Movable Heat Shield with Reinforcement for Fixing Rotary Body
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face overheating issues due to non-conveyance spans on the fixing rotary body, leading to energy wastage and potential mechanical strength degradation when using heat shields with increased thermal capacity, and those with decreased thermal capacity compromise mechanical strength.
Innovation Solution
A movable heat shield with a reinforcement is integrated between the heater and the fixing rotary body, featuring a narrow portion and a bridge with a reinforcement to enhance mechanical strength, allowing it to be positioned between the heater and the fixing rotary body to shield it effectively while maintaining efficient heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat shield has an increased thermal capacity to prevent overheating, then the overheating problem is solved, but energy is wasted as the heat shield absorbs heat from the heater unnecessarily
Solution Approach 1:
The heat shield is made movable rather than fixed, allowing it to dynamically adjust its position between the heater and fixing rotary body. It can be moved closer to the heater when overheating is detected and retracted when not needed, optimizing both temperature control and energy efficiency.
Solution Approach 2:
The heat shield is divided into multiple sections (first heat shield and second heat shield) that can move independently or in coordination, allowing selective shielding of different portions of the fixing rotary body to minimize energy waste while preventing overheating.
2Loss of energy
If the heat shield is made into a thin plate to decrease thermal capacity and reduce energy absorption, then energy efficiency is improved, but the mechanical strength of the heat shield degrades
Solution Approach 1:
The heat shield employs a composite structure combining a thin plate base material with reinforcing elements (such as ribs or strengthening portions). This allows the heat shield to maintain low thermal capacity from the thin plate while gaining mechanical strength from the reinforcement structures.
Solution Approach 2:
The heat shield has non-uniform thickness or incorporates localized reinforcement portions at critical areas (such as attachment points or high-stress regions), maintaining thin construction overall for low thermal capacity while providing localized strength where mechanically necessary.
3Loss of energy
If the heat shield is made movable to optimize heat management, then energy efficiency and temperature control are improved, but the device complexity increases
Solution Approach 1:
The movable heat shield mechanism replaces complex mechanical actuation systems with simpler control methods, such as thermal expansion elements, bimetallic strips, or controlled by straightforward actuators that respond directly to temperature conditions without requiring complex control systems.
Solution Approach 2:
The heat shield is designed to move automatically in response to thermal conditions, using the heat itself to drive the movement (e.g., through thermal expansion differences or bimetallic action), eliminating the need for external motors or complex control mechanisms.
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 prevents overheating of the fixing rotary body, conserves energy, and enhances the mechanical strength of the heat shield, ensuring precise temperature control and reliable operation during the image fixing process.
Implementation Method 1
a fixing rotary body heated by a heater
Implementation Method 2
a heat shield movable in a circumferential direction of the fixing rotary body and interposed between the heater and the fixing rotary body to shield the fixing rotary body from the heater
Implementation Method 3
the fixing rotary body heated to a predetermined fixing temperature and the opposed body together heat and melt toner of the toner image
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A fixing device (20; 20S) includes a fixing rotary body (21) and an opposed body (22) contacting the fixing rotary body (21) to form a fixing nip (N) therebetween through which a recording medium is conveyed. A heat shield (27; 27S) is interposed between the heater (23) and the fixing rotary body (21) to shield the fixing rotary body (21) from the heater (23). A driver (46) drives and moves the heat shield (27; 27S) between a shield position where the heat shield (27; 27S) is interposed between the heater (23) and the fixing rotary body (21) to shield the fixing rotary body (21) from the heater (23) and a retracted position where the heat shield (27; 27S) is retracted from the shield position. A reinforcement (53; 53S; 53T; 53U) is mounted on a long edge of the heat shield (27; 27S).