Divided Image Heater with Dual-Side Temperature Feedback
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Solution Overview
Problem
Existing image forming apparatuses with divided heaters face challenges in precise temperature regulation due to variance in resistance values and heat generation distribution, leading to issues like faulty fixing and hot offset, especially when handling different sheet sizes.
Innovation Solution
The apparatus employs a heater with symmetrically arranged heat-generating member groups on either side of a conveyance reference, using separate control circuits for each group, and incorporates temperature-detecting elements on both sides to maintain precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a divided heater with multiple heat-generating blocks is used to suppress high temperature at non-sheet-feeding portions, then temperature control adaptability is improved, but temperature regulation precision deteriorates due to resistance variance in heat-generating members
Solution Approach 1:
The heater is divided into multiple heat-generating blocks (first through fifth blocks) arranged in the width direction, each capable of independent power supply control. This segmentation allows selective activation of specific blocks based on sheet size to suppress high temperature at non-sheet-feeding portions while maintaining overall temperature regulation precision through coordinated control of individual blocks.
Solution Approach 2:
Temperature-detecting elements are strategically positioned at specific locations (first and second detection positions) where temperature variance is most likely to occur due to resistance distribution. By focusing detection and control efforts at these critical locations, the system achieves precise temperature regulation despite resistance variance across different heat-generating blocks.
2Measurement precision
If temperature-detecting elements are positioned to monitor specific heat-generating blocks, then temperature regulation precision is improved, but the system becomes vulnerable to resistance variance causing lateral difference in fixability
Solution Approach 1:
The system uses temperature-detecting elements to provide real-time feedback on temperature at critical positions, and the control unit adjusts power supply to heat-generating blocks based on this feedback. This closed-loop feedback mechanism compensates for resistance variance by dynamically adjusting power distribution to maintain uniform temperature and consistent fixability across the entire heating surface.
Solution Approach 2:
The control unit performs multiple functions: it controls power supply to different heat-generating blocks based on sheet size, monitors temperature at multiple positions, and adjusts power distribution to compensate for resistance variance. This multi-functional control approach ensures both temperature regulation precision and fixability consistency under varying operating conditions.
3Device complexity
If common drive circuits are used for multiple heat-generating blocks to reduce apparatus size and cost, then device complexity is reduced, but temperature control precision deteriorates due to inability to independently regulate each block
Solution Approach 1:
Multiple heat-generating blocks are controlled through common drive circuits that can independently regulate power to each block. This merging approach reduces apparatus size and cost by sharing control infrastructure while maintaining the capability to independently control each block's power output, thus preserving temperature control precision through coordinated operation of the unified control system.
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 enables precise temperature regulation, reducing the risk of faulty fixing and hot offset, even with varying sheet sizes, by independently controlling heat distribution based on real-time temperature feedback.
Implementation Method 1
a heater that includes a plurality of heat-generating members arrayed in a width direction of a recording material that is orthogonal to a conveying direction of the recording material
Implementation Method 2
a temperature-detecting portion that detects a temperature of the heater
Data Source
AI summary
In an image heating apparatus, a plurality of heat-generating members that a heater has include a first heat-generating member group and a second heat-generating member group, symmetrically laid out with a conveyance reference position of a recording material. A control portion supplies electric power via first and second common circuits to the first heat-generating member group and the second heat-generating member group. A temperature-detecting portion includes a first temperature-detecting element for detecting a temperature of one of the heat-generating members included in the first heat-generating member group, and a second temperature-detecting element for detecting the temperature of one of the heat-generating members included in the second heat-generating member group. The first temperature-detecting element is placed on one side as to the conveyance reference position in the width direction, and the second temperature-detecting element is placed on other side as to the conveyance reference position in the width direction.