Abstract: Provided are a printing apparatus and a conveying-error controlling method capable of printing a high-quality image by correction reflecting the conveying amount of a printing medium. A provided inkjet printing apparatus prints images by printing scans for actual printing and by conveying the printing medium with a roller orthogonally to the printing-scan direction. In each printing scan, the printing medium is scanned with a print head having an array of nozzles from which the ink is ejected. The print head moving direction differs from the arranging direction of the nozzles in the array. The apparatus includes a conveying controller to control the conveying of the printing medium on the basis of a correction value used to correct a conveying error of the roller. The conveying controller changes the correction value to be applied in accordance with the conveying amount of the printing medium between two scans with the print head.

Abstract: Performed is conveying-error correction in accordance with the kind and the number of rollers that are actually involved in the conveying of a printing medium. Each of the rollers that are potentially involved in the conveying of the printing medium has a unique amount of eccentricity, and may affect the quality of image to be printed in a peculiar manner. To address this problem, a surface of the printing medium is divided into areas according to the number and the combination of the rollers that are actually involved in the conveying. A pattern each is printed for each of the areas thus formed while the pattern enables the detection of the conveying error. A correction value to correct the conveying error is calculated using each of the patterns. The correction values thus obtained are reflected in the conveying of the printing medium.

Abstract: The sequence of the acquisition of a correction value of a conveying error depending on the eccentricity of the conveying roller (correction value for eccentricity) and the acquisition of a correction value of a conveying error depending on the outer diameter of the roller (correction value for outer diameter) is considered to acquire a precise correction value for outer diameter. A test pattern to acquire the correction values for eccentricity and for outer diameter is formed with an area exceeds the area corresponding to an integer multiple of the circumferential length of the roller. The correction value for eccentricity and that for outer diameter are acquired in this sequence. The fluctuation in the conveying error is reduced by the application of the correction value for eccentricity, and the influence of the excess area is made smaller before the correction value for outer diameter is acquired by averaging the conveying errors.

Abstract: While a conveying error of a roller depends on the eccentricity of the roller, the amount and the state of the eccentricity sometimes makes the roller have different conveying errors from one point in the longitudinal direction of the roller to another. There is provided a construction for obtaining a correction value that is suitable for the correction of the conveying error even in such a case as described above. To this end, plural test patterns are formed in the longitudinal direction of the roller. Then, a suitable correction value for correcting the conveying error that depends on the eccentricity of the roller is obtained on the basis of these test patterns.

Abstract: An object of the present invention is to provide an ink jet printing method and ink jet printing apparatus capable of outputting a smooth monochrome photograph with indistinctive beading and conveying unevenness even in monochrome black mode for printing an image by using achromatic color inks. For this object, if it is determined that printing is carried out in the monochrome black mode, different mask patterns, such as mutually-exclusive mask patterns or mask patterns having a logical product result that shows a state where low-frequency components are less than high-frequency components, are set for two or more kinds of achromatic color inks. Use of such mask patterns suppresses the generation of grains of achromatic color inks, increases dispersibility of the grains, and also makes positions where conveying unevenness appear indistinctive.

Abstract: To provide a prepared color separation table for an inkjet printing apparatus that suppresses unevenness due to differences in the color of regular reflected light when a printing medium surface used for printing pigment-based inks is irradiated with light and which can output a high quality image. It is a printing apparatus that can carry out printing using recording materials and when reproducing a color of a predetermined color region using numerous types of the said recording materials with different regular reflected light colors it uses at least one type of the recording materials over the entire area in the predetermined color region.

Abstract: By suppressing deviation of dot-formation positions stemming from insufficient accuracy in conveying a printing medium due to eccentricity of a conveying roller, a printed image in which unevenness is less visible is obtained. An accumulated amount of conveyance errors is reduced by narrowing a nozzle-use range and by reducing a conveyance amount over an entire printing region according to the number of colors to be used and desired printing quality in printing an image. Moreover, the nozzles used when the nozzle-use range is narrowed are not fixed, and are switched to be used as appropriate. This prevents only certain nozzles from being used concentratedly, and allows all of the nozzles to maintain substantially the same ejection performance.

Abstract: By suppressing deviation of dot-formation positions stemming from insufficient accuracy in conveying a printing medium due to eccentricity of a conveying roller, a printed image in which unevenness is less visible is obtained. An accumulated amount of conveyance errors is decreased by narrowing a nozzle-use range and reducing a conveyance amount over an entire printing region according to a mode used for printing an image in which the coverage of a printing medium is low due to a small number of ink colors to be used, for example, a mode used for printing a monochrome image by using a black ink dominantly in all of the density regions.