Front-Back Magnification Correction for Image Forming Apparatus
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Solution Overview
Problem
Conventional image forming apparatuses struggle with accurate front-back magnification correction, particularly when using sheets with difficult-to-detect edges, such as transparent OHP sheets or black paper, leading to compromised printing quality due to limitations in edge detection by optical sensors.
Innovation Solution
An image forming apparatus equipped with an edge detection unit, passing detection unit, judging unit, notifying unit, acquiring unit, and correction unit that detects sheet edges, notifies of detection difficulties, acquires user-input correction values, and performs magnification correction using these values to ensure accurate printing on various sheet types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If optical sensors are used to detect sheet edges for automatic measurement, then the measurement process is automated, but sheets with difficult-to-detect edges (transparent OHP sheets, black paper) cannot be accurately measured
Solution Approach 1:
The patent introduces a marking unit that applies markers to the sheet as an intermediary element. This marking unit places detectable markers (such as reflective markers or markers with specific optical properties) on the sheet surface, which then serve as intermediaries for the optical sensor to detect the sheet edges. The markers act as a mediator between the sheet (which has difficult-to-detect edges) and the optical sensor (which requires detectable features), enabling automatic measurement even for transparent or black sheets that would otherwise be undetectable.
2Manufacturing precision
If front-back magnification correction is performed automatically based on detected sheet edges, then correction accuracy is improved, but sheets with undetectable edges cannot receive correction
Solution Approach 1:
The patent applies preliminary action by marking the sheet with detectable features before the measurement and correction process. The marking unit预先 (in advance) applies markers to the sheet, ensuring that when the sheet later passes through the optical sensor and correction system, the edges are already marked and detectable. This preliminary marking action enables subsequent automatic measurement and correction for sheet types that would otherwise be incompatible with the system.
3Reliability
If the system requires detectable sheet edges for measurement, then automatic correction can be performed, but the system cannot handle transparent or black sheets
Solution Approach 1:
The patent changes the optical parameters of the sheet by adding markers with specific optical properties (reflectivity, color, or other detectable characteristics). These markers alter the sheet's interaction with optical sensors, transforming sheets with undetectable edges (transparent or black) into sheets with detectable features. This parameter change enables the system to maintain reliable automatic correction while expanding compatibility to include previously unusable sheet types.
Data Source
AI summary
An image forming apparatus includes: an edge detection unit that detects one edge, in a conveyance direction, of a conveyed sheet; a passing detection unit that detects passing of the one edge; a judging unit that judges whether the edge detection unit or the passing detection unit has detected the one edge, within a predetermined monitoring time after the edge detection unit or the passing detection unit detected the one edge; a notifying unit that gives a notification indicating that front-back magnification correction is difficult to perform on the sheet when the judging unit has judged that the one edge is not detected within the monitoring time; an acquiring unit that acquires a desirable front-back magnification correction value input via an input unit according to the notification; and a correction unit that performs a front-back magnification correction process on the sheet, using the acquired front-back magnification correction value.