Sheet Length Measuring Device Eccentricity Correction
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Solution Overview
Problem
Existing sheet length measuring devices in image forming apparatuses are complex and require multiple measurements to achieve high accuracy, especially when dealing with eccentricity or thermal expansion in rotating bodies.
Innovation Solution
A sheet length measuring device comprising a rotating body, a position detecting unit, a rotation amount measuring unit, and a calculating unit that calculates the corrected sheet length using pulse signals and rotation angles at the leading and trailing ends, allowing for accurate measurement even with eccentricity or thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurements are performed to achieve high measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-storing the relationship between rotation angles and sheet conveying amounts in a storage unit before actual measurement. This allows the system to quickly retrieve correction data during measurement without performing complex real-time calculations or multiple measurements, thereby achieving high accuracy while simplifying the measurement process.
Solution Approach 2:
The patent replaces complex mechanical measurement systems with an electronic data processing approach. Instead of using multiple physical sensors or repeated mechanical measurements, the system uses a rotation amount measuring unit to detect roller rotation and substitutes mechanical complexity with electronic storage and calculation of rotation angle versus conveying amount relationships.
2Measurement precision
If multiple measurements are performed to achieve high measurement accuracy, then measurement precision improves, but measurement time increases
Solution Approach 1:
The patent applies preliminary action by pre-storing the relationship between rotation angles and sheet conveying amounts in a storage unit before actual measurement. This allows the system to quickly retrieve correction data during measurement without performing complex real-time calculations or multiple measurements, thereby achieving high accuracy while simplifying the measurement process.
3Device complexity
If rotation amount measurement is performed without correcting for eccentricity and thermal expansion, then device complexity decreases, but measurement precision deteriorates
Solution Approach 1:
The patent applies self-service by using the rotating body's own rotation amount measurements to correct for its own eccentricity and thermal expansion errors. The rotation amount measuring unit detects the actual rotation, and the calculating unit uses this data to self-correct the sheet length measurement, eliminating the need for external correction mechanisms while maintaining high precision.
Solution Approach 2:
The patent implements feedback by continuously monitoring the rotation amount of the rotating body and using this information to correct measurement errors. The system measures the actual rotation, compares it with expected rotation, and applies corrections based on the detected deviations, thereby maintaining measurement accuracy despite eccentricity or thermal expansion.
Data Source
AI summary
A sheet length measuring device includes a rotating body configured to rotate with a movement of a sheet in a conveying direction; a position detecting unit configured to detect leading and trailing ends of the sheet passing through a position of the rotating body; a measuring unit configured to measure a rotation amount of the rotating body and output an origin signal per one revolution of the rotating body; a storage unit configured to store changes of a sheet conveying amount with respect to respective rotation angles in one revolution of the rotating body; and a calculating unit configured to calculate a corrected length of the sheet from a value obtained from a rotation angle of the rotating body when the leading end of the sheet is detected and a value obtained from a rotation angle of the rotating body when the trailing end of the sheet is detected.