US Patent 6932683 Knife sharper having cutting edge protective structure

A knife sharpener includes a housing having one or more access slots for receiving knife blades to be sharpened, one or more grinding wheels rotatably received in the housing and disposed close to the access slots of the housing for grinding and sharpening the cutting edges of the knife blades. The housing includes one or more openings formed in either or both of the end portions of the access slot of the housing and communicating with the access slot of the housing, and having a width greater than that of the end portions of the access slot of the housing, for receiving and preventing the cutting edge of the knife blade from being blunted by the housing after sharpened by the grinding wheel.