Inkjet Head Nozzle Malfunction Detection via Segmented Test Patterns
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Solution Overview
Problem
Current inkjet image forming apparatuses face long suspension times in print jobs due to the need to individually determine ejection malfunction nozzles, which requires time-consuming image processing for test patterns printed during active printing.
Innovation Solution
The apparatus includes a recording head, a control unit, an ejection malfunction detecting unit, and a nozzle determining unit that prints and scans test patterns to identify and correct ejection malfunctions without suspending the print job unless defects are detected, using a first test pattern to detect density defects and a second test pattern to determine and correct malfunctioning nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the apparatus individually determines each ejection malfunction nozzle using image processing for scanned test patterns, then the precision of nozzle malfunction detection is improved, but the suspension time of the print job increases
Solution Approach 1:
The system performs preliminary detection using a first test pattern to identify density defects before committing to the time-consuming individual nozzle determination process. This preliminary action filters out cases where individual determination is unnecessary, thus reducing overall suspension time while maintaining detection precision when needed.
Solution Approach 2:
The detection process is segmented into two stages: (1) a quick preliminary detection stage using a first test pattern to identify potential density defects, and (2) a detailed individual nozzle determination stage using a second test pattern only when defects are detected. This segmentation allows the system to minimize time loss while preserving measurement precision for actual malfunction cases.
2Reliability
If the apparatus continuously performs test pattern printing and scanning to detect ejection malfunctions, then the reliability of print quality is improved, but the productivity of the print job decreases
Solution Approach 1:
Instead of continuous testing, the system employs periodic testing at strategic points during the print job (beginning, middle, and end). This periodic approach maintains print quality reliability through regular checks while preserving productivity by minimizing interruptions to the main printing process.
Solution Approach 2:
The system performs partial testing rather than exhaustive continuous testing. It uses a simplified first test pattern for quick checks and only performs the more comprehensive second test pattern when necessary. This partial action approach maintains sufficient reliability while maximizing productivity by avoiding excessive testing.
3Manufacturing precision
If the apparatus performs detailed image processing for scanned test patterns to determine ejection malfunction nozzles, then the manufacturing precision of defect detection is improved, but the device complexity increases
Solution Approach 1:
The image processing is segmented into two distinct levels: a simple density defect detection process using the first test pattern, and a more complex individual nozzle determination process using the second test pattern. This segmentation allows the system to achieve high manufacturing precision when needed while keeping the average device complexity manageable by using the simpler process most of the time.
Solution Approach 2:
The system performs preliminary defect detection using a simplified image processing approach with the first test pattern before engaging in complex individual nozzle determination. This preliminary action reduces the need for complex processing in most cases, thereby managing device complexity while maintaining the capability for high-precision detection when actual malfunctions are present.
Data Source
AI summary
An image forming apparatus includes a recording head, a control unit, an ejection malfunction detecting unit, and an ejection malfunction nozzle determining unit. The recording head ejects ink corresponding to an image to be printed, using arranged nozzles. The control unit determines nozzles corresponding to the image and causes the recording head to eject ink from the nozzles. The ejection malfunction detecting unit (a) prints a first test pattern on a print sheet using the recording head, and (b) detects a density defect due to ejection malfunction in a scanned image of the first test pattern. The ejection malfunction nozzle determining unit (a) prints a second test pattern using the recording head if the density defect is detected by the ejection malfunction detecting unit, and (b) does not perform printing of the second test pattern if no density defects are detected by the ejection malfunction detecting unit.