Method and apparatus for automatic measurement of various qualities of printed sheets
View Patent ↗Embodiments of the invention relate to the automatic measuring of such qualities of a printed sheet as reflectance excluding specular reflectance, reflectance including specular reflectance, e.g. gloss, transmittance, half-tone coverage, and the like.
1. A computer implemented method for automatic measurement of reflectance, comprising:
with at least one spectral sensor of a printer, measuring spectral reflectance at a plurality of angles relative to a sheet for each of a plurality of colored patches on said sheet, the colored patches being formed by the printer to enable real time enhancement of a printing process of the printer;
processing said measurements by a single angle per measurement independently of each other measurement; and
successively positioning an optical commutator to successively select an optical receiver from among a plurality of optical receivers, wherein each optical receiver is positioned at a different angle relative to illumination light rays projected from a light source, said optical commutator directing signals from said selected optical receiver to said spectral sensor for measurement of spectral reflectance.
2. The method of claim 1 , wherein measurement of each patch is performed by moving any of said sheet, said sensor, or both in other than X, Y coordinates.
3. The method of claim 1 , further comprising:
measuring a next angle of said plurality of angles after a full measurement of said sheet is made for a prior angle of said plurality of angles.
4. The method of claim 1 , further comprising:
measuring spectral reflectance for five angles relative to said sheet.
5. An apparatus for automatic measurement of reflectance, comprising:
at least one spectral sensor of a printer for measuring spectral reflectance at a plurality of angles relative to a sheet for each of a plurality of colored patches on said sheet, the colored patches being formed by the printer to enable real time enhancement of a printing process of the printer;
a processor for processing said measurements by a single angle per measurement independently of each other measurement; and
an optical commutator for successively positioning the optical commutator to successively select an optical receiver from among a plurality of optical receivers, wherein each optical receiver is positioned at a different angle relative to illuminating light rays projected from a light source, said optical commutator directing signals from said selected optical receiver to said spectral sensor for measurement of spectral reflectance.
6. The apparatus of claim 5 , further comprising:
a mechanism for performing measurement of each patch by moving any of said sheet, said sensor, or both in other than X, Y coordinates.