Patent ID: 8413337

Claim:
A utility knife, comprising: a handle having a front end; a first blade holder assembly constructed and arranged to releasably hold a first replaceable cutting blade at a position of use wherein the first replaceable cutting blade projects outwardly from a first opening at the front end of the handle, and to retract the first replaceable cutting blade into the handle; a second blade holder assembly constructed and arranged to releasably hold a second replaceable cutting blade at a position of use wherein the second replaceable cutting blade projects outwardly from a second opening at the front end of the handle, and to retract the second replaceable cutting blade into the handle, wherein the first cutting blade and the second cutting blade each have a forward terminal end; and an interlock assembly comprising a blocker structure positioned within the handle and between the first blade assembly and the second blade assembly and constructed and arrange to allow only one of the first replaceable cutting blade or the second replaceable cutting blade at a time to project outwardly from the front end of the handle, wherein the first replaceable cutting blade comprises a first linear edge, a first cutting edge opposite the first linear edge and a first mounting notch formed in the first linear edge, and the second replaceable cutting blade comprises a second linear edge, a second cutting edge opposite the second linear edge and a second mounting notch formed in the second linear edge, wherein the first blade holder has a first blade engaging protrusion and the second blade holder has a second blade engaging protrusion, wherein the first blade engaging protrusion engages within the first mounting notch to retain the first replaceable cutting blade in a fixed longitudinal position relative to the first blade holder and the second blade engaging protrusion engages within the second mounting notch to retain the second replaceable cutting blade in a fixed longitudinal position relative to the second blade holder, wherein a surface of the first or second blade holder assembly deflects the blocker structure into locking engagement with the other of the first or second blade holder assembly when the first or second blade holder assembly is moved from a retracted position within the handle to a position of use, to prevent the first blade and the second blade from being projected out the front end of the handle simultaneously, and wherein the first replaceable cutting blade and the second replaceable cutting blade are constructed and arranged to be aligned with their respective openings when the first replaceable cutting blade and the second replaceable cutting blade are positioned within the handle, and wherein the forward terminal ends of the first cutting blade and of the second cutting blade are offset from a central axis of the handle when projecting outwardly from the front end of the handle.