Method and apparatus for registering overlapping printed images

Apparatus for determining the extent of misregister of colors in a multicolor image having a register indicia area wherein the average reflectivity of said area is substantially directly related to misregister of said colors in said predetermined direction, comprising:

• means for illuminating said register indicia area;
• means for sensing the intensity of light reflected from said area and for providing a signal having a single value which is representative of the total amount of light reflected from a substantial portion of said area, said signal value thus indicating the average reflectivity in said register indicia area, and
• means responsive to said signal for determining the extent of misregister in said predetermined direction in accordance with said signal value,
• wherein said register indicia area has two overlapping images formed therein in different colors, wherein two additional areas are provided, each having a solid image formed therein in a corresponding one of said different colors whereby the reflectivity of each said additional area is indicative of the color density of the corresponding color, wherein said means for illuminating and means for sensing respectively illuminate said areas and sense intensity of reflected light from each said additional area, said sensing means providing signals indicative of the intensity of light reflected from each said additional area, and wherein said means for determining comprises means for averaging the values of signals provided by said sensing means for each additional area, and for utilizing the resulting average value to correct the value of said signal provided by said sensing means for said register indicia area, whereby said determining means determines the extent of misregister in accordance with the values of the signals indicative of the intensity of reflected electromagnetic energy from said register indicia area and said additional areas.

The method of determining misregistration between two overlapped printed images, said method comprising the steps of:

• printing a first registration indicator in a first area at a known position relative to a first of said overlapped printed images, said first registration indicator including a first plurality of substantially parallel straight lines of first predetermined width and transversely separated from one another by a first predetermined dimension comparable to said first predetermined width,
• printing a second registration indicator in a second area at a known position relative to a second of said two overlapped printed images, said second registration indicator including a second plurality of substantially parallel straight lines of second predetermined width and transversely separated from one another by a second predetermined dimension comparable to said second predetermined width, said second plurality of lines at least partially overlapping said first pluralitv of lines,
• detecting the extent of overlap of said first and second plurality of lines by determining the total amount of resultant printed or space area within a significant portion of the overlapping areas of said first and second areas, and
• utilizing said extent of overlap as a measure of misregistration of said two overlapping printed images,
• wherein said first registration indicator includes a third plurality of substantially parallel straight lines of predetermined width and transversely separated from one another by a third predetermined dimension, said second registration indicator including a fourth plurality of substantially parallel straight lines of predetermined width and transversely separated from one another by a fourth predetermined dimension, said fourth plurality of lines being substantially parallel to said third plurality of lines and at least partially overlapping said third plurality of lines, said fourth plurality of lines being transversely offset from said third plurality of lines by a predetermined dimension,
• and further including the additional step of detecting the extent of resultant space between said first and second overlapping registration lines and the resultant space between said third and fourth overlapping registration lines, and utilizing said extents as an indication of the direction of misregistration of said overlapping printed images.

A method of indicating misregister between two overlapped images, comprising the steps of:

• forming a first plurality of spaced lines in a first indicia area occupying a known position relative to one of said two overlapped images, said lines being spaced apart by an amount which is small relative to the lengths of said lines and being substantially straight and disposed substantiallv parallel to one another,
• forming a second plurality of spaced lines in a second indicia area occupying a known position relative to the other of said overlapped images, said second plurality of lines being spaced apart by an amount which is small relative to the lengths of said lines and being substantially straight and oriented substantially parallel to one another and to said first plurality of lines such that when said first and second areas overlap one another the extent to which said lines of said first and second areas overlap one another changes with displacement between said two indicia areas in a direction transverse to said lines, said known position relative to the other of said overlapped images being selected so that when said overlapping images are in register said first and second indicia areas overlap,
• illuminating the area of overlap of said first and second indicia areas,
• detecting light returned from at least a significant portion of said first area of overlap and providing a first signal in accordance therewith, said signal having a value indicative of the amount of light returned from the entire said portion and thus representing the extent of overlap of said lines of said first and second indicia areas, and
• utilizing said signal value as a measure of misregister of said overlapping images,
• further comprising the steps of forming a third plurality of lines, similar to said first plurality of lines, in a third indicia area relative to said one of said overlapping images, forming a fourth plurality of lines, similar to said second plurality of lines, in a fourth indicia area relative to said other of said overlapping images, said positions of said third and fourth indicia area relative to the respective said images being selected such that said third and fourth pluralities of lines overlap one another to a different extent than said first and second pluralities of lines, illuminating the area of overlap of said third and fourth indicia areas, and detecting light returned from at least a significant portion of said area of overlap of said third and fourth indicia areas and providing a second signal in accordance therewith, said signal having a value representative of the amount of light returned from the entire said portion, and wherein said step of utilizing comprises the steps of utilizing said first and second signal values to determined the extent of misregister of said overlapping images.