A Solar Powered LED Lawn Lamp

As the fourth generation electric light source,light emitting diodes(LEDs)have the avdantages of high luminous efficiency,pollution-free,reliable,no ultraviolet(UV)and infrared(IR)radiation,long lifetime.LED lighting source has gradually replaced other lighting sources such as incandescent lamps,fluorescent lamps and gas discharge lamps.On the other hand,solar energy is the only clean and inexhaustible energy in the world.The most widely used form of solar energy is the solar photovoltaic(PV).Both the LEDs and the PVs have low operation voltage and can be used together perfectly.The solor LED lighting sources combinate with LED and PV are the most energy saving and environmental protection products in the world in recent years,which have excellent performances such as no need external power supply,no electric shock danger,long lifetime,low cost of use and maintain.In this thesis,a solar-powered LED lawn lamb has been designed and fabricated.The lamb is mainly composed of solar cell,control circuit,rechargeable battery,LED lamp and support bracket and other components.Based on the principles of energy efficiency optimization and cost control,the specification of the solar PV board and the capacity of the battery have been matched.The operation current and the lighting duration of the LED has been optimizated by the built-in microchip to match both the capacity of the solar PV and the battery.The uniform illumination and the full use of the light energy of the LED has been achieved by the design of the secondary distribution of light based on the principle of free surface.The designed LED lawn lamb has the following characteristics:(1).Timing function.The lamp can be turned off automatically after 5 hours to save the power of the battery.Because of at this time,most people will stay at home or in sleeping.(2).Two kinds of operati on LED currents function.The LED current will be decreased as the voltage of the battery has been detected lower than setting voltage to expand the duration of the lighting.(3).Secondary distribution light design.Curved surface reflection design has been used as the secondary distribution light toachieve the uniformity of illumination and save the cost of the optical components.(4).Satisfaction of the EMC instructions of the EU,North American and other countries.A lithium-ion battery has been used due to its high cost performance.(5).The main performances of the lamp are listed below:(a).1.2W solar panel power;(b).0.6W LED and 601m luminous flux;(c).rechargeable battery:18650 lithium-ion battery with 2000 mAh capacity and 3.7V Voltage.The prototype of the LED lawn lamp has been fabricated after the processing of design.Then,the performance of the lamp has been measured in detail.The results show that the parameters coincide well with the designed values which mean the lamp has been designed and fabricated sucessfully.In fact,this product has being massed producted and exported for many countries and got good economic benefits.