Duplex Image Formation With Dual Sheet-Position Detection
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Solution Overview
Problem
Existing image forming apparatuses require mechanisms to shift registration rollers in the width direction, increasing size and cost, and have inefficient detection systems that lead to misalignment of toner images on sheet surfaces.
Innovation Solution
An image forming apparatus with first and second detecting portions to accurately detect sheet positions, allowing a control portion to adjust image forming positions based on these detections, eliminating the need for physical shifting mechanisms and maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanisms are added to shift registration rollers in the width direction, then sheet positioning accuracy is improved, but device complexity and size increase
Solution Approach 1:
The patent replaces the mechanical registration roller shifting mechanism with an optical detection system combined with digital image processing. The sheet position is detected by sensors and corrected by adjusting the image writing position on the photosensitive member through coordinate transformation, eliminating the need for mechanical shifting components.
Solution Approach 2:
The patent introduces an intermediary control system that mediates between sheet detection and image formation. The control portion receives detection signals from the sheet position detection sensors, calculates the deviation, and adjusts the image writing position accordingly, serving as a mediator that eliminates the need for direct mechanical intervention.
2Measurement precision
If detection sensors are positioned far from the transfer portion, then sheet position detection accuracy is improved, but device size increases
Solution Approach 1:
The patent transitions from spatial separation (positioning sensors far from the transfer portion) to temporal-spatial coordination (detecting sheet position at multiple points along the conveyance path and using control timing to achieve accurate positioning). By detecting sheet position at the transfer portion and coordinating with image writing timing, the system achieves high precision without increasing device footprint.
Solution Approach 2:
The patent performs preliminary detection of sheet position by the first detection sensor before the sheet reaches the transfer portion, and uses this information to pre-calculate and adjust the image writing position. This preliminary action allows the system to compensate for sheet position deviations in advance, ensuring accurate alignment at the transfer portion.
3Manufacturing precision
If registration rollers are shifted mechanically, then toner image alignment is improved, but production cost increases
Solution Approach 1:
The patent replaces expensive mechanical registration roller shifting mechanisms with cost-effective optical sensors and digital control systems. The sheet position is detected by sensors and corrected by adjusting image writing coordinates through software processing, eliminating the need for costly mechanical components and their associated actuators.
Solution Approach 2:
The patent creates a digital copy of the sheet position information through sensors and uses this copied data to calculate and adjust the image writing position. Instead of physically moving components, the system copies the position information and applies corrective transformation to the image data, significantly reducing hardware costs.
Data Source
AI summary
An image forming apparatus includes a re-conveyance portion to reverse a sheet on which a first toner image is transferred on a first surface by a transfer portion and to convey the sheet to the transfer portion again, and first and second detecting portions to detect positions in a widthwise direction of the sheet. The first detecting portion detects a first detecting position before the first toner image is transferred to the first surface and the second detecting portion detects a second detecting position after the first toner image is transferred and before a second toner image is transferred on a second surface. A controller determines a first image forming position where a latent image is formed on a photosensitive member before the first detecting position is detected and determines a second image forming position based on the first image forming position, and the first and second detecting positions.