Actually it looks like there's either too much/too little pressure put on the screen - it's not necessarily broken. Does the screen react in any way when you put pressure on it or on the patch?
It would also seem that your DS Lite was previously dismantled or it's a refurb from China - not that you'd have any way of knowing that since those units entered the market as "new", so the build quality may be questionable.
Press down on the bottom right and left-hand corners of the bottom part of the system - do they move in any way? If so, the system may have been put together wrongly or the screws were not tightened enough and got loose.
Additionally you could fiddle around with the screen adjustment screw which is situated directly beneath the battery - twist it bit by bit clock or counter clockwise and check if it affects the screen in any way.
If all this fails, you might have to carefuly open up the system following one of the online guides (videos can be found online) and have a look inside, check the ribbons etc. Worst case scenario, you'll need a new bottom screen.