Patch Image Arrangement for Density Uniformity in Image Forming
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in mixed-color calibration, as they require a large number of patches to suppress uneven density in the sub-scanning direction, leading to increased recording media usage and inefficiency.
Innovation Solution
The apparatus generates a patch image with mixed-color patch sets where patches of the same tone are arranged at a distance close to (N+½) times the period of uneven density in the circumferential direction, and single-color patch sets are placed between these mixed-color patch sets, optimizing the arrangement to fit on a single page and effectively averaging uneven density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all patches are staggered by a distance corresponding to half the length of the period of uneven density in two positions in the sub-scanning direction, then the effect of uneven density is suppressed, but the number of patches increases resulting in increased recording media usage
Solution Approach 1:
The patent applies local quality by differentiating the staggering distance for single-color patches versus mixed-color patches. Single-color patches use a larger staggering distance (half the period of uneven density) to effectively suppress uneven density, while mixed-color patches use a smaller staggering distance ((N+0.5) times the period where N is a non-negative integer). This localized differentiation allows the system to maintain density uniformity where needed while reducing the total number of patches required.
Solution Approach 2:
The patent applies partial action by selectively applying the maximum staggering distance only to single-color patches rather than uniformly applying it to all patches. For mixed-color patches, which are less sensitive to uneven density effects, a reduced staggering distance is used. This partial application of the stringent staggering requirement reduces the overall number of patches needed while maintaining sufficient density uniformity for critical single-color regions.
2Quantity of substance
If patches are arranged to fit on a single page, then recording media usage is reduced, but uneven density suppression becomes insufficient
Solution Approach 1:
The patent ensures that single-color patches, which are most vulnerable to uneven density effects, are arranged with sufficient staggering distance to maintain uniformity, while mixed-color patches can be positioned more closely. This local quality differentiation allows the patch image to fit on fewer pages while maintaining density uniformity in the critical single-color regions.
Solution Approach 2:
The patent segments the patch image into distinct single-color patch sets and mixed-color patch sets, allowing different arrangement strategies for each segment. Single-color patches are spaced apart to suppress uneven density, while mixed-color patches are positioned to optimize space utilization. This segmentation enables the entire patch image to fit on a single page while maintaining sufficient density uniformity through the differentiated arrangement of its components.
3Reliability
If the distance between same tone patches is set to (N+½) times the period of uneven density, then uneven density is effectively averaged, but the arrangement complexity increases
Solution Approach 1:
The patent applies parameter changes by introducing the integer parameter N to generalize the staggering distance formula from a fixed value (0.5 times the period) to a variable value ((N+0.5) times the period). This parameterization allows flexible adjustment of the staggering distance to accommodate different patch configurations and page layouts while maintaining the core function of averaging uneven density. The integer N can be selected to optimize the balance between density uniformity and arrangement simplicity.
Data Source
AI summary
An image forming apparatus includes: a patch-image generating unit that generates a patch image for measuring a color reproduction characteristic and correcting color, the patch image including mixed-color patch sets each including a plurality of patches each formed by overlaying a plurality of color materials so that patches having the same color and the same tone value included in the mixed-color patch sets are arranged away from each other in a circumferential direction of a photosensitive element and a distance between same tone patches, which are two patches having the same color and the same tone value, is close to (N+½) times the length of a period of uneven density which periodically occurs in the circumferential direction of the photosensitive element (N is an integer equal to or greater than 0); and an image forming unit that forms the generated patch image on a recording medium.