Fixing Unit Shutter Positioning for Safe Sheet Conveyance
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in precisely positioning shutters due to manufacturing tolerances of interlocking members, leading to potential user safety hazards and reduced sheet conveyance path efficiency.
Innovation Solution
A fixing unit with a pivotable shutter mechanism, supported by a holder and urged by a torsion coil spring, is interlocked with the opening/closing cover to ensure precise positioning at open and closed positions, reducing the risk of user contact with high-temperature components and maintaining a wide sheet conveyance path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shutter is urged toward a closed position by a spring mechanism, then user safety is improved by preventing contact with high-temperature parts, but positioning precision deteriorates due to manufacturing tolerances of interlocking members
Solution Approach 1:
A guide member is introduced as an intermediary component between the shutter and the opening/closing member. The guide member has a guide groove that receives a guide protrusion, forming a sliding mechanism that constrains the shutter's movement path. This intermediary structure compensates for manufacturing tolerances in the interlocking members by providing a precise mechanical guide, thereby achieving accurate shutter positioning while maintaining the spring-based safety mechanism.
2Ease of operation
If the shutter is moved by an interlocking member that moves in an interlocked manner with the opening/closing member, then the shutter can be opened when needed, but positioning precision deteriorates due to manufacturing tolerances
Solution Approach 1:
The guide member acts as a mediator between the interlocking member and the shutter. While the interlocking member provides the driving motion for opening the shutter, the guide member's groove-and-protrusion mechanism ensures that the shutter follows a precise trajectory. This separation of functions allows the interlocking member to handle operation ease while the guide member handles positioning precision, resolving the contradiction between these two requirements.
3Productivity
If the shutter is held at the open position, then sheet conveyance efficiency is improved, but device complexity increases due to additional positioning mechanisms
Solution Approach 1:
The guide member serves multiple functions simultaneously: it guides the shutter's movement, constrains its positioning, and works in conjunction with the spring mechanism. By merging these functions into a single component rather than adding separate mechanisms for each function, the solution improves sheet conveyance efficiency through reliable shutter positioning while minimizing the increase in device complexity.
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 enhances user safety by preventing finger contact with high-temperature parts and minimizes sheet jams, while maintaining a compact printer size and efficient sheet conveyance.
Implementation Method 1
a torsion coil spring that urges the shutter toward the open position
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An image forming apparatus includes an image forming portion configured to form a toner image on a sheet, a fixing portion (300) configured to heat and pressurize the sheet bearing the toner image to fix the toner image to the sheet, a shutter (320) provided to be movable to an open position (P1) at which the shutter (320) opens an opening that the sheet being conveyed toward the fixing portion (300) is able to pass through, and a closed position (P2) at which the shutter (320) closes the opening, an urging portion (340) configured to urge the shutter (320) toward the open position (P1), and an abutment portion (335) that the shutter (320) urged toward the open position (P1) by the urging portion (340) abuts to be positioned at the open position (P1).