Image Forming Apparatus Cockling Detection via Moisture Differential
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Solution Overview
Problem
Existing methods for detecting sheet deformation in ink-jet printing, such as cockling, face challenges in distinguishing density unevenness caused by ink ejection variations from actual cockling, leading to potential erroneous determinations.
Innovation Solution
The proposed image forming apparatus includes a reading unit that reads a sheet with a chart image containing specific print patterns using different color inks, and a detection unit that detects sheet deformation by comparing moisture levels between printed and non-printed areas, thereby accurately determining cockling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a density sensor is used to detect cockling by measuring light reception changes, then sheet deformation can be detected, but density unevenness caused by ink ejection variations cannot be distinguished from actual cockling, leading to erroneous determinations
Solution Approach 1:
The sheet surface is divided into multiple measurement regions (first through fourth regions) with different ink application patterns. By segmenting the measurement areas and comparing results across regions, the system can distinguish between density variations caused by ink ejection and actual sheet deformation, thereby improving detection reliability while maintaining measurement precision
Solution Approach 2:
Different regions of the sheet are assigned different ink densities and patterns (some regions with ink, some without, varying concentrations). This local quality variation allows the detection system to compare measurements across different conditions and identify true cockling from artifacts, resolving the contradiction between detection accuracy and reliability
2Measurement precision
If multiple color inks with different densities are used in the chart image, then moisture amount differences between printed and non-printed areas can be detected, but the device complexity increases
Solution Approach 1:
The printing system uses standard multi-color inkjet printing technology that already exists in conventional printers. The same printing apparatus that prints normal documents is used to create the chart image with multiple color inks, eliminating the need for specialized equipment and avoiding increased device complexity while still achieving high moisture detection precision
Solution Approach 2:
The system uses the printer's own existing capabilities to generate the test chart and perform the measurements. The printer prints the chart image using its standard ink system, and the same device reads the printed material to detect moisture, making the system self-sufficient without requiring additional external equipment
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 enables high-accuracy determination of sheet deformation due to cockling, reducing the likelihood of erroneous interpretations and improving the quality of printed materials.
Implementation Method 1
a reading unit that reads a sheet on which a chart image is printed
Implementation Method 2
a detection unit that detects deformation of the sheet in an area of the sheet based on a difference between a moisture amount in a portion corresponding to an area in which the chart image in the read image obtained by the reading unit is printed and a moisture amount in a portion corresponding to a non-printing area
Data Source
AI summary
By an image forming apparatus comprising a reading unit configured to read a sheet on which a chart image is printed, the chart image including a first print pattern using a first color ink and a second print pattern using a second color ink whose color is different from the first color, containing at least part of the first print pattern, and having a predetermined density and a detection unit configured to detect deformation of the sheet in an area of the sheet based on a difference between a moisture amount in a portion corresponding to an area in which the chart image in the read image obtained by the reading unit is printed and a moisture amount in a portion corresponding to a non-printing area, determination of cockling is performed with a high accuracy.