Patent ID: 8010001

Claim:
A method of calculating a Fractional Area Coverage (FAC) for determining the solid developed mass per unit area (DMA) to evaluate the effectiveness of a xerographic printing process, the method comprising: (a) measuring a plurality of test patterns having varying predetermined toner or ink densities formed thereon using a sensing system, the sensing system comprising: an illuminator configured to emit a beam of light at a point on a target, thereby producing a generally specular reflectance at a specular angle and generally diffuse reflectance at a diffuse angle; a specular sensor configured to detect the generally specular reflectance at the specular angle; a diffuse sensor configured to detect the generally diffuse reflectance at the diffuse angle; and a processor configured to process the generally specular reflectance detected by the specular sensor and the generally diffuse reflectance detected by the diffuse sensor; (b) for each of the test patterns measured, calculating a measured FAC value (mFAC) from the specular and diffuse sensor readings for that test pattern; (c) calculating the true Fractional Area Coverage (FAC) for each measured test pattern as a function of alpha (α), representing a fraction of diffuse reflectance at the specular angle, wherein alpha is calculated as a function of: (i) a maximum mFAC value determined from the measurements of the test patterns (SpecFACmax); or (ii) a slope measured from the maximum mFAC value to the mFAC value corresponding to a highest DMA value in a sweep (SpecSLOPE).