Inkjet Deviation Calculation Using Asymmetric Test Marks
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Solution Overview
Problem
Inkjet image forming apparatuses face challenges in maintaining consistent ink landing positions due to variations in conveyance roller diameter, attachment conditions, and medium type, leading to deviations and reduced image quality, despite adjustments made based on detected deviations.
Innovation Solution
An image forming apparatus with a recording head that forms a test pattern with specific marks, using multiple nozzles to discharge ink, and an imaging device to capture and analyze the pattern, calculates the actual deviation distance based on the positions and ratios of the marks, allowing for precise adjustment of conveyance parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amount of conveyance is corrected based on detected deviation, then the deviation of ink landing position is reduced, but image quality deteriorates due to voids or excessive ink overlay
Solution Approach 1:
The test pattern is divided into multiple marks (first marks and second mark) with specific geometric relationships. By segmenting the measurement into multiple reference points rather than a single deviation detection, the system can calculate more accurate conveyance amounts and compensate for both conveyance roller variations and carriage inclination effects.
Solution Approach 2:
A test pattern consisting of multiple marks is introduced as an intermediary element between the conveyance system and the measurement system. This test pattern serves as a mediator that captures the combined effects of conveyance roller variations and carriage inclination, allowing the system to calculate and compensate for both factors simultaneously through geometric analysis of the marked positions.
2Ease of operation
If a single deviation detection method is used, then the system is simple to operate, but it cannot compensate for carriage inclination differences between forward and backward movement
Solution Approach 1:
The test pattern uses asymmetric mark arrangements where the first marks are formed during forward carriage movement and the second mark is formed during backward movement. This asymmetric design allows the system to detect and compensate for the different inclination angles that occur during forward and backward carriage travel, which would be invisible to symmetric measurement methods.
Solution Approach 2:
The system performs preliminary measurement by forming a test pattern with multiple marks before actual image formation. This preliminary action captures the mechanical characteristics (conveyance roller variations and carriage inclination) in advance, allowing the system to calculate correction values that will be applied during subsequent image formation processes.
3Device complexity
If conveyance roller variations are not compensated, then the system operates without complex correction mechanisms, but ink landing position deviates in the sub-scanning direction
Solution Approach 1:
The system uses its own recording head to form the test pattern marks that will be used for measurement and correction. This self-service approach eliminates the need for separate measurement devices, reducing system complexity while maintaining the capability to detect and compensate for conveyance roller variations through the geometric relationships of the formed marks.
Data Source
AI summary
An image forming apparatus includes an image forming device; an imaging device; and at least one processor including a pattern forming unit to cause a recording head to form a pair of first marks, with first and second nozzles disposed at a first distance from each other in a direction of conveyance of a recording medium, while the recording head moves in a first direction and cause the recording head to form a second mark while the recording head moves in a second direction, a position detector to detect positions of the first and second marks in a captured image, a ratio calculator to calculate a ratio between a distance between the first marks in the captured image and a deviation of the second mark in the captured image, and distance calculator to calculate a distance of the deviation based on the first distance and the ratio.