Image Forming Apparatus Reciprocating Sheet Conveyance Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining consistent sheet conveyance intervals during double-side printing, particularly when varying sheet sizes are used, leading to issues like buckling and jamming due to misaligned toner images and sheet conveyance speed fluctuations.
Innovation Solution
The apparatus incorporates a control unit that switches the conveyance direction of sheets in a double-side conveyance path by alternating the rotational direction of a reversing roller, performing reciprocating control to adjust the sheet's arrival time at the transfer portion, thereby aligning the toner image with the sheet edge, preventing buckling and jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet conveyance speed is increased to improve productivity, then the printing efficiency is improved, but the sheet may reach the transfer portion earlier than the toner image, causing misalignment and image quality degradation
Solution Approach 1:
The patent applies dynamics by making the sheet conveyance speed variable rather than constant. The control unit dynamically adjusts the conveyance speed of the sheet based on the estimated time required for toner image formation, ensuring that the sheet arrives at the transfer portion exactly when the toner image is ready, thus maintaining both high productivity and precise image alignment
Solution Approach 2:
The patent implements feedback control by continuously monitoring the sheet conveyance time and comparing it with the toner image formation time. The control unit uses this feedback information to adjust the conveyance speed, creating a closed-loop control system that maintains accurate image-sheet alignment while optimizing printing efficiency
2Manufacturing precision
If the sheet conveyance is paused to maintain constant intervals between sheets, then the image alignment is improved, but the printing productivity decreases due to speed adjustments and pauses
Solution Approach 1:
The patent applies preliminary action by calculating the required sheet conveyance time in advance based on the toner image formation time before the actual transfer process begins. This allows the system to pre-position the sheet at the optimal location, eliminating the need for pauses or speed adjustments during the critical transfer phase, thus maintaining both precision and productivity
Solution Approach 2:
The system dynamically optimizes the conveyance speed profile throughout the printing process, using different speeds at different stages (faster during non-critical phases, precisely controlled during transfer) to minimize pauses while maintaining alignment precision
3Adaptability or versatility
If the conveyance path is switched for double-side printing, then the double-side printing function is enabled, but the sheet may become misaligned with the toner image due to timing differences
Solution Approach 1:
The patent uses feedback control to monitor the sheet's position and conveyance time through the double-side conveyance path. The control unit adjusts the conveyance speed based on real-time feedback, ensuring that even after path switching for double-side printing, the sheet arrives at the transfer portion in precise synchronization with the toner image
Solution Approach 2:
The system performs preliminary calculations to determine the optimal conveyance timing and speed required after switching to the double-side conveyance path. This pre-planning ensures that the sheet is positioned correctly relative to the toner image formation timeline, maintaining alignment precision throughout the double-side printing process
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
This solution ensures stable image quality by preventing sheet misalignment and reducing the need for speed adjustments or motor pauses, thus maintaining efficient operation across different sheet sizes.
Implementation Method 1
the sheet on which the toner image has been transferred is heated to fix the toner image on the sheet
Implementation Method 2
the image forming apparatus of the electrophotographic type which forms an image
Data Source
AI summary
An image forming apparatus includes an image forming unit, a transfer unit and a control unit. The control unit switches between a first control in which the recording material is conveyed in the first direction and a second control in which the recording material is conveyed in a second direction. In performing a double-side printing in which an image is formed on first and second sides, the control unit performs a reciprocating control in which the first and second controls are alternately switched at least one time in a case in which it is predicted that the recording material reaches a transfer portion earlier than a toner image formed by the image forming unit to be transferred onto the second side when the recording material is being conveyed in a double-side conveyance path.