Inkjet Printhead Detection Using In-Document Reference Patterns
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Solution Overview
Problem
Existing imaging devices face challenges in accurately identifying and compensating for weak or missing inkjets during the printing process, which affects image quality due to errors in alignment and calibration of optical sensors and media distortions.
Innovation Solution
A method and system that detect inoperable inkjets by analyzing image data from a print job, identify offsets for their positions, adjust their positions, and compensate for them to maintain image quality, using an optical sensor and controller to operate the printheads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference patterns are printed separately to detect weak or missing inkjets, then inkjet identification can be performed, but productive printing resources are consumed and printing time is increased
Solution Approach 1:
The patent combines the detection function with the productive printing process by incorporating detection patterns within the print job itself rather than printing separate reference patterns. This merging allows the same printing operation to serve both productive and diagnostic purposes simultaneously.
Solution Approach 2:
The print job is designed to serve multiple functions: it produces the desired output document while simultaneously containing detection patterns that enable weak and missing inkjet identification. This multi-functionality eliminates the need for separate detection operations.
2Measurement precision
If optical sensors are used to detect reference patterns, then inkjet positions can be identified, but alignment errors and media distortions reduce detection accuracy
Solution Approach 1:
The system uses the detected positions of detection patterns to calculate offsets that reflect actual printing conditions including media distortion and alignment variations. These offset calculations provide feedback that compensates for distortions and improves subsequent inkjet position identification accuracy.
Solution Approach 2:
The patent dynamically adjusts position parameters by calculating offsets based on detected pattern positions. These parameter changes compensate for media distortion and alignment errors, allowing accurate inkjet identification despite varying printing conditions.
3Measurement precision
If hundreds or thousands of inkjets are monitored, then comprehensive coverage is achieved, but identification of single inoperable inkjets becomes challenging
Solution Approach 1:
The detection system divides the large array of inkjets into manageable groups by associating detection patterns with specific inkjet positions. This segmentation allows the system to process and analyze inkjet performance in organized units rather than as a single large dataset.
Solution Approach 2:
Detection patterns serve as intermediaries between the inkjets and the optical sensor system. These patterns provide detectable references that mediate the measurement process, enabling precise identification of individual inkjet positions and performance even within large arrays.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the accuracy of identifying and compensating for weak or missing inkjets, enhancing the quality of printed images by reducing errors caused by inoperable inkjets and media distortions.
Implementation Method 1
an optical sensor is used to generate image data of the reference pattern on an image receiving member
Data Source
AI summary
A method enables the positions of inoperable inkjets in printheads to be corrected for positional changes arising from shifts in media, shrinkage of the media, thermal expansion of optical sensors that detect the inoperable inkjets, and other measurement errors. The measurement errors are detected with reference to image data corresponding to a reference pattern printed within a portion of a print job. Thus, reference marks do not need to be printed in areas outside of a print job as previously required.