Heater Temperature Detection for Nip Uniformity
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Solution Overview
Problem
The image heating apparatus in image forming systems, such as copiers or printers, experiences non-uniform surface pressure and temperature distribution at the nip portion, leading to image defects like poor fixing and hot offset due to inadequate temperature detection and control.
Innovation Solution
The apparatus includes a heater with independently controlled heating blocks, featuring first and second temperature detection elements arranged downstream and upstream respectively in the recording material conveying direction to precisely detect and control temperatures at the nip portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature detection elements are arranged only on the downstream side of the heater, then the temperature control system is simpler, but the temperature at the nip portion cannot be detected with sufficient precision leading to image defects
Solution Approach 1:
The temperature detection function is segmented into multiple elements positioned at different locations (upstream and downstream sides) to comprehensively monitor temperature distribution across the heater surface, enabling precise detection of temperature variations that would otherwise go undetected
Solution Approach 2:
Different regions of the heater surface are monitored by specifically placing detection elements at the upstream and downstream sides, allowing localized temperature measurement at critical positions where temperature variations most significantly impact image quality
2Reliability
If a single temperature detection element is used per heating block, then the device complexity is reduced, but the reliability of temperature detection and control is insufficient
Solution Approach 1:
The temperature detection function is divided into multiple independent detection elements positioned at different locations within each heating block, allowing the system to detect temperature variations and failures more reliably even if one element malfunctions
Solution Approach 2:
Multiple temperature detection elements provide redundant feedback signals that enable the control system to cross-validate temperature measurements and detect anomalies, improving the overall reliability of temperature control
3Adaptability or versatility
If the heater is divided into multiple independently controlled heating blocks, then the temperature control adaptability is improved, but the device complexity increases
Solution Approach 1:
The heater is segmented into multiple independently controllable heating blocks arranged in the longitudinal direction, allowing different regions to be controlled at different temperatures according to the specific requirements of the recording material being processed
Solution Approach 2:
The heating blocks are designed to be independently controllable, enabling dynamic adjustment of temperature distribution across the heater surface based on real-time feedback from temperature detection elements and the current processing requirements
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 more precise temperature control at the nip portion, preventing image defects and ensuring optimal heating performance.
Implementation Method 1
a heater (300) arranged on the inside of the film (202) as a heat source
Implementation Method 2
first temperature detection elements (Ta-1 to Ta-7, Tb-2, Tb-3, Tb-41, Tb-42, Tb-5, and Tb-6) for detecting temperatures of the heating blocks
Implementation Method 3
a pressure roller (208) as a pressure rotating member in contact with the outer surface of the film (202)
Data Source
AI summary
An image heating apparatus includes a heater having a first heating block and a second heating block, a heating rotating member to be heated by the heater, a pressure rotating member forming a nip portion for conveying a recording material between the pressure rotating member and the heating rotating member, first temperature detection elements and second temperature detection elements for detecting temperatures of the first heating block and second heating block respectively at positions farther from a recording material conveyance reference position than the first temperature detection elements. In the image heating apparatus, the first temperature detection elements are arranged on a side downstream of the heater in a recording material conveying direction, and the second temperature detection elements are arranged on upstream of the first temperature detection elements in the recording material conveying direction.