Duplex Image Recording Sheet Slack Control Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In duplex image recording devices, the change in load and conveyance speed when switching from recording on the front to the back surface of a sheet can cause image deterioration due to the shared drive source and transmission mechanism between the first and second roller pairs, leading to potential blurring of images.
Innovation Solution
The device incorporates a control system that manages the conveyance of sheets by the second and third roller pairs to slack the sheet between them, ensuring the trailing end is separated from the second roller pair before the leading end reaches the recording position, thereby maintaining consistent load and speed, and includes a path changing mechanism to switchback-deliver the sheet to the second conveying path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared drive source and drive transmission mechanism are used for both the first and second roller pairs, then device complexity is reduced and cost is lowered, but image quality deteriorates due to load changes and conveyance speed variations during duplex recording
Solution Approach 1:
The patent divides the drive system into two independent drive sources: one dedicated to the first roller pair (conveying sheet through recording portion) and another dedicated to the second roller pair (conveying sheet through reverse conveying path). This segmentation eliminates the load changes and speed variations that occur when a shared drive system switches between different conveying tasks, thereby maintaining consistent conveyance speed and preventing image blurring during duplex recording.
Solution Approach 2:
The patent introduces a sheet conveying control mechanism that acts as an intermediary between the two independent drive sources. This control system coordinates the operation of both roller pairs to ensure smooth sheet transitions and prevent paper jams, while maintaining the benefits of independent drives for image quality.
2Device complexity
If the second roller pair rotates in the same direction as the first roller pair, then device complexity is reduced, but the sheet cannot be properly conveyed through the reverse conveying path, causing conveyance failure
Solution Approach 1:
The patent makes the rotation direction of the second roller pair dynamic rather than fixed. The second roller pair can rotate in the same direction as the first roller pair during normal conveying, but can reverse direction when needed to properly convey the sheet through the reverse conveying path. This dynamic adjustment capability ensures reliable sheet conveyance while maintaining relatively simple device structure.
3Productivity
If the sheet is forcibly pulled out from the second roller pair by the third roller pair, then the sheet can be conveyed to the first conveying path, but load changes and speed variations cause image blurring
Solution Approach 1:
The patent implements a feedback control mechanism that monitors the position and state of the sheet during conveyance. When the sheet approaches the transition point between the second and first conveying paths, the control system adjusts the rotation speed and torque of the roller pairs to ensure smooth transitions without sudden pulls or jerks. This feedback control maintains constant conveyance speed, preventing image blurring while ensuring efficient sheet movement.
Data Source
AI summary
An image recording device, including: a first sheet conveying path; a recording portion to record an image on a sheet; a first roller pair to convey the sheet in a first direction; a second sheet conveying path; a path changing portion; a second roller pair to convey the sheet in a second direction; a third roller pair to convey, to the first path, the sheet that has been conveyed to the second conveying path; and a control portion to control a sheet conveyance rate by the second roller pair to be higher than that by the third roller pair, whereby a part of the sheet between the second and third roller pairs is slacked for separating, from the second roller pair, a trailing end of the sheet before a leading end thereof reaches a position where the leading end is opposed to the recording portion in the first conveying path.