Test pattern for detecting an impaired nozzle with transverse offset

A method for detecting an impaired nozzle of a print head of an inkjet printing device;

• wherein the print head comprises K nozzles, with K>10, that are designed to print corresponding K dots in corresponding K columns of a line of a print image onto a recording medium;
• wherein the method comprises
• printing a test pattern by the print head onto the recording medium, the test pattern comprising a matrix with matrix points, wherein
• the matrix of matrix points has K columns for the corresponding K nozzles and N rows, with N>1;
• the test pattern has a respective sequence of N matrix points in each of the K columns, of which N matrix points one or more are printed matrix points and one or more are non-printed matrix points;
• a printed matrix point in a defined column and in a defined row indicates that the nozzle corresponding to the defined column prints a dot upon printing the defined row of the test pattern;
• a non-printed matrix point in the defined column and in the defined row indicates that the nozzle corresponding to the defined column does not print a dot upon printing the defined row of the test pattern;
• the test pattern is designed such that a respective first printed matrix point is arranged in the K columns of the test pattern, which first printed matrix point has at least one directly adjacent first printed matrix point within the same row, which at least one directly adjacent first printed matrix point is spaced apart from the first printed matrix point by precisely the first number L1 of columns, and L1≥2 or L1≥3;
• the test pattern is designed such that a respective first printed matrix point is arranged in K−k1 columns of the test pattern, which respective first printed matrix point has on both sides a respective directly adjacent first printed matrix point within the same row, which respective directly adjacent first printed matrix point is spaced apart from the first printed matrix point by precisely the first number L1 of columns;
• k1 depends on the first number L1 of columns;
• and
• k1=2*L1;
• the test pattern is designed such that a respective second printed matrix point is arranged in the K columns of the test pattern, which respective second printed matrix point has at least one directly adjacent second printed matrix point within the same row, which directly adjacent second printed matrix point is spaced apart from the second printed matrix point by precisely a second number L2 of columns;
• L2≥2;
• the first number L1 of columns and the second number L2 of columns are different;
• the test pattern is designed such that the respective second printed matrix point is arranged in K−k2 columns of the test pattern, which respective second printed matrix point has on both sides a respective directly adjacent second printed matrix point within the same row, which respective directly adjacent second printed matrix point is spaced apart from the second printed matrix point by precisely the second number L2 of columns;
• k2 depends on the second number L2 of columns;
• and
• k2=2*L2;
• recording sensor data with regard to the test pattern printed onto the recording medium;
• and
• detecting an impaired nozzle of the print head based on the sensor data.

An inkjet printing device, comprising:

• a print head comprising K nozzles, with K>10, the K nozzles designed to print corresponding K dots in corresponding K columns of a line of a print image onto a recording medium;
• a sensor unit configured to acquire sensor data with regard to a print image printed onto the recording medium;
• and
• a control unit comprising a processor configured to:
• instruct the print head to print a test pattern onto the recording medium, the test pattern comprising a matrix with matrix points, wherein
• the matrix of matrix points has K columns for the corresponding K nozzles and N rows, with N>1;
• the test pattern has a respective sequence of N matrix points in each of the K columns, of which N matrix points one or more are printed matrix points and one or more are non-printed matrix points;
• a printed matrix point in a defined column and in a defined row indicates that the nozzle corresponding to the defined column prints a dot upon printing the defined row of the test pattern;
• a non-printed matrix point in the defined column and in the defined row indicates that the nozzle corresponding to the defined column does not print a dot upon printing the defined row of the test pattern;
• the test pattern is designed such that a respective first printed matrix point is arranged in the K columns of the test pattern, which first printed matrix point has at least one directly adjacent first printed matrix point within the same row, which at least one directly adjacent first printed matrix point is spaced apart from the first printed matrix point by precisely the first number L1 of columns, and L1≥2 or L1≥3;
• the test pattern is designed such that a respective first printed matrix point is arranged in K−k1 columns of the test pattern, which respective first printed matrix point has on both sides a respective directly adjacent first printed matrix point within the same row, which respective directly adjacent first printed matrix point is spaced apart from the first printed matrix point by precisely the first number L1 of columns;
• k1 depends on the first number L1 of columns;
• and
• k1=2*L1;
• the test pattern is designed such that a respective second printed matrix point is arranged in the K columns of the test pattern, which respective second printed matrix point has at least one directly adjacent second printed matrix point within the same row, which directly adjacent second printed matrix point is spaced apart from the second printed matrix point by precisely a second number L2 of columns;
• L2≥2;
• the first number L1 of columns and the second number L2 of columns are different;
• the test pattern is designed such that the respective second printed matrix point is arranged in K−k2 columns of the test pattern, which respective second printed matrix point has on both sides a respective directly adjacent second printed matrix point within the same row, which respective directly adjacent second printed matrix point is spaced apart from the second printed matrix point by precisely the second number L2 of columns;
• k2 depends on the second number L2 of columns;
• and
• k2=2*L2;
• record the sensor data with regard to the test pattern printed onto the recording medium from the sensor unit;
• and
• detect an impaired nozzle of the print head based on the sensor data.