Fuser Pressure Mechanism With Cam-Swing Plate for Stable Nip Force

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Solution Overview

Problem

Existing fixing devices in electrophotographic image forming apparatuses face challenges in stabilizing contact pressure between heating and pressure members, often requiring complex and costly mechanisms.

Innovation Solution

A fixing device with a pressure mechanism that includes a pressure plate, biasing member, cam member, and support member, which adjusts contact pressure through a compact, low-cost configuration, using a swingable pressure plate and cam mechanism to stabilize the contact between the heating and pressure members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complex pressure mechanism is used to stabilize contact pressure, then contact pressure stability is improved, but device complexity increases

Engineering Contradiction:
Improvecontact pressure stabilityVSAvoidmechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pressure plate is designed to swing dynamically between contacting and separating from the heating member, allowing automatic adjustment of contact pressure. This dynamic mechanism replaces complex static pressure control systems, achieving stable contact pressure through the natural swing motion driven by the biasing member and cam member interaction.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The pressure mechanism uses the swing motion of the pressure plate itself to regulate contact pressure. The biasing member provides continuous biasing force, and the cam member converts rotational motion into the swinging motion of the pressure plate, creating a self-regulating system that maintains stable contact pressure without external control mechanisms.

Inventive Principle:
Principle #25Self-service

2Device complexity

If a simple pressure mechanism is used, then device complexity is reduced, but contact pressure stability deteriorates

Engineering Contradiction:
Improvemechanism complexityVSAvoidcontact pressure stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The cam member acts as an intermediary between the biasing member and the pressure plate. It converts the continuous biasing force from the spring into controlled swinging motion of the pressure plate, enabling stable contact pressure regulation with a simple mechanical structure. The cam profile determines the swing amplitude and timing, providing precise control without complex mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cam member utilizes curved surfaces to transform rotational motion into the swinging motion of the pressure plate. The curved profile of the cam converts the continuous rotation into periodic contact and separation of the pressure plate, achieving stable contact pressure through geometric curvature rather than complex mechanical linkages.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Volume of moving object

If a compact design is used, then device size is reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improvefixing device sizeVSAvoidcomponent precision
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The pressure mechanism is divided into distinct functional components: the pressure plate for contact pressure application, the biasing member for providing continuous force, the cam member for motion conversion, and the support member for structural support. This segmentation allows each component to be manufactured with standard precision using conventional processes, while the assembled mechanism achieves compact dimensions and stable contact pressure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The support member serves multiple functions: it supports the swing fulcrum of the pressure plate, provides mounting positions for the biasing member and cam member, and maintains the spatial relationships between components. This multi-functionality reduces the number of separate parts needed, enabling a compact design without requiring ultra-precise manufacturing of individual components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 provides stable and consistent contact pressure between the heating and pressure members, enhancing the fixing process efficiency while maintaining a simple and cost-effective design.

Implementation Method 1

The biasing member biases the pressure plate in an approaching direction with respect to one of the heating member and the pressure member

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The cam member contacts the pressure plate on a side opposite to the biasing member, and rotates to cause the pressure plate to swing

Methodology Applied
Scientific EffectCam mechanism: Cam

Data Source

PatentEP4636503B1Fixing device and image forming apparatus
Publication Date: 2026.03.18 KYOCERA DOCUMENT SOLUTIONS INC
  • EP4636503B1 patent drawingFigure 1
  • EP4636503B1 patent drawingFigure 2
  • EP4636503B1 patent drawingFigure 3

AI summary

A fixing device (30) includes a heating member (32), a pressure member (33), a pressure mechanism (40), and a fixing frame (31). The pressure mechanism (40) includes a pressure plate (41), a biasing member (42), a cam member (43), and a support member (44). The pressure plate (41) swings in an approaching direction and a separating direction with respect to one of the heating member (32) and the pressure member (33). The biasing member (42) biases the pressure plate (41) in the approaching direction with respect to one of the heating member (32) and the pressure member (33). The cam member (43) contacts the pressure plate (41) on a side opposite to the biasing member (42) and rotates to cause the pressure plate (41) to swing. The support member (44) is secured to the fixing frame (31) and supports one end of the biasing member (42) and a swing fulcrum of the pressure plate (41). The support member (44) has a through hole (44h) in which a rotation axis (43x) of the cam member (43) is inserted.