| Vision is the most important means of obtaining information.With the rapid development of mobile communication technology,the requirements for display technology are getting higher and higher.Light Emitting Diode Microdisplay is considered as the display technology of the future and has attracted much attention from the industry.Microdisplay refers to a display technology with a diagonal size of less than 1 inch and a resolution of higher than 1000 PPI(pixels per inch),which is different from mobile phones,laptops and televisions that we watch every day.LED has the advantages of low working voltage,high brightness and efficiency,fast response rate,compact structure etc.,and is currently widely used in the field of lighting.When the size of the LED unit is reduced to the order of micrometers,that is Micro Pixel LED,it can be used to make a high-performance display,which is superior to the current mainstream liquid crystal display technology.This dissertation has carried out systematic research work around the application of Micro Pixel LED in the display field.The main contents are as follows,1.The system design of light-emitting diode micro-display,such as the design of light-emitting pixels and corresponding drive circuits;design of device manufacturing processes,preparation and improvement of photo masks.2.Introduction of the main equipment for the fabrication process of LED micro display devices,and development of a green LED Microdisplay with diagonal size of 0.42 inch(9.6 mm by 5.4 mm)and resolution of 480×270(1/16 HD),investigation and evaluation of the sapphire substrate used,photolithography,etching,and coating of GaN light-emitting diode epitaxial wafers,and device packaging.3.Design and manufacture of the full-screen lighting detection equipment before the bonding process.The main design ideas include:sequentially lighting up 129,600 pixels on each die on the arrayed device,using single-sided printed double-layer lay out PCB board double wiring and a flat metal probe method as a conductive stage for pixel array,and then assembling these parts into a set of automatic optical detection system,that is AOI system.The inspection on the surface defects of the LED micro display device was implemented.4.Optoelectric characterizations of the green LED micro display are as follows:the turn-on voltage is 2.1 V(observable by the naked eye);the radiated optical power is 68.52 mW,energy efficiency is 4.3%,the current density is 51.6 A/cm-2,the brightness of the device is 106 cd/m2 under the driving voltage of 3.0 V;the maximum lumen efficiency is 50.35 lm/W under the voltage of 2.3 V and current density of 3.4 A/cm2.These results provide an important experimental basis for the design of LED microdisplays.5.Comparison between the light emitting angles of the standard LED chip for lighting and Micro Pixel LED chip of LED microdisplay for projection.The light emitting angle of the LED chip for lighting LED is 180° that means its distribution is Lambertian-like.The light display angle of the micro display LED projection chip is 80°,and its light distribution is collimated-type that fit Gaussian distribution after curve fitting.6.The influence of the size of Micro Pixel LED devices on the electrical characteristics is studied. |
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