Why does a computer screen go black?

Why does my (pc) computer screen go black when I lower the lid halfway as to adjust it?

• Whenever I try to adjust the top lid to see the screen better the screen goes black. Why is this? And my computer is about two years old. Sony pc windows 7

• Answer:

  I'm thinking that your computer is a laptop because you refer to "lowering the lid." Most laptop screens turn off when the lid is being lowered because the mechanism believes that the "lid" is about to be closed. Instead of having to manually do this, your laptop does this automatically to reserve battery and to prevent your screen from being on all night as it lights up the keyboard. In your case, when you lower it and then open it back up, you most likely notice that the screen goes off and then comes back on. This is because you lowered it enough to cause the screen to "believe" it is about to close. To prevent this from happening, you will have to stop lowering the screen as if you are going to close the laptop. Most laptops don't turn off the screen until the it is almost closed. Depending on your laptop and what it's been through it could be starting the process too early because of some kind of failure. But, I'm not there and I can't see what it is doing; so, to say it's experiencing a "failure" is jumping to conclusions. Mess around with it and see if what is doing is what I described. Hope this helps.