|It's not the inverter if the backlight is on (ie: you can see anything at all). It's most likely the LCD panel, with a possibility of bad cable.|
To get a better idea of which one it might be, think of how you use the laptop - if you put stuff on top of the laptop when the screen is closed, or squish it in a tight notebook bag or backpack with the AC adapter on top and all sorts of books, etc.then it's likely the screen.
If you open/close the screen lots (3-10 times a day), it might be the cable. See if opening/closing makes a difference with the line patterns. If not, it goes back to a problem with the screen and it needs to be replaced.