Patent ID: 7296518
Filing Date: 2007-11-20
Classification: B41F

Abstract:
1. A method of measuring printed ink concentration on an opaque substrate on-line comprising: (a) projecting a light over the ink printed on the substrate measuring light reflectance as a camera response R, G or B, wherein R is the camera response for a red sensor, G is the camera response for a green sensor and B is the camera response for a Blue sensor; (b) Substituting the camera response R, G or B for reflectance (ρ wherein B, b and B 0 are constants having values of about 1.0, 4.271 and 0.606, respectively; and (c) calculating printed ink concentration (c) based on the following formula: wherein (E) is as calculated in step (b), (ε) is the relative (relative to the scattering of the substrate) unit extinction coefficient, a predetermined measurement of the pre-printed ink per unit concentration per unit thickness and (t) is the thickness of the printed ink either predetermined prior to or measured after printing.