Fuser Assembly Thermal Control via AC Power Mapping
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Solution Overview
Problem
Electrophotographic imaging devices face challenges in tightly controlling temperature in the fuser assembly while minimizing power flicker and harmonics, especially with single resistive trace heaters, which generate severe harmonics and flicker when increasing power to meet time-to-first-print criteria, and struggle to maintain temperature control across varying media types.
Innovation Solution
A controller system for the fuser assembly that applies AC power to a resistive trace with a length extending transverse to the process direction, calculating power levels from zero to full power and mapping them to specific heating power levels to achieve desired temperature control, applying power at zero-crossings to minimize flicker and harmonics, using empirically derived power levels and AC half-cycle waveforms to balance temperature control and flicker levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power is increased to meet time-to-first-print criteria, then heating speed is improved, but power harmonics and flicker worsen
Solution Approach 1:
The patent applies periodic action by cycling power through multiple resistive traces in alternating half-cycles of AC power. The controller activates different traces during positive and negative half-cycles, creating a periodic power application pattern that achieves fast heating while canceling harmonics and flicker through the alternating pattern.
Solution Approach 2:
The heating element is segmented into multiple resistive traces that can be independently controlled. The controller selectively activates different traces during different half-cycles, allowing the system to distribute power across multiple segments rather than applying full power to a single trace, thereby reducing harmonics and flicker.
2Object-generated harmful factors
If multiple resistive traces are used to minimize flicker and harmonics, then power control is improved, but device complexity worsens
Solution Approach 1:
The heating element is divided into multiple resistive traces that can be independently controlled. This segmentation allows the controller to apply power to different traces during different half-cycles, achieving flicker and harmonics minimization through distributed power application.
Solution Approach 2:
The system dynamically switches between different resistive traces based on the AC power half-cycle pattern. The controller adapts which trace is active during positive or negative half-cycles, creating a dynamic power distribution strategy that minimizes harmful electrical effects while maintaining heating effectiveness.
3Stability of the object's composition
If power is applied continuously to maintain temperature, then temperature stability is improved, but energy consumption worsens
Solution Approach 1:
The system uses periodic action by cycling power through multiple traces in alternating half-cycles. This periodic power application maintains temperature stability through continuous heating while reducing overall energy consumption compared to continuous full-power operation, as the alternating pattern allows for more efficient heat distribution and reduced peak demands.
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
The solution achieves tight temperature control with minimal power flicker and harmonics, preventing temperature overshoot or undershoot, and meets stringent energy efficiency requirements by optimizing power application to a single resistive trace, enhancing the performance and compliance of imaging devices.
Implementation Method 1
The resistive trace with a length twice extending transverse to the process direction... calculating a power level from zero power (0%) to full power (100%) to heat the trace to a predetermined target or set-point temperature
Data Source
AI summary
An imaging device includes a controller and fuser assembly. The fuser assembly has a heat transfer and backup member defining a nip and process direction of media travel. The heat transfer member includes a resistive trace with a length twice extending transverse to the process direction. The controller selectively applies AC power to the resistive trace. The controller calculates a power level from zero power to full power to heat the trace to a predetermined set-point temperature from a measured current temperature. The controller maps the calculated power level to one of only eight actual heating power levels that become applied or not to the resistive trace to achieve a desired power flicker and harmonics response otherwise unattainable by merely applying the calculated power level. The actual heating power levels include differing numbers of consecutive half-cycles of AC power and are applied at zero-crossings thereof.