Fixing Belt Nip Formation Pad Curvature for Separation and Heating
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Solution Overview
Problem
Conventional fixing devices in image forming apparatuses face challenges in ensuring sufficient heating of recording media due to a small fixing nip length, which affects the separability and fixability of images, as the separation angle between the fixing belt and the conveyance direction is increased, leading to inadequate contact between the pressure member and the downstream portion of the fixing belt.
Innovation Solution
The design incorporates a nip formation pad with a second nip forming portion that is curved toward the pressure roller, allowing for a larger separation angle and maintaining a sufficient fixing nip length by ensuring contact between the fixing belt and the pressure roller, even downstream, thus enhancing both separability and fixability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bent portion is disposed downstream from the fixing nip to increase the separation angle, then the separability of the recording medium is enhanced, but the fixing nip length becomes small causing insufficient heating
Solution Approach 1:
The nip formation pad is divided into multiple functional portions: a first nip forming portion that contacts the pressure member to form the fixing nip, a bent portion that changes the conveyance direction to increase separation angle, and a second nip forming portion that extends downstream to maintain fixing nip length. This segmentation allows each portion to fulfill its specific function independently, resolving the contradiction between separation angle and fixing nip length.
Solution Approach 2:
The nip formation pad extends in the conveyance direction (downstream) to add length in another dimension. By extending the pad downstream beyond the bent portion, the fixing nip length is maintained even though the bent portion creates a separation angle. This dimensional extension allows both separation and sufficient heating to occur simultaneously.
2Ease of operation
If the bent portion is disposed downstream from the fixing nip to increase the separation angle, then the separability of the recording medium is enhanced, but the heating efficiency deteriorates
Solution Approach 1:
The heating function is segmented and extended downstream along with the second nip forming portion. The heat generation member heats the fixing belt over an extended region that includes the area downstream of the bent portion, ensuring that sufficient heating occurs despite the separation angle created by the bent portion.
Solution Approach 2:
The heating zone is extended in the conveyance direction to match the extended fixing nip length. By providing heat generation in the downstream region where the second nip forming portion maintains contact, the heating efficiency is maintained even with the increased separation angle configuration.
3Use of energy by moving object
If the nip formation pad is extended downstream to maintain fixing nip length, then the heating efficiency is improved, but the device complexity increases
Solution Approach 1:
The second nip forming portion serves multiple functions: it maintains the fixing nip length for sufficient heating, guides the fixing belt downstream, and works in conjunction with the bent portion to maintain proper separation. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The nip formation pad integrates multiple functions into a single continuous structure that includes the first nip forming portion, bent portion, and second nip forming portion. By merging these functions into one integrated pad rather than separate components, the overall device complexity is minimized while achieving the desired heating and separation performance.
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 allows for improved separability of the recording medium from the fixing belt while maintaining a sufficient fixing nip length, ensuring effective heating and image fixation, thereby addressing the limitations of conventional designs.
Implementation Method 1
a halogen heater (31) that heats the fixing belt (22) from an inner side
Implementation Method 2
the elastic layer having a thickness of about 100 micrometers elastically deforms to absorb slight surface asperities
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fixing device (7) includes a fixing belt (22), a pressure member (23), a nip formation member (32), a heater (31), and a support (33). The nip formation member (32) includes a first nip forming portion (32a) to contact the pressure member via the fixing belt; a second nip forming portion (32e) downstream from the first nip forming portion in a direction (C1, C2) of conveyance of a recording medium, to contact the pressure member via the fixing belt; an inflection portion (32d) at which a direction of extension of the nip formation member changes; and a supported portion (32c) disposed downstream from the first nip forming portion in the direction of conveyance and supported by the support. The inflection portion is disposed at a position of or downstream from the supported portion in the direction of conveyance. The second nip forming portion is disposed downstream from the inflection portion.