Inkjet Nozzle Detection via Offset Test Patterns
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Solution Overview
Problem
Existing inkjet image forming apparatuses require large storage capacity to store data for multiple ejection malfunction nozzles, which becomes inefficient when many nozzles are malfunctioning.
Innovation Solution
The apparatus includes a recording head, a control unit, and an ejection malfunction nozzle detecting unit that prints line-shaped or band-shaped test patterns with predetermined offset positions to detect and store only the offset position of periodical ejection malfunction nozzles, reducing storage needs by not storing individual nozzle positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual nozzle positions of ejection malfunction nozzles are stored, then accurate correction can be performed, but storage capacity requirement increases when many nozzles are malfunctioning
Solution Approach 1:
The patent segments the storage of nozzle position data by separating the regular interval pattern from the actual nozzle positions. Instead of storing all individual nozzle positions, the system stores only the regular interval value and uses it to generate individual positions mathematically, reducing storage requirements while maintaining correction accuracy
Solution Approach 2:
The patent changes the storage parameter from individual nozzle positions to a regular interval value that characterizes the periodic pattern of ejection malfunction nozzles. This parameter transformation allows the system to represent multiple nozzle positions using a single value, significantly reducing storage capacity requirements
2Measurement precision
If multiple test patterns with different offset positions are printed, then periodical ejection malfunction nozzles can be detected, but printing time and process complexity increase
Solution Approach 1:
The patent applies periodic action by printing multiple test patterns with different offset positions at regular intervals. This periodic testing approach enables the detection of periodical ejection malfunction nozzles by comparing density distributions across patterns, achieving high detection accuracy while maintaining efficient printing time through systematic repetition
Solution Approach 2:
The patent performs preliminary action by printing test patterns with predetermined offset positions before actual image printing. This advance detection allows the system to identify periodical ejection malfunction nozzles and store correction data in advance, ensuring accurate correction during subsequent printing operations without adding time delays
Data Source
AI summary
An ejection malfunction nozzle detecting unit prints plural test patterns on a print sheet using a recording head, and detects ejection malfunction nozzles on the basis of scanned images of the plural test patterns. The plural test patterns are line-shaped or band-shaped images for which a correction process has been performed at plural nozzle positions with a predetermined period. The nozzle positions of the plural test patterns are specified with offset positions different from each other. Further, the ejection malfunction nozzle detecting unit (a) determines a test pattern that densities at periodical ejection malfunction positions have been corrected among the plural test patterns on the basis of density distributions of scanned image of the test patterns, and (b) stores as ejection malfunction nozzle data an offset position of the determined test pattern into a storage device.