Shutter Positioning Mechanism for Fixing Device Stability
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Solution Overview
Problem
In conventional image-forming apparatuses, the shutter's open state is unstable due to the urging force from the spring maintaining the closed position even when the shutter is open.
Innovation Solution
An image-forming apparatus with a shutter and an urging member that maintains the shutter at either the opening or closing position, ensuring stability by eliminating the spring's urging force when the shutter is open.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an urging spring is used to maintain the shutter at the closed position, then the shutter can be reliably kept closed to prevent contact with the heater, but the urging force continues to act even when the shutter is open, causing the open state to become unstable
Solution Approach 1:
The urging member is divided into two distinct functional portions: a first portion that urges the shutter toward the closed position, and a second portion that urges the shutter toward the open position. This segmentation allows each portion to independently control the shutter stability in its respective state, resolving the contradiction between reliable closing and stable opening.
Solution Approach 2:
The urging member transitions from a static spring that continuously applies force in one direction to a dynamic mechanism where the urging direction changes based on the shutter position. The first and second portions of the urging member are selectively engaged to provide appropriate urging forces for maintaining either closed or open state, making the system adaptive rather than fixed.
2Device complexity
If a single urging spring is used to maintain the shutter at the closed position, then the structure remains simple, but the open state cannot be stably maintained due to continuous urging force
Solution Approach 1:
The urging member serves multiple functions through its two portions: it can maintain the shutter in the closed state using the first portion, maintain the shutter in the open state using the second portion, and the link member can switch between engaging with either portion. This multi-functionality allows a single urging member to provide stable support for both open and closed states without requiring entirely separate mechanisms.
3Object-affected harmful factors
If the urging spring continuously applies force to keep the shutter closed, then safety is improved by ensuring the shutter returns to closed position, but the open state becomes unstable and may close unintentionally
Solution Approach 1:
The second portion of the urging member acts as a counterbalancing force against the first portion. When the link member engages with the second portion, it provides an urging force in the opposite direction to the first portion's closing force, effectively counterbalancing it to maintain the shutter in a stable open state. This prevents unintentional closing while the heater is exposed.
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 stabilizes both the opening and closing states of the shutter, preventing unintended movements and ensuring reliable operation.
Implementation Method 1
an urging member configured to urge the shutter such that: the shutter at the closing position is maintained at the closing position; and the shutter at the opening position is maintained at the opening position
Data Source
AI summary
An image-forming apparatus includes a fixing device, a shutter, and an urging member. The fixing device includes a heater unit, and a pressure unit forming a nipping region in cooperation with the heater unit. The shutter is movable between a closing position for covering a part of the heating unit and an opening position for uncovering the part of the heating unit. The urging member is configured to urge the shutter such that: the shutter at the closing position is maintained at the closing position; and the shutter at the opening position is maintained at the opening position.