Image Forming Apparatus Double-Sided Conveyance Dew Condensation Control
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Solution Overview
Problem
Dew condensation occurs in image forming apparatuses during double-sided printing due to water vapor discharge, causing image defects, especially in winter or low temperature conditions, and existing solutions are costly and inefficient as they rely on a single standby position which cannot effectively manage varying air permeance of different materials.
Innovation Solution
The image forming apparatus includes a double-sided conveyance path with multiple standby positions downstream of the fixing unit, where the sheet is stopped for varying times based on the material's air permeance to prevent dew condensation, allowing the sheet to be stopped at a first and second position with adjusted stopping times to manage water vapor discharge effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single standby position is used for sheets during double-sided printing, then the sheet can be stopped to allow water vapor discharge, but the sheet remains at the same position for too long causing dew condensation and image defects
Solution Approach 1:
The single standby position is segmented into multiple standby positions (first standby position and second standby position) arranged in the sheet conveyance direction. The sheet is stopped at the first standby position for a first stopping time, then conveyed to the second standby position for a second stopping time. This segmentation allows the total stopping time to be divided into multiple shorter intervals, preventing dew condensation while maintaining adequate time for water vapor discharge.
2Object-affected harmful factors
If the sheet is stopped for a long time at one position to allow water vapor discharge, then dew condensation is prevented, but productivity is lowered
Solution Approach 1:
The long stopping time at a single position is segmented into multiple shorter stopping times at different positions. The sheet stops at the first standby position for a first stopping time, then is briefly conveyed to the second standby position, and stops again for a second stopping time. This segmentation reduces the continuous stopping time, allowing productivity to be maintained while still providing adequate total time for water vapor discharge and preventing dew condensation.
3Object-affected harmful factors
If a cooling unit is provided at the standby position to prevent dew condensation, then image defects are prevented, but the cost increases
Solution Approach 1:
Instead of providing a cooling unit at the standby position, the invention segments the stopping process into multiple positions with adjusted stopping times. By controlling the sheet to stop at the first standby position for a first stopping time and then at the second standby position for a second stopping time, the system prevents dew condensation through time management rather than active cooling, thereby avoiding the additional cost of cooling equipment.
Solution Approach 2:
The invention replaces the mechanical/thermal system (cooling unit) with a control system that manages sheet conveyance and stopping times. By using the conveyance mechanism itself to create multiple stopping positions and adjust stopping times based on sheet material, the system achieves dew condensation prevention without requiring additional cooling hardware, thus reducing apparatus cost.
4Device complexity
If the stopping time is fixed for all sheet materials, then the control is simple, but dew condensation occurs for materials with different air permeance
Solution Approach 1:
The stopping times are made dynamic rather than fixed. The control unit adjusts the first stopping time at the first standby position and the second stopping time at the second standby position based on the air permeance of the sheet material. For materials with high air permeance, longer stopping times are provided, while for materials with low air permeance, shorter stopping times suffice. This dynamic adjustment prevents dew condensation across different materials without requiring overly complex control mechanisms.
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 effectively reduces dew condensation without lowering productivity, as the adjusted stopping times and multiple positions account for different materials' air permeance, preventing image defects while maintaining efficient operation.
Implementation Method 1
dew condensation occurs due to water vapor discharged from the sheet
Implementation Method 2
dew condensation occurs due to water vapor discharged from the sheet
Data Source
AI summary
An image forming apparatus includes an image forming unit configured to form a toner image on a sheet, a fixing unit configured to fix the toner image on the sheet, a double-sided conveyance path along which the sheet is conveyed for double-sided printing, and a control unit configured to control conveyance of the sheet, allowing the sheet to be stopped at a first standby position which is more downstream than the fixing unit in a sheet conveyance direction on the double-sided conveyance path and a second standby position which is more downstream than the first standby position, and changing stopping time for which the sheet is stopped at the first standby position and stopping time for which the sheet is stopped at the second standby position according to a material of the sheet.