Image quality matching in a mixed print engine assembly system

A method of matching the contrast of single-color images produced on first and second print engines, at least one of which is an inkjet print engine:

• providing the first and second print engines, each including a respective densitometer;
• measuring the transmission density of a known filter with the densitometer of the first print engine to provide a first output voltage;
• measuring the transmission density of the known filter with the densitometer of the second print engine to provide a second output voltage;
• comparing the first and second output voltages;
• based on the comparison, compensating the output voltage from the densitometer in the first print engine for the output voltage for the densitometer in the second print engine;
• sensing an optical density of at least two areas of a first image produced on the first print engine, wherein the at least two areas have an optical density difference of at least 0.7;
• sensing an optical density of at least two areas of a second image produced on the second inkjet print engine, the at least two areas of the second image having optical densities corresponding to the optical densities of the at least two areas of the first image;
• comparing the corresponding sensed optical densities of the first and second images and determining if they are substantially equal;
• and
• if there is a difference of greater than 0.03 varying a potential initially applied to a primary imaging member of the second print engine, such that the contrast is varied by varying a droplet size as a function of the density so that the optical densities differ by less than 0.03.

A method of matching the contrast of single-color images produced on separate print engines of a print engine assembly, the assembly including one or more inkjet print engines, the method comprising:

• providing the print engines, each including a respective densitometer;
• measuring the transmission density of a known filter with the densitometer of each print engine to provide a respective output voltage;
• comparing the respective output voltages;
• based on the comparison, compensating the output voltage from at least one of the densitometers for the output voltage for at least one other of the densitometers;
• sensing a post-exposure potential in at least two areas of a first image produced on a first print engine such that the at least two areas would have an optical density difference of at least 0.7 on the fused print;
• sensing a post-exposure potential in at least two areas of a second image produced on a second print engine, the at least two areas of the second image having optical densities corresponding to the optical densities of the at least two areas of the first image;
• comparing the optical densities of the first image area and the second image area and determining if they are sufficiently close so as to produce prints having substantially equal densities in the appropriate areas;
• and
• if the optical densities of one image area produced on the first print engine and of one image area produced on the second print engine differ by more than 0.03 varying one or more of an potential initially applied to a primary imaging member, a bias applied to a development station, and an exposure in the first print engine so as to match the optical densities of the prints produced by the second print engine to those produced by the first print engine so that they differ by less than 0.03.