Led And Lcd Displays

LIQUID CRYSTAL DISPLAYS

PRESENTED BY:SUSHANTA SARKAR 4TH YEAR ETC FX-042

LCD (LIQUID CRYSTAL DISPLAY) A liquid crystal is intermediate between a liquid and a solid. In a liquid, the molecules do not have long range order. The molecules are randomly oriented. In a liquid crystal, the molecules have long rod shapes. The molecules’ positions are random but their orientations can be aligned with one another in a regular pattern.

LCD (LIQUID CRYSTAL DISPLAY) If we put a liquid crystal material between two pieces of glass scored with horizontal and vertical lines, the liquid crystal molecules twist to try to align with the lines in the glass. These twisted molecules acts as wave guide for light. As the light passes through the liquid crystal layers, the molecules change the light's plane of vibration to match their own angle.

LCD (LIQUID CRYSTAL DISPLAY) If we apply an electric charge to liquid crystal molecules, they untwist! When they straighten out, they change the angle of the light passing through them.

LCD (LIQUID CRYSTAL DISPLAY) To construct an LCD pixel, we put the liquid crystal layer between two polarizers, we can control whether the pixel lights up or not. A polarizer allows only light with a particular electric field orientation to pass through it.

LCD (LIQUID CRYSTAL DISPLAY) E=0

E>0

LCD (LIQUID CRYSTAL DISPLAY) If we apply an electric charge to liquid crystal molecules, they untwist. When they straighten out, they change the angle of the light passing through them so that it no longer matches the angle of the top polarizing filter. Consequently, no light can pass through that area of the LCD, which makes that area darker than the surrounding areas.

LCD (LIQUID CRYSTAL DISPLAY) In a calculator to make a number you “turn on” the cells that you want to make. The LCD molecules untwist and prevent light from passing through the cell.

LCD (LIQUID CRYSTAL DISPLAY)

Applications of LCD