Patent ID: 7886445

Claim:
A utility knife comprising: a body having a handle portion and a frontal opening for a blade and a receiving cavity opening through said body; a cartridge containing a plurality of blades insertable into said receiving cavity, said cartridge having a front and a rearward tab; a blade carrier manually operable for receiving a blade from said cartridge and moveable into an extended position to position said blade through said opening into a cutting position; front and rearward cartridge catches adapted to releaseably engage said tabs to secure said cartridge in said body; a side button mounted in said knife body, said side button operatively connected to said front cartridge catch to release said front catch from engagement with said cartridge when depressed; and a blocking element for each of said cartridge catches, said blocking elements being movable into position to prevent release of said cartridge catches from said tabs when said blade carrier is in its extended position.