Fixing Device Thermal Equalizer for Uniform Heat Distribution
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Solution Overview
Problem
Existing image forming apparatuses face issues with uneven heat distribution and surface asperities in fixing devices, leading to variations in toner image fixation and potential damage to the fixing belt, resulting in suboptimal image quality and increased risk of paper jams.
Innovation Solution
A novel fixing device incorporating a thermal equalizer with inclined portions that reduce local load on the fixing belt, preventing point contact and ensuring even heat distribution, and a nip formation pad to form a recessed fixing nip, which enhances image separation and reduces surface asperity transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional fixing device is used, then the fixing function is provided, but uneven heat distribution occurs on the fixing belt surface
Solution Approach 1:
The thermal equalizer features an inclined surface at its longitudinal end that contacts the fixing belt at a specific location. This creates a localized heat transfer zone that gradually equalizes temperature across the belt surface, addressing the uneven heat distribution while minimizing surface asperity through the gradual inclination rather than abrupt contact.
Solution Approach 2:
The thermal equalizer acts as an intermediary component between the heat source and the fixing belt. It mediates the heat transfer process by conducting thermal energy from the heating unit to the fixing belt through its inclined surface, thereby achieving more uniform heat distribution and reducing surface asperity effects.
2Temperature
If the fixing belt is pressed against the thermal equalizer, then heat is transferred, but point contact occurs causing surface asperity transfer
Solution Approach 1:
The thermal equalizer employs an inclined surface with a gradual curvature rather than a sharp edge. This curved contact surface distributes the contact area between the fixing belt and thermal equalizer, transforming point contact into line or area contact, thereby preventing surface asperity transfer while maintaining effective heat transfer.
3Device complexity
If the fixing nip is formed without a nip formation pad, then the structure is simpler, but image separation is poor and paper jams occur
Solution Approach 1:
The fixing device is segmented into distinct functional components: the fixing belt, the thermal equalizer, and the nip formation pad. The nip formation pad is specifically positioned to create a recessed fixing nip geometry, which improves image separation from the belt surface after fixing, thereby reducing paper jams while maintaining reasonable structural complexity.
4Ease of manufacture
If the thermal equalizer has a straight edge, then manufacturing is easier, but it causes point contact and belt damage
Solution Approach 1:
Instead of a straight edge, the thermal equalizer incorporates an inclined surface with gradual curvature at its longitudinal end. This curved geometry is easier to manufacture using standard machining or molding processes while simultaneously preventing point contact with the fixing belt, thereby enhancing belt durability without significantly complicating fabrication.
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 effectively addresses uneven heat distribution and surface asperity issues, improving image quality by preventing damage to the fixing belt and reducing paper jams, while maintaining even nip width and enhancing the fixing process efficiency.
Implementation Method 1
a thermal equalizer (5) disposed facing an inner circumferential surface of the fixing rotator (1)
Implementation Method 2
Each of an upstream boundary portion as a boundary between the first face and the second face and a downstream boundary portion as a boundary between the first face and the third face includes, at least in a longitudinal end portion of the thermal equalizer proximate to the pressure gear, an inclined portion inclined to narrow the first face toward a longitudinal end of the thermal equalizer and having an angle of inclination not greater than 3°
Data Source
AI summary
A fixing device includes a fixing rotator, a pressure rotator, a belt holder, a pressure gear, a thermal equalizer, a nip formation pad, and a support. The thermal equalizer includes a first face facing a fixing nip between the fixing rotator and the pressure rotator, and second and third faces bending and extending from upstream end and downstream end, respectively, of the first face in a direction of rotation of the fixing rotator. An upstream boundary portion between the first face and the second face and a downstream boundary portion between the first face and the third face each include, at least in a longitudinal end portion of the thermal equalizer proximate to the pressure gear, an inclined portion inclined to narrow the first face toward a longitudinal end of the thermal equalizer and having an angle of inclination not greater than 3°.