Strange stripe pattern on my screen?

There is a weird patterend of colour vertical lines on my iPhone 4 screen.

A few hours ago, I opened a new app and my screen froze. It started showing a weird pattern of coloured stripes which changed a few times. I couldn't turn it off, so I let it run out of battery. When it did, the stripes were still there, with the 'low' battery sign in front of it. I couldn't reset it, it didn't connect to iTunes, and at first it didn't seem to charge either but after a few minutes af being left in the charger, it turned on.

Now overall it seems to work normally, only the coloured stripes are still there, and it's really irritating because it's over my entire screen an it's flickering. Restarting or hard resetting my phone doesn't work wither, when my phone turns back on the stripes will be back right away.

If you have any suggestions on how to fix this, please tell me!