US Patent 7121009 Can opener

The can opener is a side-cutting opener with handle levers which pivot vertically towards and away from one another. A rotary cutter wheel is normally retracted to a position inside one of said handle levers, but is thrust outwardly to cut into the rim of the can when the handle levers are squeezed together. A drive wheel engages the rim and is rotated by means of a rotary drive handle to cut the top off the can. Spreading the handle levers apart causes the cutting wheel to retract at the end of the cutting operation to release the cut-off top of the can.