with good performance by SemiLEDs, which indicates the direction of the high-power semiconductor devices for lighting.

Abstract: In this paper, we design a modified insecticides lamp, LED the device by using solar battery as a power supply, high voltage power grid as a hunting tool, through the MCU drive different wavelength of LED strobe. Compared with ordinary insecticides lamp insecticide effect, improved the LED insecticides lamp peculiar four-color stroboscopic technology can be more traps in pests. By sampling clock chip and humidity sensitive resistor, the device will automatically work in spring and summer clear night, met YinYuXue fog and other adverse weather will automatically shut down. The device can be applied to farmland, orchards and other places of a large area of farming, and human nature, energy saving, environmental protection, for the development of LED insecticides lamp provides a new train of thought.

Abstract: Recently, solar LED lighting systems are widely used because of their energy-saving and environment friendly characteristics. But there are also some key problems in current solar LED lighting systems, such as follows: First, the lifetime of lead-acid battery is too short so that the whole system lose efficacy soon; Second, current solar LED lighting systems usually are isolated systems, so its controllability is worse. This paper propose a new solar LED intelligent lighting systems based on Internet of Things and Supercapacitor ,which can tackle these two problems better, so the solar LED intelligent lighting systems will advance applications of solar LED lighting systems.

Abstract: This paper presents the development of hybrid Photovoltaic (PV)-Wind system connected to light emitting diode (LED) street lighting as the load. The aim of this research is to analyze the energy performance from the combination of PV system and wind system which is hybrid system to the LED lamp as the load. In this project, the PV panel and wind turbine used to generate the energy and the output of the energy control by two equipments which are solar charger controller and hybrid charger controller. The output of both PV and wind connected with the battery as storage energy for this system. In this research, the PV system produces the best energy compared to the wind system and it is reliable to charge the battery of the system and supply to the load.

Abstract: ZnO materials have being researched in recent 30 years as a hot topic. ZnO is a third generation of semiconductor, it can be prepared into various forms of films and nanostructures, and they have excellent optical properties, electrical properties and magnetic properties. Because the polar ZnO’s quantum wells have a strong electric field, this will have a great impact on its optical properties. But non-polar ZnO has reduced such a strong electric field, so it greatly improved the luminescent performance. It’s more excellent than polar ZnO in the optical performance. In recent years, non-polar ZnO thin films’ research became increasingly evident. This article summed up the performances, preparations and applications of non-polar ZnO, and there are some suggestions. All of these are good to the further study of non-polar ZnO.

Abstract: Energy-saving lamp will still be a favorite product on the lighting market in the long run. One of the drawbacks of common energy saving lamp is that it cannot be dimmed. Energy is wasted when bright light is not necessary. To promote the idea of energy saving and environmental protection, a plan for the applicability of dimming of energy saving lamp is in urgent need. In this study, we put forward two plans for the dimming of energy saving lamp. Our effort is to make the energy saving lamp adapted to the variety of power frequency and to maximize its smooth dimming as close to that of an incandescent lamp.