Laptop screen

Your screen inverter is bad, or your backlight lamp. (The Backlight Lamp is a CCL. Cold Cathode Lamp. Resembles a very small, thin fluorescent bulb)

Info,
http://www.insidemylaptop.com/replace-screen-inverter-dell-latitude-d800-laptop/

How to replace an inverter in an Acer Aspire 4315? I can't find you the exact manual at the moment. HOWEVER, I can give you a link to manuals that are close to the Acer Aspire 4000 Series laptops.

I have found through the years, that many laptop makes and models, are very similar, when it comes to disassembly, of the entire laptop, or just the LCD screen. These manuals are for various models of Acer Aspire laptops,

http://www.notebook-manuals.com/manuals/ACER/Aspire
And,
http://repair4laptop.org/disassembly_acer.html

Look online for Screen Inverter and also Backlight Lamp, for your Acre Aspire. There are many places that sell them. (Average price for the lamp, ranges from $8.99 to $14.99, or so)

your screen is probally going up or your battery and or charger could be malfunctioning