Here is a simplified diagram depicting how a notebook display component works and how an image displays on the screen is shown below.
Video cable: The video cable transmits a video signal from the motherboard to the LCD screen.The connector 1 connects the video cable to the motherboard (or video card).The connection 2 connects the video cable to the LCD screen.In most situations, the video cable is also responsible for supplying the FL inverter board with the appropriate voltage.At point 3, the video wire is connected to the FL inverter board.
FL inverter board: This board is in charge of converting low voltage DC power (point 3) to high voltage AC power (point 4), which is required to turn on the backlight bulb.The LCD screen (backlight bulb) will not light up when the laptop is turned on if the FL inverter board is broken, but you should be able to view a very dim image on the screen.
CCFL (backlight bulb): When the backlight bulb lights up, you can see an images on the LCD screen. In most cases the backlight bulb is a part of the LCD screen and if it’s bad, the entire screen has to be replaced. By the way, some specialized repair shops can replace the backlight bulb itself.
Lid close switch: The lid close switch is a little button near the display hinges that closes the lid.Because the switch is magnetic, some newer models don’t have a button.When the LCD is closed, you can configure your laptop to go into hibernation or standby mode.Power management software is used to do this.When the display is closed and the lid closure switch is held down, several modes are activated.If your laptop’s LCD screen won’t turn on when you open the display component, make sure the lid closure switch isn’t jammed inside.