Fixing Apparatus Rotation Detection Circuit Heat Suppression
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Solution Overview
Problem
Existing heat fixing apparatuses in image forming devices face risks of thermal damage due to delayed actuation of safety elements, especially when the heating element's temperature rises abruptly during rotation stoppages, leading to potential overheating and damage before the safety element can intervene.
Innovation Solution
The apparatus incorporates a dual heating element system with a control unit and safety element connected in series, where a rotation detection circuit limits the drive of the second heating element when it detects a rotation stoppage, and a power supply control circuit manages the heating elements to maintain a set temperature and de-energize them upon abnormal temperature rise, thereby preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety element is used to suppress overheat, then the apparatus can protect against thermal damage, but the actuation of the safety element delays when large power is supplied to the heating element in rotation stop state
Solution Approach 1:
The rotation detection sensor detects the rotation state of the pressing member in advance, and the control unit proactively adjusts or stops power supply to the heating element before abnormal temperature rise occurs, preventing the need for delayed safety element actuation
Solution Approach 2:
The system uses feedback from the rotation detection sensor to continuously monitor the pressing member's rotation state and dynamically adjusts heating element power supply accordingly, enabling real-time response to rotation stoppages
2Ease of operation
If the control unit fails, then the energization amount to the coil cannot be limited, but the apparatus may still suffer thermal damage before the safety element is actuated
Solution Approach 1:
The rotation detection sensor acts as an intermediary that provides direct feedback about the pressing member's rotation state to the control unit, enabling the control unit to make informed decisions about power supply adjustment even in critical situations
Solution Approach 2:
The system performs preliminary detection of rotation state and proactive power adjustment before thermal damage can occur, ensuring protection even if the control unit experiences failures or delays
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
This solution effectively reduces the risk of thermal damage by actuating the safety element before significant overheating occurs, ensuring the apparatus operates safely and prevents damage during energization runaway or rotation stoppages.
Implementation Method 1
a heating element serving as a heat source, a power supply that supplies a current to the heating element
Implementation Method 2
a safety element device provided in the fixing apparatus suppresses overheat in the event of energization runaway
Data Source
AI summary
A fixing apparatus that conveys a printing medium to a fixing nip portion formed by rotating members, and fixes an image onto the printing medium by heat from heating elements. The fixing apparatus also includes a safety element, a rotation detection circuit, and a limiting circuit. The safety element is in a power supply path to supply electrical power to the heating elements and to shut off the path in response with an abnormal temperature. The rotation detection circuit detects a rotation state of the rotating members. The limiting circuit limits a drive of a second driving circuit per a rotation detection circuit output. A first driving circuit detects that the circuit drives a first heating element per a control signal, regardless of the rotating members rotation state, and the second driving circuit drives a second heating element per a control signal and the output from the rotation detection circuit.