This is quite an interesting idea from Canon. I mean, photographers are often losing lens caps, especially if they shoot on location. You take off your cap, put it down somewhere, come back to it after shooting and suddenly, oh, where’s it gone? I’ve lost track of how many I’ve lost by now, to the point where I usually buy 5 at a time.
Canon’s new patent application (JP 2019-113645), though, describes a lens cap with a barndoor style configuration that allows you to open it up, shoot through it, and then close it again without having to take it off the lens at all.