Conveyance Device Skew Correction Multi-Feed Prevention
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Solution Overview
Problem
Existing printing apparatuses face issues with multi-feed of print media when the print medium size in the feed direction is small, due to insufficient control over conveyance force during skew correction.
Innovation Solution
A conveyance device with a feed unit, a first conveyance unit forming a nip portion between rollers, and a control unit that adjusts conveyance force based on print medium size to prevent multi-feed by applying additional force during skew correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional conveyance force is applied to correct skew by overfeeding the print medium, then skew correction is improved, but multi-feed occurs when print medium size is small
Solution Approach 1:
The patent applies dynamics by making the pick-up roller movable rather than fixed. The pick-up roller can move in the feed direction based on detection results, allowing it to adapt its position dynamically. This enables the system to apply additional conveyance force when needed for skew correction while avoiding unnecessary contact that would cause multi-feed, thus resolving the contradiction between precision and reliability.
Solution Approach 2:
The patent implements feedback by using a detection unit to monitor the print medium's position and characteristics, then feeding this information back to the control unit. The control unit adjusts the pick-up roller's position and conveyance force based on this feedback, ensuring accurate skew correction only when necessary and preventing multi-feed by avoiding excessive conveyance force on small print media.
2Manufacturing precision
If the pick-up roller is used to overfeed the print medium for skew correction, then skew correction is achieved, but the structure becomes more complex
Solution Approach 1:
The patent applies universality by designing the pick-up roller to serve multiple functions: it acts as both a normal conveyance roller and an additional conveyance roller for skew correction. By making the pick-up roller movable and controllable, the system eliminates the need for separate dedicated components, thus achieving enhanced functionality without proportionally increasing structural complexity.
3Adaptability or versatility
If conveyance force is increased to handle various print medium sizes, then adaptability is improved, but multi-feed occurs on small print media
Solution Approach 1:
The patent applies local quality by differentiating the conveyance force applied to different parts of the print medium based on its size. The movable pick-up roller can be positioned to contact the print medium only when necessary, and the control unit adjusts the conveyance force locally and dynamically. This ensures sufficient force for large print media while avoiding excessive force on small print media that would cause multi-feed.
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
Enables the conveyance of various print media sizes without multi-feed by dynamically controlling conveyance force, ensuring accurate skew correction and preventing abnormal conveyance.
Implementation Method 1
a first conveyance unit that forms a nip portion between a drive roller and a driven roller and is capable of conveying the print medium by pinching the print medium at the nip portion
Implementation Method 2
a feed unit that feeds a print medium
Data Source
AI summary
A technique that enables application of additional conveyance force to a print medium and conveyance of various sizes of print media without multi-feed is described. A conveyance device includes a feed unit, a first conveyance unit that conveys a print medium, and a second conveyance unit that conveys a print medium fed by the feed unit to the first conveyance unit, and is capable of correcting the skew of a print medium by causing the second conveyance unit to convey the print medium with its leading edge in abutment with the first conveyance unit. This conveyance device is configured to cause the feed unit to apply conveyance force to a print medium conveyed by the second conveyance unit, depending on the size of the print medium in the conveyance direction.