光电显示技术第3章-2013浅析.ppt

Linear Polarized Light Light usually vibrates in all direction A linear polarized light limit the vibration to one direction It absorbs the component of light that vibrate in all other direction. LCD require light to vibrate in one direction About Liquid Crystal Liquid crystal molecules can move freely while maintaining their orientation. It align itself to a polyimide film to the inside of a panel glass. When the two glass panels are not aligned the liquid crystal twists accordingly. The liquid crystal will also align to electric field. Light Path The light passes through the polarizer. The voltage applied to the electrodes controls the liquid crystal orientation The liquid crystal orientation controls the rotation of the incoming polarized light. Color filters are used in color LCD, where each color sub-pixel is controlled individually Direct Address Display When the display include limited variable components such as Watches Calculators Simple electronics is used to control the components Passive Matrix Display Passive matrix display has Rows of electrodes on one piece of glass. Columns of electrodes on the opposing piece of glass. Complex electrical waveform control the voltage differential at the intersection of the electrodes. The intersection of the columns and rows are the pixels Passive Matrix Display-disadvantages- As more rows and columns are added the range of the allowed voltage is reduced. At high range adjacent channels interferes Range limit reduces contrast Limit the types of useful liquid crystal. It is usually limited to about 50 rows Twisted nematic (TN) Display work best with large voltage variation. It can not be used in Passive Matrix Display Active Matrix Display Allow very high resolution Each sub-pixel is individually controlled by an isolated thin-film transistor (TFT). It allows the electrical signal for each sub-pixel to avoid influencing adjacent elements. The TFT is patterned into the glass layer A display with 1024x768 resolu