Color Patch Arrangement for Thermochromism Error Reduction
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Solution Overview
Problem
Colorimetric value variations due to thermochromism in color image forming apparatuses lead to measurement errors, particularly when high-accuracy colorimetry is required, as the colorimetric value of heated patches differs from those at room temperature, affecting the quality of output images.
Innovation Solution
An image forming apparatus with a switchback mechanism that reverses the conveyance direction of the printing material and a colorimetry unit to obtain color information from patches, where the patches are arranged such that the average variation in color information is minimized by positioning patches with larger variations on the leading edge and those with smaller variations on the rear edge, and approximating the variation with a linear function having a negative gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the printing material is cooled to reduce measurement error due to thermochromism, then measurement precision is improved, but productivity deteriorates because it takes a long time to perform one measurement operation
Solution Approach 1:
The patent segments the printing material into multiple regions (leading edge side and rear edge side) with different thermal characteristics. By measuring patches in both regions and combining the results, the system achieves accurate colorimetry without requiring complete cooling of the entire printing material, thus resolving the contradiction between measurement precision and productivity
Solution Approach 2:
The patent performs preliminary measurements on patches located in different thermal regions before the printing material fully cools. By strategically positioning measurement locations and timing measurements to capture both hot and cooled regions, the system obtains accurate colorimetric data without waiting for complete cooling, maintaining both precision and productivity
2Productivity
If colorimetry is performed on heated patches immediately after fixing, then productivity is improved by reducing waiting time, but measurement precision deteriorates due to thermochromism
Solution Approach 1:
The patent divides the printing material into segments with different thermal states (leading edge region that remains hotter and rear edge region that cools faster). By measuring patches in both segments and combining the measurements, the system achieves accurate colorimetry while maintaining high productivity through immediate measurement after fixing
Solution Approach 2:
The patent performs preliminary measurements on strategically positioned patches in different thermal regions immediately after fixing. This preliminary action captures colorimetric data from both hot and cooled regions, allowing accurate overall color assessment without waiting for complete cooling
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 reduces color measurement errors caused by thermochromism while maintaining usability, improving tonal accuracy and image quality by strategically arranging patches based on their temperature-dependent color variations.
Implementation Method 1
obtain pieces of color information of patches of a plurality of colors, formed on the printing material, from light reflected by the patches of the plurality of colors upon irradiating the patches of the plurality of colors with light
Implementation Method 2
a fixing unit configured to heat and fix a toner image transferred onto a printing material
Implementation Method 3
a switchback mechanism configured to reverse a conveyance direction of a printing material on which the toner image is fixed
Data Source
AI summary
An image forming apparatus uses the difference in time taken for each patch to reach a color sensor, which occurs upon reversing the conveyance direction of a printing material. Due to this difference in time, the temperature of the printing material in detection by the color sensor differs among the respective patches. The error of a colorimetric value due to thermochromism is reduced by placing a patch with a colorimetric value which has a low temperature dependence so as to be detected earlier, and a patch with a colorimetric value which has a high temperature dependence so as to be detected later.