The diagram above shows a recent patent submitted by Canon in an attempt to improve image quality around the edges of images. They're hoping to reduce coloration and vignetting problems.
It's all about the micro lenses on the sensors. This new design is supposed to help direct and shift straight angled light using convex and curved surfaces. The intention is to catch and process as much light information as possible to give us, the users, a better image (especially on the edges). If you're a technical person and enjoy the details you can check out the full patent application HERE
via DP Review