HOW LCD DISPLAY WORKS?

How LCD Display Interface Circuit works?
An LCD -liquid crystal display is an electronically-modulated optical device made up of any number of pixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in color or monochrome.
They can be optimized for static text, detailed still images, or dynamic, fast-changing, video content.
Old type of LCD are monochrome types which only display one certain color while the modern types are colored ones that can display rich text and images.
LCD's resolution of display depends on the amount of pixels into it, the highest amount designed looks and displays best.

Now, LCd wont work without a light source and a reflector to drive it pixels to form an image information.
This typical block diagram below will help us a brief explanation oh how the LCD can produce an text and images on mobile phones handsets. 
The block diagram shows the LCD gets a data source from the application processor, so therefore LCD is being controlled by the application processor to produce a detail images,
LED is a light emitting diode that can produce light, this light source of an LED is the one that reflect at the back of an LCD, without this LED light reflection on the back of an LCD  it will result a black or dark screen displays.
LCD also needs a power supply voltage to activate its liquid crystal arrays inside of it, so that is why a voltage supply is also very important for that matter.

 An LCD Display Circuit Schematic diagram of a mobile phones below interprets how the whole circuitry of an LCD being connected and designed. A circuit start from an application processor that controls and sends data to LCD connector which where the LCD is being connected. Before the data reach to the LCd connector it is being filtered for Electromagnet Interference protection. The LED light circuit and a power supply voltage is also provided for it is also work an important part on LCD circuit.

The picture below interprets the schematic diagram above on how  each components layout are being mounted on a particular mobile phones printed circuit board.

Always keep in mind that LCD needs the following sources to make it work completely,
1. Data control signal from the application processor
2. LED light that reflects on it back so that display will reveal completely.
3. A power supply voltage to turn the LCD activated.

 A failure of these three sources will result on display problem issues.