Abstract: Described are systems and methods for printing that use an optical sensor that is moveable relative to a print medium, and a mark that is visible to the optical sensor within the range of movement of the optical sensor. The mark provides a fixed and known location that can be used to establish a position of the optical sensor relative to the print medium.

Abstract: An interpolation circuit and method for interpolating first and second out-of-phase ramp signals are disclosed. The interpolation circuit generates fractional ramp signals from the ramp signals and utilizes four multiplexers and two comparators to compare selected ones of the ramp signals. The comparator outputs are used by a finite state machine to provide a next state for the interpolator from the current state and the comparator outputs. The signals selected by the multiplexers are determined by the current state generated by the finite state machine. The finite state machine also detects a startup condition and determines the correct current state from the comparator outputs when different ramp signals are applied to the comparators. The ramp signals can be generated from out-of-phase signals from an optical comparator. The interpolation circuit generates new out-of-phase signals having a larger number of states per cycle.