Utility knife that protrudes a blade from a stored stack of blades

A utility knife that protrudes a blade from a stored stack of blades comprising:

• a housing having an internal chamber;
• a blade track mounted within said internal chamber;
• a blade-carrier mounted within said blade track, said blade carrier being movable in a linear direction between an extended position and a retracted position, said blade carrier adapted to retain a single blade with this blade to protrude from said housing when said blade carrier is in said extended position;
• a thumb button connected to said blade carrier, said thumb button having an outer portion that is located exteriorly of said housing, said thumb button to be slidingly movable to cause said blade carrier to move between said retracted position and said extended position;
• an engaging block mounted on said blade carrier, said engaging block being movable between an engaging position and a non-engaging position, with said engaging block in said engaging position the single blade is engaged by said engaging block and is movable along with said blade carrier between said extended position and said retracted position;
• a pair of mounting pins mounted on said blade carrier, said engaging block being movably mounted on said mounting pins, said engaging block being biased by a single spring toward said engaging position;
• and
• a release button mounted on said housing, pressing of said release button when said blade carrier is in said extended position will cause said engaging block to be moved against said spring to said non-engaging position which will then permit extraction of said single blade from said housing.