Safety utility knife

Claim 1

A safety utility knife comprised of a separable elongated shaped two-piece handle adapted to positionally secure and retain therein a replaceable cutting blade having a cutting edge said two-piece handle also being further provided with a spare cutting blade storage recess therein, which is old, characterized by: (a). an elongated geometrically configured spiral spring activated retractable blade guard cutting edge rod member provided with an insertably assembled first compression-extension spiral spring to movably communicate compressive and extensive coaction therewith, said rod member in the extended position being adjacently, downwardly disposed with respect to and in the same general plane as said cutting edge, said rod member having an inner end within the handle with a shoulder adjacent said inner end, (b). a mechanically cooperative geometrically configured spiral spring activated blade guard cutting edge rod member release and lock trigger provided with an insertably assembled second compression-extension spiral spring to movably communicate compressive and extensive coaction therewith, and (c). a manually initiated mechanically cooperative alignment coaction between said elongated geometrically configured spiral spring activated retractable blade guard cutting edge rod member and said geometrically configured spiral spring activated blade guard cutting edge rod member release and lock trigger to enable retraction of said blade guard cutting edge rod member through an opening in said blade guard cutting edge rod member release and lock trigger into a longitudinally disposed axially aligned first spiral spring tubular opening within said handle against the coactive compressive force of said first spiral spring retained therein to thereby expose the cutting edge of said cutting blade for severing service upon a manually imparted finger-force depression of said blade guard cutting edge rod member release and lock trigger against the coactive compressive force of said second spiral spring when said knife is employed in combination with a concurrent manually imparted use application pressure directed by way of said handle towards a surface to be severed, wherein, following which, upon release of said manually imparted use application pressure to said handle, said manually initiated mechanically cooperative alignment coaction being coactively cooperative reversely thereby enables automatic extension of said blade guard cutting edge rod member outwardly of said longitudinally disposed axially aligned first spiral spring tubular opening through said opening in said blade guard cutting edge rod member release and lock trigger under the coactive extensive force of said first spiral spring to position said blade guard cutting edge rod member in protective cover of the cutting edge of said cutting blade, and upon a subsequent release of said manually imparted finger-force depression upon said blade guard cutting edge rod member release and lock trigger thereby also enables said blade guard cutting edge rod member release and lock trigger to automatically extend under the coactive extensive force of said second spiral spring and thereupon cause a positive mechanical engagement locking of said blade guard cutting edge rod member by means of said trigger opening engaging said shoulder on said rod member in a close proximity downwardly disposed longitudinally extended position relative to and guardably protective of said cutting edge of said cutting blade.