Dynamic Sheet Interval Control for Image Formation Accuracy
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Solution Overview
Problem
The existing image forming apparatuses face challenges in maintaining high throughput and accuracy of image formation position while avoiding increased size, particularly when sheet intervals are narrowed, leading to issues like erroneous double feed detection and conveyance errors.
Innovation Solution
The apparatus employs a detection unit to monitor sheet intervals and adjust conveyance speeds dynamically, switching from a first to a second conveyance speed if the leading edge of a sheet is detected later than expected, ensuring the sheet interval is maintained at an ideal value by accelerating or decelerating the sheet conveyance from the registration roller to the transfer unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet interval is narrowed to achieve conventional throughput, then productivity is improved, but reliability deteriorates due to erroneous double feed detection and conveyance errors
Solution Approach 1:
The patent dynamically changes the conveyance speed parameter based on detected sheet feed time variations. When a preceding sheet is fed slower than standard, the system reduces the conveyance speed of the succeeding sheet to prevent timing conflicts, thereby maintaining reliable sheet interval control even with narrowed sheet intervals that enable high throughput
2Productivity
If the sheet interval is narrowed to achieve conventional throughput, then productivity is improved, but manufacturing precision deteriorates due to conveyance errors
Solution Approach 1:
The system dynamically adjusts the conveyance speed parameter based on actual sheet feed timing. By reducing conveyance speed when preceding sheets are fed slower than standard, the patent maintains accurate sheet interval control and prevents conveyance errors, thereby preserving image formation position accuracy even when operating with narrowed sheet intervals for high throughput
3Reliability
If a sheet is temporarily stopped at the registration roller position to make sheet intervals uniform, then reliability is improved, but manufacturing precision deteriorates due to sheet flexure variation
Solution Approach 1:
Instead of temporarily stopping the sheet at the registration roller, the patent dynamically adjusts the conveyance speed of the succeeding sheet based on the feed time of the preceding sheet. This dynamic speed adjustment maintains uniform sheet intervals without causing sheet flexure, thereby preserving image formation position accuracy while achieving reliable sheet interval control
4Manufacturing precision
If a sheet is conveyed at uniform speed from registration roller to transfer nip, then manufacturing precision is improved, but device complexity increases due to extended conveyance section
Solution Approach 1:
The patent maintains uniform sheet interval control by changing the conveyance speed parameter dynamically based on sheet feed timing, rather than extending the conveyance section length. This approach achieves accurate image formation position control without increasing device complexity or requiring additional acceleration sections from the sheet cassette to the registration roller
Data Source
AI summary
An actual sheet interval from a preceding sheet to a succeeding sheet is detected by a top sensor. A registration roller is accelerated or decelerated such that the sheet interval from the preceding sheet to the succeeding sheet is an ideal value by the time that the leading edge of the succeeding sheet reaches a transfer nip part. Note that a time period during which acceleration or deceleration is applied and a sub-scan synchronization signal output timing are determined from the actual sheet interval. Note that a recording sheet P does not stop at the registration roller.