Patent ID: 7591906

Claim:
An apparatus for performing an operation on a substrate on which a structure is provided, which structure bounds a number of areas on the substrate, wherein the apparatus comprises: a table for placing the substrate thereon; an inkjet printhead for delivering liquid at a desired time in substantially each area; a displacement assembly for displacing the printhead relative to the substrate; at least one sensor for observing the structure provided on the substrate and for producing a signal correlated with the position of each area bounded by the structure, the position of the at least one sensor being fixed relative to the printhead; and a control for processing the signals produced by the at least one sensor, controlling the displacement of the displacement assembly and timing the delivery of liquid by the printhead on the basis of the signals produced by the at least one sensor, wherein the at least one sensor observes the structure and produces the signal simultaneously while the control (i) processes the signals produced by the at least one sensor, (ii) controls the displacement of the displacement assembly, and (iii) times the delivery of liquid during relative movement of the substrate with respect to the printhead during substantially a whole process time of delivering liquid into the respective areas on the substrate bounded by the structure.