Drive Roller Diameter for Image Registration Accuracy
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Solution Overview
Problem
Existing conveyance devices in image forming apparatuses face challenges in accurately performing image corrections due to fluctuations in conveyance speed, leading to positional deviations between detection marks on the recording medium and their scanned images, which affects the precision of skew and positional deviation corrections.
Innovation Solution
The conveyance device includes a conveyance roller pair with a drive roller and a driven roller, where the drive roller's diameter is set such that detection marks are positioned away from the leading end of the recording medium by an integral multiple of its circumference, ensuring that the actual and scanned positions of the marks coincide, thereby stabilizing image corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the conveyance roller pair conveys the recording medium, then the recording medium is transported to the image reading position, but conveyance speed fluctuations cause positional deviations between detection marks and their scanned images
Solution Approach 1:
The patent changes the geometric parameter of the drive roller (diameter) to a specific value that satisfies a mathematical relation, where the distance from the leading end to the detection mark equals an integral multiple of the roller circumference. This parameter adjustment ensures that speed fluctuations occur at intervals that align with the detection mark positioning, causing positional deviations to cancel out and resulting in accurate position detection despite speed variations.
2Ease of manufacture
If the detection mark is positioned at a fixed distance from the leading end, then the mark placement is simple, but conveyance speed fluctuations cause the scanned mark position to deviate from the actual mark position
Solution Approach 1:
The patent modifies the positional parameter of the detection mark by setting its distance from the leading end to be an integral multiple of the drive roller circumference. This specific parameter setting allows the system to maintain simple mark placement while achieving high precision in image correction, as the mark position naturally compensates for conveyance speed fluctuations.
3Area of moving object
If the drive roller diameter is increased, then the roller can handle larger recording media, but the positional relation between detection marks and roller rotation becomes less precise
Solution Approach 1:
The patent establishes a mathematical relationship between the drive roller diameter and the detection mark position, where the mark distance from the leading end equals an integral multiple of the roller circumference. This parameter relationship ensures that regardless of the roller size, the positional accuracy is maintained because the mark positioning is synchronized with the roller rotation cycles.
Data Source
AI summary
A conveyance device includes a conveyance roller pair to convey a recording medium to an image reading position of an image reading unit. The conveyance roller pair includes a drive roller and a driven roller. The driven roller contacts the drive roller and rotates following the drive roller. The drive roller has a diameter satisfying a relation in which a detection mark on the recording medium is on a position away from a leading end of the recording medium by an integral multiple of a circumference of the drive roller in a conveyance direction of the recording medium.