| Summary: | 碩士 === 國立雲林科技大學 === 電子工程系 === 107 === Light emitting diodes had attracted serious concern because of the booming lighting market. Not only to the application of displays, but light emitting diodes were also used in electro-optical devices such as flashlight, outdoor signage board, brake light and desk lamp. Owing to it's high luminous efficacy and low driving voltage. Light emitting diodes with high luminous flux were quite expected in the scientific research.
Light emitting diodes had a great potential in the application of electro-optical components owing to the low driving voltage. From the literature, we could find that infrared and thermography were used in a lot of fields. But infrared was not used as the source of displays yet. In thesis a thermography simulator was designed. By changing the light intensity of light emitting diodes in the array through the system program, it could simulate the real thermography brightness and regulation. The possible thermography simulated target maybe the thermal source of military devices for the purpose of military operation. Using this type of thermography simulator, enemy could be cheated into attacking the fake thermography of the engine of fighter aircraft and tank.
In this research, we changed the duty cycle ratio and flickering time of driving program in light emitting diodes. Finally, we explored the results of thermography simulation and observed the influence of light intensity from different duty cycle ratio and different flicker time.
In the experiment, we observed the varivations of light intensity in different temperature by using iron club to be the thermal source. The relationship of heat temperature and light intensity was a function relation. We modified the duty cycle of pulse width modulation to observe the variations of light intensity. The results showed that brightness regulation by pulse width modulation was better than different flicker time and the more of the duty cycle the more increase of the light intensity. The light intensity of light emitting diode could meet the design demand when the duty cycle of pulse width modulation was at 25.0%, 53.1% and 85.9% for each type of light emitting diodes.
Keywords: Light Emitting Diodes, Infrared, Thermography
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