Fixing Device Endless Belt Thermal Stress Management
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face challenges in shortening first print time and reducing energy consumption while minimizing damage to thinner, low-thermal-capacity endless belts, which are prone to breakage due to direct heating methods and friction-related wear.
Innovation Solution
A fixing device with a nip formation assembly featuring a base pad with a pressure portion, extension portion, and curved portion, where the extension portion does not press against the opposed rotary body, and a low-friction sheet to reduce friction and wear, combined with direct heating of the endless belt by a halogen heater, ensuring stable and efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct heating method is used to heat the endless belt, then heating efficiency is improved and first print time is shortened, but the endless belt is prone to breakage due to thermal stress
Solution Approach 1:
A metal thermal conductor is introduced as an intermediary between the heater and the endless belt. The heater heats the metal thermal conductor, which then transfers heat to the endless belt through thermal conduction. This intermediary approach allows efficient heating while distributing thermal stress, preventing direct thermal shock to the belt and reducing breakage.
2Speed
If the endless belt is made thinner to decrease thermal capacity, then heating speed is improved, but mechanical strength is reduced and wear increases
Solution Approach 1:
The metal thermal conductor serves as a protective intermediary that shields the thin endless belt from direct mechanical contact with the pressing roller and other components. This allows the belt to remain thin for fast heating while the intermediary provides the necessary mechanical protection, reducing wear and preventing breakage.
Solution Approach 2:
The endless belt is designed as a thin film structure with decreased thermal capacity to enable rapid heating. The thin film design achieves the desired heating speed while the belt material and construction maintain sufficient mechanical strength for operation.
3Manufacturing precision
If the pressing force is increased to improve fixing performance, then fixing quality is improved, but friction-related wear on the endless belt increases
Solution Approach 1:
The metal thermal conductor acts as a sliding intermediary between the pressing roller and the endless belt. Instead of direct friction between the belt and pressing roller, the thermal conductor mediates the contact, reducing friction-related wear on the belt while still transmitting the necessary pressing force for quality fixing.
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 enables faster heat-up times, reduced energy consumption, and minimized wear and breakage of the endless belt, enhancing the reliability and performance of the fixing device while maintaining efficient image fixation on recording media.
Implementation Method 1
a halogen heater that heats the endless belt directly
Implementation Method 2
stable and efficient heat transfer
Implementation Method 3
a low-friction sheet to reduce friction and wear
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The fixing device (20) includes a nip formation assembly (24) that includes a base pad (241) defining a fixing nip (N) formed between an endless belt (21) and an opposed rotary body (22). The base pad (241) includes a pressure portion (50), an extension portion (51), and a curved portion (52). The pressure portion (50) presses against the opposed rotary body (22) via the endless belt (21). The extension portion (51) is contiguous to and disposed upstream from the pressure portion (50) in a recording medium conveyance direction. The extension portion (51) does not press against the opposed rotary body (22) via the endless belt (21). The curved portion (52) is disposed upstream from the extension portion (51) in the recording medium conveyance direction and smoothly blends into the extension portion (51). The curved portion (52) does not press against the opposed rotary body (22).