Printer Backward Conveyance Roller Separation Mechanism
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Solution Overview
Problem
Printers face the challenge of damaging printing media when conveying sheets upstream, as the media can be pinched between rollers, leading to potential damage during the printing process.
Innovation Solution
A printer design that includes a conveyor system capable of both forward and backward conveyance, with a moving mechanism to adjust the nip load and position of rollers, allowing for controlled backward conveyance to reduce the risk of damage by minimizing the nip load and separating the rollers from the media when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sheet is conveyed upstream in the conveying direction while being nipped by the first roller and the second roller, then the leading-end positioning is achieved, but the sheet may be damaged
Solution Approach 1:
The patent makes the nip load dynamic by moving the first roller between a first position (nipping the sheet) and a second position (separated from the sheet). During backward conveyance for leading-end positioning, the first roller is positioned at the second position to avoid nipping and damaging the sheet. After positioning, the roller moves to the first position to resume normal conveying with appropriate nip load.
Solution Approach 2:
The system performs preliminary action by separating the first roller from the sheet before executing the backward conveyance operation. This preliminary separation prevents damage during the positioning maneuver, and the roller is brought back into contact with the sheet after positioning is complete, restoring normal conveying conditions.
2Reliability
If the nip load is increased to ensure proper conveying control, then the conveying reliability is improved, but the sheet damage risk increases during backward conveyance
Solution Approach 1:
The patent dynamically adjusts the nip load by controlling the position of the first roller. During backward conveyance for leading-end positioning, the nip load is reduced to zero by positioning the first roller at the second position (separated from the sheet). During normal forward conveying, the roller is at the first position providing adequate nip load for reliable conveying control.
3Object-affected harmful factors
If the moving mechanism is added to adjust roller position and nip load, then the sheet damage is reduced during backward conveyance, but the device complexity increases
Solution Approach 1:
The first roller is designed with multi-functionality, serving both as a conveying roller during normal operation and as a movable element that can be separated from the sheet for damage-free backward conveyance. This universal design integrates the damage prevention function into the existing conveying mechanism rather than adding completely separate systems.
Data Source
AI summary
A printer includes: a conveyor that performs a forward-conveyance operation for conveying a printing medium downstream in a conveying direction and a backward-conveyance operation for conveying the printing medium upstream in the conveying direction; a printing device; a roller provided downstream of the conveyor in the conveying direction; an opposed member opposed to the roller; a moving mechanism that moves a moving member, which is one of the roller and the opposed member, between (i) a first position at which the printing medium is nipped between the moving member and the other of the roller and the opposed member and (ii) a second position at which the moving member is separated from the printing medium; and a controller that executes a first conveyor-backward-conveyance processing for controlling the conveyor to perform the backward-conveyance operation in a state in which the moving member is located at the second position.