Fuser Grounding Structure to Prevent Temperature Sensor ESD Failure
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Solution Overview
Problem
Temperature sensors in a fixing device installed into a main housing of an image forming apparatus are susceptible to failure due to electrostatic discharge between the external connector and the main housing connector.
Innovation Solution
The fixing device includes a connecting frame made of metal that is electrically continuous with the intermediate circuit board's ground, allowing static electricity to be dissipated during installation, and a helical compression spring to stabilize electrical continuity between the circuit board and the connecting frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the external connector is connected to the main housing connector during installation, then electrical connectivity is established, but electrostatic discharge may occur causing temperature sensor failure
Solution Approach 1:
The patent applies preliminary action by providing a preliminary ground connection path through the connecting frame and ground terminal before the external connector is fully engaged with the main housing connector. This allows static electricity to be dissipated in advance, preventing electrostatic discharge damage to the temperature sensors when the connectors engage.
Solution Approach 2:
The patent uses an intermediary approach by introducing the connecting frame with a ground terminal as a mediator between the intermediate circuit board and the main housing ground. This intermediary structure provides a dedicated static electricity dissipation path that is independent of the external connector connection, thereby protecting the temperature sensors from electrostatic discharge.
2Reliability
If the intermediate circuit board is directly connected to the main housing ground, then grounding is achieved, but the connection may be unstable during installation
Solution Approach 1:
The patent applies preliminary action by establishing the ground connection through the connecting frame and ground terminal before the external connector engagement is complete. This ensures that the intermediate circuit board is grounded in advance, providing a stable reference potential and preventing electrostatic buildup during the installation process.
Solution Approach 2:
The patent applies dynamics by making the connecting frame movable relative to the main housing, allowing it to be pushed in during installation. The elastic element provides dynamic compensation for positioning variations, ensuring that the ground terminal maintains stable electrical contact with the main housing ground regardless of minor misalignments during assembly.
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 configuration effectively prevents failure of the temperature sensors by dissipating static electricity, ensuring reliable operation of the fixing device.
Implementation Method 1
Since the ground of the intermediate circuit board is electrically continuous with the connecting frame that is connected to the ground of the main housing, static electricity can be dissipated via the connecting frame if an electrostatic discharge occurs between the external connector and the main housing connector
Implementation Method 2
The helical compression spring establishes electrical continuity between the ground of the intermediate circuit board and the connecting frame
Data Source
AI summary
A fixing device is installable into a main housing of an image forming apparatus and includes a heating rotator, a pressure rotator, a first temperature sensor, a second temperature sensor, an external connector, an intermediate circuit board, a first side frame, a second side frame, and a connecting frame. The heating rotator includes a heater. The pressure rotator nips a sheet in combination with the heating rotator. The external connector is connectable to a main housing connector of the main housing. The intermediate circuit board is configured to relay signals from the first temperature sensor and the second temperature sensor to the external connector. The connecting frame connects the first side frame and the second side frame. The connecting frame is made of metal and is connected to a ground of the main housing. The ground of the intermediate circuit board is electrically continuous with the connecting frame.