Fixing Unit Dual Heater Roller Temperature Control
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Solution Overview
Problem
Conventional fixing units in image forming apparatuses experience temperature drops at the ends of the heated roller during standby mode and temperature rises during continuous paper feed, leading to potential fixing failures and generation of Ultra-Fine Particles (UFPs.
Innovation Solution
A fixing unit with two heaters, where the first heat source generates more heat at the ends than the center, and the second heat source generates less overall heat but more at the ends, with a higher rate of heat generation at the ends compared to the center, to maintain consistent temperatures during paper feed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single heater is used in the heated roller, then the device complexity is reduced, but temperature drop at the ends of the roller occurs during standby mode leading to fixing failures
Solution Approach 1:
The heater is divided into multiple independent heating elements (first heater and second heater) with different heat generation characteristics. Each heater segment targets specific regions of the roller - the first heater provides overall heating while the second heater specifically addresses end-region temperature drops, thereby resolving the contradiction between simple device structure and reliable fixing quality.
Solution Approach 2:
Different heater segments are designed with non-uniform heat generation distributions tailored to local temperature requirements. The first heater has higher heat generation at ends to prevent temperature drop, while the second heater provides complementary heating. This local optimization ensures reliable fixing quality across the entire roller surface without requiring a complex single-heater design.
2Reliability
If the heater ON time is extended to prevent temperature drop, then the fixing reliability is improved, but temperature rise at the ends of the roller occurs during continuous paper feed generating UFPs
Solution Approach 1:
Instead of extending the heater ON time continuously, the system employs periodic switching between the first heater and second heater based on operational mode (standby vs. print mode). During standby, the first heater operates periodically to maintain temperature. During print mode, the second heater activates to prevent end-region overheating and UFP generation, thus maintaining fixing reliability while eliminating harmful emissions.
Solution Approach 2:
The system changes operational parameters by switching between different heater configurations based on operational conditions. The first heater with higher end-region heat generation is activated during standby to prevent temperature drop, while the second heater with balanced heat distribution is used during printing to prevent UFP generation. This dynamic parameter adjustment resolves the contradiction between fixing reliability and UFP reduction.
3Reliability
If light distribution at the ends of the heater is increased to prevent temperature drop, then the fixing reliability is improved, but the maximum consumption power increases
Solution Approach 1:
The heating function is segmented into two independent heaters with different power characteristics. The first heater is designed with higher light distribution at ends for preventing temperature drop, while the second heater provides supplemental heating with lower overall power consumption. By switching between these segments based on operational mode, the system achieves reliable fixing quality without continuously operating at maximum power.
Solution Approach 2:
Instead of using a single heater at full power continuously, the system applies partial heating action by switching between the first heater (with enhanced end-region heating) during standby and the second heater (with balanced heating) during printing. This partial action approach maintains fixing reliability while avoiding excessive power consumption that would occur with continuous high-power operation.
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 configuration minimizes temperature drops at the start of paper feed and reduces temperature rises during continuous paper feed, preventing fixing failures and minimizing UFP generation.
Implementation Method 1
a first heat source configured to heat any one of the rollers, the first heat source having an amount of heat generated higher in ends of the first heat source than in a center thereof
Implementation Method 2
a second heat source configured to heat any one of the rollers, the second heat source having an amount of heat generated higher in ends of the second heat source than in a center thereof, and the second heat source having a rate of the amount of heat generated in the ends of the second heat source to that in the center thereof higher than a rate of the amount of heat generated in the ends of the first heat source to that in the center thereof
Implementation Method 3
a fixing unit for applying heat to a recording sheet passing through two rollers contacting each other to fix toner onto the recording sheet
Data Source
AI summary
A fixing unit includes a first heat source configured to heat a roller, and a second heat source configured to heat the roller. The maximum value of a total amount of heat generated in the second heat source is smaller than that of the first heat source. The second heat source has an amount of heat generated higher in ends of the second heat source than in a center thereof in a distribution of the amount of heat generated in the axial direction. The second heat source has a rate of the amount of heat generated in the ends of the second heat source to that in the center thereof higher than a rate of the amount of heat generated in the ends of the first heat source to that in the center thereof.