Photmetric, Colorimetric Measurement And Evaluation Of White LEDs

LED(Light-Emitting Diode), a new-type light-house after the incandescence, the fluorescent lamp and gas discharge lamp, possesses the advantages that they do not have , such as low power, long life, close structure, small volume, light weight, fine direction, fast response, no radiation and so on. Under the attention of the lighting fields, LED's scopes of application are extending to the lighting field form the indication and display fields owe to the improvement of lighting efficiency, the descending cost and the enrichment of color in the past 40 years. At the same time as the fast development of LEDs, the measurement and the evaluation of the characteristics of LED have got the attention of the international society. In this paper, the new method of the measurement and evaluation about the luminosity and chroma of LED recommended by CIE most recently has been presented. According to the characteristics of the LED with different shape , structures and lighting mechanisms, a plan is introduced and the measurement and analysis has been made through experiment.A new method of the measurement of LEDs according to the other foreign thesis and information is used in the experiment. the methods: first step, assemble and debug the mechanism of measurement, Different application to different lighting-sources. second step, in order to gain the spectra of the lightings, measure directly it by PR-650 SpectraScan Colorimeter, input the measuring datum into the computer by the SpectraWin. third step, data processing.make use of the VC++ program to read directly the data and process them automatically,the result is correlated color temperature(Tcc), general color rendering(Ra) and so on.The emphasis of this experiment is to introduce a way to manufacture white LED by matching the light of red LED, green LED and blue LED, design the device to survey white LED, introduce some methods of measurement and use them to measure the color characteristic of white LEDs. At last we process the date by programming in VC and then acquire the parameters of its color characteristic.The thesis has several main contents: the first part is the introduction composed of the development of traditional lightings, LEDs and the most methods of making white LEDs. the second part includes the theory of the measurement of LEDs. the third part introduces the lighting speciality of LEDs and the measurements of LEDs presently. the new method of the measurement is advanced by CIE. the forth part is the experiment. firstly introduce the measurement implement, measure partingly the white LEDs made up of different quantity of phosphors and the white LEDs matched by different proportion of RGB to obtain their irradiance spectrum, luminous flux, correlated color temperature and so on. the fifth part is the analysis and the summing-up of the experiment. discuss the deviation of the result of the experiment, and analyse the deviation and improve the method of the measurement. The sixth part is the prospect of the LEDs, discussing the difficulty of the development of LEDs.