Image Forming Apparatus Torque Control for Magnification Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image magnification ratio varies during continuous operation, especially when changing trays, due to torque load fluctuations caused by lubricant saturation and sheet type changes, leading to inconsistent image quality.
Innovation Solution
An image forming apparatus with a hardware processor that adjusts the transfer unit's pressure and torque control, using feedback mechanisms to maintain constant-speed and constant-torque operations, and an adjustment mechanism to reduce pressure when load torque exceeds thresholds, ensuring consistent image magnification across multiple sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If constant-speed control is used for the transfer unit, then the transfer unit rotates at a constant speed, but torque applied to the image carrier varies between cycles causing speed variation and image formation accuracy deterioration
Solution Approach 1:
The patent changes the control parameter from constant-speed control to constant-torque control during the pressed state. By detecting the drive torque and maintaining it constant, the system prevents torque variation that would otherwise cause image carrier speed variation and image formation errors, while still achieving consistent transfer performance.
2Manufacturing precision
If constant-torque control is performed while the transfer unit is pressed against the image carrier, then torque variation is reduced, but the transfer load varies over time causing image magnification ratio variation
Solution Approach 1:
The patent implements dynamic adjustment of the torque command value based on real-time detection of transfer load variations. The system continuously monitors the drive torque and adjusts the torque command to compensate for load changes caused by paper sheet passage, thereby maintaining constant image magnification ratio despite varying transfer conditions.
Solution Approach 2:
The patent employs feedback control by detecting the actual drive torque during transfer operations and using this information to adjust the torque command value. This closed-loop control system compensates for transfer load variations and maintains consistent image magnification ratio across multiple sheets.
3Productivity
If the transfer unit is pressed against the image carrier for continuous transfer operations, then productivity increases, but lubricant saturation causes torque load increase and speed variation
Solution Approach 1:
The patent uses feedback control to detect torque load increases caused by lubricant saturation during continuous operations. By monitoring the drive torque in real-time and adjusting the torque command accordingly, the system maintains consistent transfer unit speed and image formation quality even after prolonged operation without separation.
Data Source
AI summary
Provided is an image forming apparatus including an image carrier, a transfer unit, a driver, a hardware processor, an adjustment mechanism, and a speed detector. The hardware processor sets a command value. The hardware processor performs a constant-torque control based on a constant-speed drive torque detected in a constant-speed control. In the constant-torque control, the hardware processor performs a feedback control to set a reference value to an average speed of the driver during passage of a first sheet and calculate a difference from an average speed during passage of a subsequent sheet so as to derive the command value. The hardware processor determines whether a load torque increase, its factor, and/or its influence exceeds a threshold, and forcibly sets the reference value to a speed detected while a pressure between the transfer unit and the image carrier is reduced by the adjustment mechanism from the pressure during image transfer.