Inkjet Nozzle Array Defect Detection via Shifted Test Patterns
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Solution Overview
Problem
Conventional methods for detecting defective ink discharge in ink jet recording apparatuses, especially at the ends of nozzle arrays, are inefficient, often leading to undetected issues due to the nature of test image patterns and the limitations of optical sensors with fewer effective elements.
Innovation Solution
A recording apparatus that includes a scanning unit, a recording control unit, and a detecting pattern to identify defective discharge by analyzing the number of nozzles affected, adjusting the recording position based on threshold values, and using a combination of patterns to ensure accurate detection of omissions at the center of the nozzle array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a test image is recorded using conventional methods, then the recording process is simple, but defective discharge at the ends of the nozzle array cannot be detected
Solution Approach 1:
The test image is divided into multiple regions including a first test region and a second test region. The first test region is used for normal recording position adjustment, while the second test region specifically tests the ends of the nozzle array by recording at a shifted position. This segmentation allows the system to maintain simple overall operation while adding specific detection capability for end-nozzle defects.
Solution Approach 2:
The system performs preliminary recording of the test image at a first recording position, then shifts the recording position to a second position to record the second test region. This preliminary action at different positions allows defective discharge at the ends of the nozzle array to be detected before normal recording operations begin.
2Device complexity
If optical sensor with small number of effective elements is used, then the device complexity is reduced, but position information of test image cannot be acquired
Solution Approach 1:
The patent introduces a recording medium as an intermediary between the optical sensor and the test image. The test image is first recorded on the recording medium, then the optical sensor reads the recorded image to detect position information. This intermediary approach allows the optical sensor to acquire position information without requiring a large number of effective elements, as the recording medium provides the necessary spatial reference.
3Reliability
If defective discharge occurs at the ends of the nozzle array, then the recording omission is not visible, but user cannot detect the defect
Solution Approach 1:
The patent creates an asymmetric testing arrangement where the second test region is recorded at a shifted position relative to the first test region. This asymmetric positioning causes recording omissions at the ends of the nozzle array to appear as visible gaps or distortions in the second test region, making them detectable to users while maintaining normal appearance in the first test region.
Data Source
AI summary
A recording apparatus to record an image to a recording medium includes a recording head having nozzles arranged in a predetermined direction in a nozzle array, scanning, recording control, obtaining, determining, and adjusting units. The scanning unit scans the recording head to the recording medium in a crossing direction. The recording control unit causes the recording head to record an adjusting pattern and a detecting pattern by discharging ink from a nozzle group. The obtaining unit obtains an information regarding number of defective discharge nozzles in the nozzle group based on the detecting pattern. The determining unit determines an adjusting value based on the recorded adjusting pattern where the indicated number is smaller than a threshold value, and not based on the adjusting pattern where the indicated number is larger than the threshold value. The adjusting unit adjusts the recording head recording position based on the determined adjusting value.