LCDs are a familiar name to everyone household as they offer some real advantages over other display technologies. They are thinner, lighter and draw less power in comparison to cathode ray tubes.
Passive and Active Matrix
Passive matrix LCDs utilizes a grid to supply the charge to a specific pixel on the display. The grid comprises of two glass layers called substrates. A substrate is given column while the other one is given rows built from a transparent conductive material known as indium-tin-oxide. Both the substrates are attached to integrated circuits that control when a charge is sent down a specific column or row.
The liquid crystal material is inserted in between the two glass substrates, and a polarizing film is added to the external side of every substrate. To start a pixel, the integrated circuit sends a charge down the proper column of one substrate and a ground activated on the exact row of the other. When the row and column intersect at the selected pixel, it results in the delivery of desired voltage to untwist the liquid crystal at that pixel.
Active matrix LCDs rely on thin film transistors (TFT) that are mainly tiny switching transistors and capacitors arranged in a matrix on a glass substrate. To deal with a specific pixel, the appropriate row is turn on and a charge is sent down to proper column. Since only the capacitor at the chosen pixel receives a charge it can hold the charge until the subsequent refresh cycle.
Color LCD
LCD that displays color should posses’ three sub-pixels with red, green and blue color filters to create each color pixel. With judicious control and difference of the voltage applied, the strength of each sub-pixel can range more than 256 shades. An amalgamation of sub-pixels generates an approximate palette of 16.8 million colors.
With persistently developing technology LCD utilizes numerous variants of liquid crystal technology that includes super twisted nematics (STN), dual scan twisted nematics (DSTN), ferroelectric liquid crystal (FLC) and surface stabilized ferroelectric liquid crystal (SSFLC).
