Fixing Device Pressure Control for Wrinkle Prevention
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Solution Overview
Problem
Image forming apparatuses face challenges in fixing toner images on special sheets without causing wrinkles, as existing technologies often compromise fixability when adjusting for different sheet types.
Innovation Solution
An image forming apparatus with a fixing device that includes a pressure-applying mechanism with adjustable pressure positions and a reference position detection mechanism, allowing for precise control of fixing nip pressure based on the type of recording medium, using a pressure-applying lever, pressing cam, and drive motor to vary pressure and position the pressure-applying rotary member accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure contact force is increased to improve toner fixability, then fixing quality improves, but wrinkle formation increases on special sheets
Solution Approach 1:
The fixing device dynamically adjusts the pressure contact force between the fixing roller and pressure-applying roller based on the detected thickness of the recording material. The pressure-applying mechanism includes a pressure-applying lever and pressing cam that can vary the pressure contact force, transitioning from a fixed pressure system to an adaptable dynamic pressure system that optimizes both fixability and wrinkle prevention
Solution Approach 2:
The system changes the pressure parameter (pressure contact force) according to the thickness parameter of the recording material. By detecting thickness variations and correspondingly adjusting pressure levels, the system adapts fixing conditions to match material properties, resolving the contradiction between maintaining sufficient pressure for fixation and reducing excessive pressure that causes wrinkles
2Object-affected harmful factors
If pressure contact force is decreased to prevent wrinkles on special sheets, then wrinkle formation reduces, but toner fixability deteriorates
Solution Approach 1:
The system adjusts the pressure parameter based on material thickness detection. For special sheets with larger thickness, the system decreases pressure to prevent wrinkles while maintaining adequate pressure for fixation. This parameter adaptation ensures both wrinkle prevention and sufficient fixability are achieved simultaneously
Solution Approach 2:
The fixing device incorporates a recognition unit that detects recording material thickness and provides feedback to the pressure-applying mechanism. This closed-loop control allows the system to automatically adjust pressure contact force based on real-time material properties, ensuring optimal balancing between wrinkle prevention and toner fixation quality
3Reliability
If fixing conditions are optimized for plain sheets, then toner fixability improves, but adaptability to special sheets deteriorates
Solution Approach 1:
The fixing device transitions from static fixed pressure conditions to dynamic adjustable pressure conditions. The pressure-applying mechanism can adapt its pressure contact force based on detected material thickness, enabling the system to optimize fixing conditions for different sheet types including both plain sheets and special sheets
Solution Approach 2:
The fixing device achieves multi-functionality by incorporating thickness detection and pressure adjustment capabilities. A single fixing device can handle multiple sheet types (plain sheets, envelopes, thick sheets) by automatically adapting its pressure contact force, eliminating the need for separate fixing systems for different materials
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 both effective fixability and sheet conveyance capability by accurately adjusting fixing nip pressure for various sheet types, preventing wrinkles and ensuring reliable image formation across different media.
Implementation Method 1
a light blocking plate that is secured to the shaft and a reference position detection sensor that is brought to an on-state or an off-state by the light blocking plate
Implementation Method 2
a heat-applying portion that heats the rotary member to be heated
Data Source
AI summary
An image forming apparatus includes an image forming portion, a fixing device, an input portion, and a control portion. The fixing device includes a rotary member to be heated, a pressure-applying rotary member, a heat-applying portion, a pressure-applying mechanism, and a reference position detection mechanism. The control portion controls fixing processing, with the pressure-applying rotary member disposed at any of a plurality of pressure-applying positions and a pressure reduction position based on a type of the recording medium inputted through the input portion. The control portion performs control so that when a prescribed amount of time has elapsed or when a rotation amount of a shaft has reached a prescribed amount from timing at which a reference position detection sensor is brought to an on-state, the pressure-applying drive motor is stopped so as to dispose the pressure-applying rotary member at any of the plurality of pressure-applying positions.