Method for judging image quality using human-readable defect-sensitive patterns
AssigneePhogenix Imaging, LLC
InventorWilliam E. Bland
Life of this patent
Estimating the term…
Abstract
A method for monitoring the condition of an inkjet printhead. A test image is printed by the printhead and a second reference printhead. The density of ink dots in the test image is selected so that each dot just contacts adjacent dots while avoiding significant overlap. A defective nozzle can produce misplaced or undersized dots, creating abnormal spacing between adjacent dots. At the selected ink dot density, the abnormal spacing is most perceptible to the eye.
Claims16
A method of evaluating the performance of an inkjet printhead, comprising:
- (a) establishing an algorithm based on at least one of a group of factors consisting of the age of the suspect printhead, the volume of ink printed by the suspect printhead, the time elapsed since an immediately preceding diagnostic print from the suspect printhead, and a physical evaluation of the printhead, to determine when the test image should be printed;
- (b) creating a test image comprising a matrix of adjacent dots;
- (c) selecting an ink dot density which causes each dot of the matrix to overlap at least one adjacent dot;
- (d) printing the test image with the printhead;
- (e) detecting the presence of spaces between adjacent dots;
- and
- (f) comparing the spaces with a standard.
A method of evaluating the performance of an inkjet printhead, comprising:
- (a) establishing an algorithm based on at least one of a group of factors consisting of the age of the suspect printhead, the volume of ink printed by the suspect printhead, the time elapsed since an immediately preceding diagnostic print from the suspect printhead, and a physical evaluation of the printhead, to determine when the test image should be printed;
- (b) creating a test image comprising a matrix of dots;
- (c) selecting an ink dot density with standard spacings between adjacent dots such that the standard spacings can include zero and non-zero spacings;
- and
- (d) comparing actual spacings between adjacent dots with the standard spacings.
A method of evaluating the performance of a suspect inkjet printhead, comprising:
- (a) establishing an algorithm based on at least one of a group of factors consisting of the age of the suspect printhead, the volume of ink printed by the suspect printhead, the time elapsed since an immediately preceding diagnostic print from the suspect printhead, and a physical evaluation of the printhead, to determine when the test image should be printed;
- (b) creating a test image comprising a matrix of dots;
- (c) selecting an ink dot density so that adjacent dots in the matrix are spaced apart only when one of the adjacent dots is defective;
- (d) printing the test image with the printhead;
- and
- (e) detecting the presence of spaces between dots.
A method for evaluating the condition of a suspect inkjet printhead, comprising:
- (a) establishing an algorithm based on at least one of a group of factors consisting of the age of the suspect printhead, the volume of ink printed by the suspect printhead, the time elapsed since an immediately preceding diagnostic print from the suspect printhead, and a physical evaluation of the printhead, to determine when the test image should be printed;
- (b) using the suspect printhead and a reference printhead to produce a test print having a test image with at least one region, each region having a uniform matrix of overlapping ink dots;
- (c) examining the test image for the presence of unintended spaces between ink dots;
- and
- (d) replacing the suspect printhead based on the results of the examining step.
Dependencies are inferred from the claim text.