Heater Connector Engaging Structure for Thermal Expansion
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Solution Overview
Problem
Conventional image forming apparatuses experience contact malfunctions due to shifting of the connection terminal relative to the electrode in the fixing heater, caused by thermal expansion or external impacts, leading to poor electrical connections.
Innovation Solution
A heater unit with a heating resistor member and electrode disposed on a board, featuring a connector with a connection terminal and engaging portions to securely attach and prevent shifting, ensuring stable electrical connections despite thermal changes or external influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the end portion of the board is simply inserted into the connector, then the device complexity is reduced, but the connection terminal may shift relative to the electrode causing poor contact
Solution Approach 1:
The patent introduces an intermediary engaging structure consisting of an engaging portion on the heater board and a corresponding engaging groove on the connector. This intermediary mechanism prevents direct shifting between the connector and heater board while maintaining a relatively simple overall structure. The engaging portion fits into the engaging groove to create a mechanical interlock that stabilizes the relative position of the connection terminal and electrode.
2Temperature
If the heater length changes due to thermal expansion, then the thermal performance is improved, but the connector position shifts relative to the electrode causing contact malfunction
Solution Approach 1:
The patent applies the dynamics principle by creating a flexible engagement system that can accommodate thermal expansion. The engaging portion and engaging groove are designed with sufficient clearance and flexibility to allow the heater board to expand thermally without causing the connector to shift relative to the electrode. The spring property of the connector further enhances this dynamic adaptation, maintaining constant contact pressure despite length changes.
3Reliability
If the connector is firmly fixed to prevent any shifting, then the connection reliability is improved, but the thermal expansion of the heater cannot be accommodated
Solution Approach 1:
The patent applies parameter changes by designing the engaging structure with specific dimensional parameters that allow controlled movement. The engaging portion and engaging groove are dimensioned to permit a certain range of movement corresponding to thermal expansion, while still preventing excessive shifting that would cause contact malfunction. The spring constant and engagement geometry are optimized to balance firm fixation with thermal adaptability.
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 contact malfunctions by maintaining stable electrical connections between the connection terminal and electrode, even with changes in the heater's length due to thermal expansion or external impacts, ensuring reliable operation of the image forming apparatus.
Implementation Method 1
a fixing heater for fixing a toner image transferred to a surface of a print medium. The fixing heater is formed in a heating resistor pattern disposed on a board
Implementation Method 2
even when the specific connector attaching position of the heater is shifted due to a change in an entire length of the heater caused by thermal expansion of the heater
Data Source
AI summary
A heater unit includes a heater in which a heating resistor member and an electrode electrically connected to the heating resistor member are disposed on a board; a connector having a connection terminal and attached to the heater at a specific connector attaching position thereof for electrically connecting the connection terminal to the electrode; a heater side engaging portion disposed on the heater; and a connector side engaging portion for engaging with the heater side engaging portion. The heater side engaging portion is provided for restricting the connector attached to the heater at the specific connector attaching position from shifting relative to the specific connector attaching position.