Resolution differences in my drawing

I'm making a drawing ang I have some views with a good resolution and some other views with a bad resolution.

As you can see in the image, the view at the bottom has a very bad resolution - lines doesn't look continuous - , but the cut view above it has a good resolution. If it had to do with the graphic card it will affect all the drawing.

If I try to print the drawing the problem is still there 

Does anybody have any idea on why this can be happening and how to solve it?

Thank you.