OBSTRUCTED-FIELD-INDICIA-SENSING DEVICE

An apparatus for monitoring the phasing relationship of a moving web of material of the type having a repeating series of graphics patterns thereon which repeat at ordinarily constant distance repeat length intervals of web travel and which contain separate repeating indicia portions which define a repeating indicia set which are positioned in a repeating indicia path extending longitudinally of the web comprising: an indicia detection device for providing an indicia detection pulse signal; a web travel sensing device for providing a web movement signal; an indicia profiling device for processing the indicia pulse signal and the web monitoring signal for generating a unique indicia image for each of the repeating indicia in a selected repeat length portion of the web; an indicia image storage device for identifying and storing the indicia images from a first selected repeat length portion of the web; a register indicia designation device for initially designating one of the repeating indicia to be register indicia; a register indicia sensing device for providing a register indicia pulse signal having pulses which in normal operation corresponds to the detection of the selected register indicia; a register indicia verification device for verifying that the repeating indicia which is in synchronization with said register indicia pulse signal is the currently designated register indicia; and a register indicia correction device for designating the indicia that is in synchronization with said register indicia pulse signal as the register indicia and replacing the previously designated register indicia therewith when the indicia image of the current register indicia is not verified to be the indicia which is in synchronization with the register indicia pulse signal.