Self-sharpening utility knife

A cutter apparatus comprising:

• a blade housing;
• a blade carrier;
• and a blade;
• the blade housing enabled for receiving the blade carrier in sliding engagement within the blade housing in a longitudinal direction, between a retracted blade position and an extended blade position;
• the blade carrier providing a means for holding the blade in a preferred attitude, a means for securing the blade in the preferred attitude, and a means for pushing the blade carrier between the retracted blade position and the extended blade position;
• the blade housing providing a means for biasing the blade carrier in an upward direction, a means for sharpening the blade, and a means for engaging the blade carrier at plural longitudinal positions between, and including, the retracted blade position and the extended blade position;
• the pushing means cooperable with the biasing means for, with a downward pressure on the pushing means, disengaging the blade carrier from the engaging means for extension and retraction of the blade without contact between the blade and the sharpening means and alternately, with further downward pressure on the pushing means, for disengaging the blade carrier from the engaging means for extension and retraction of the blade carrier and forcing contact between the blade and the sharpening means.