Variable Sheet Discharge Speed for Fixing Unit Contamination Control
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Solution Overview
Problem
Existing image forming apparatuses face issues with residual sheets getting stuck in the conveyance path, leading to toner image fixation failures and contamination of the fixing unit when discharging sheets after a jam, as they rely on heating the fixing roller to a predetermined temperature before discharge.
Innovation Solution
The apparatus incorporates a control unit that adjusts the conveyance speed of the sheet based on the temperature of the fixing unit and the position of the sheet relative to the fixing nip, ensuring the sheet passes through the fixing nip when the unit has reached a temperature sufficient for proper toner fixation, thereby preventing toner adherence to the fixing unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fixing roller is heated to a predetermined temperature before sheet discharge, then toner image fixation is ensured, but the discharge time is extended and productivity is reduced
Solution Approach 1:
The patent applies dynamics by making the conveyance speed variable rather than fixed. The control unit dynamically adjusts the conveyance speed of the sheet based on the detected temperature of the fixing unit and the position of the sheet. When the fixing unit temperature is insufficient, the sheet is conveyed slower to allow heating time; when temperature is sufficient, normal speed is restored. This dynamic speed adjustment resolves the contradiction between ensuring fixation reliability and maintaining discharge productivity.
Solution Approach 2:
The patent changes the parameter of conveyance speed based on the temperature parameter of the fixing unit. By detecting the fixing unit temperature and using it to determine the appropriate conveyance speed, the system adapts the discharge process to the actual thermal state. This parameter-based control allows the system to optimize both fixation quality and discharge efficiency under different temperature conditions.
2Productivity
If the sheet is conveyed quickly through the fixing unit, then productivity is improved, but toner may adhere to the fixing unit causing contamination
Solution Approach 1:
The patent implements feedback control by using a temperature detection unit to continuously monitor the fixing unit temperature and using this information to control the conveyance speed. The control unit receives temperature feedback and adjusts the sheet conveyance accordingly. This closed-loop feedback mechanism ensures that sheets are only conveyed quickly when the fixing unit is sufficiently hot, preventing toner contamination while maintaining high productivity when conditions permit.
3Device complexity
If a single motor controls both fixing and conveying devices, then device complexity is reduced, but control precision for simultaneous temperature and position management becomes more difficult
Solution Approach 1:
The patent applies universality by using a single motor to perform multiple functions - both driving the fixing roller and controlling sheet conveyance. This multi-functional approach simplifies the mechanical structure and reduces the number of components. The control unit coordinates these different functions by integrating temperature detection and position control algorithms, managing the complexity of controlling a single motor that performs multiple roles.
Solution Approach 2:
The patent substitutes mechanical control with electronic/digital control. Instead of using separate mechanical mechanisms for fixing and conveying, the system uses a single motor controlled by electronic signals from the control unit. The control unit processes temperature data and position information electronically to generate appropriate motor control signals, replacing complex mechanical coordination with flexible electronic control.
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 approach effectively discharges residual sheets without toner fixation failures, reduces contamination of the fixing unit, and simplifies control by using a single motor for both the fixing and conveying devices, enhancing operational efficiency and reducing costs.
Implementation Method 1
a fixing unit that heats and pressurizes the sheet at a nip portion to fix the toner image formed by the image forming unit to the sheet
Data Source
AI summary
An image forming apparatus includes a control unit configured to execute a sheet discharge mode. If a case where a distance between the leading edge and the nip portion is a first distance is a first case, and a case where a distance between the leading edge of the sheet and the nip portion is a second distance shorter than the first distance and the temperature detected by the temperature detection unit is the same as that in the first case is a second case, the control unit is configured to set a conveyance speed of the sheet in discharging the sheet toward the nip portion in the second case to be slower than that in the first case, in the sheet discharge mode.