Patent ID: 6832825
Filing Date: 2004-12-21
Classification: B41J

Abstract:
A printing apparatus for performing a printing operation with a print head having a plurality of print elements, comprising:an optical sensor having a light emitting portion and a light receiving portion; pattern forming means for printing on a print medium a plurality of predetermined patterns conforming to a light emitting wavelength range of said optical sensor, each of the plurality of patterns being formed by each corresponding print element or each corresponding block made up of a plurality of print elements; measuring means for emitting light from the light emitting portion of said optical sensor against the patterns printed on the print medium by said pattern forming means and measuring optical characteristics of the plurality of patterns; and correction means for taking, as a reference density, a predetermined density obtained from the optical characteristics of each of the plurality of patterns, and calculating a ratio of a density of the patterns to the reference density to perform a correction process based upon the calculated ratio.