Patent ID: 7040733
Filing Date: 2006-05-09
Classification: B41J

Abstract:
1. A system for printing, said system comprising: a first optical sensor that is moveable relative to a print medium; a printhead that is coupled to and moves in tandem with said first optical sensor; a second optical sensor that is coupled to and moves in tandem with both said first optical sensor and said printhead; and a print medium feed mechanism comprising a roller, wherein said first optical sensor senses information on said roller and said second optical sensor concurrently senses information on said print medium; wherein said roller has located thereon a plurality of marks, said marks occurring along the circumference of said roller and also along the length of said roller and visible to said first optical sensor within the range of movement of said first optical sensor as said print medium is fed through said feed mechanism past said roller, said marks separated by known distances measured in a first direction along said circumference and known distances measured in a second direction along said length, wherein said known distances measured in said first direction and in said second direction are used to determined a position of said printhead relative to said print medium.