Paper Sensor Placement for Fuser Moisture Protection
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Solution Overview
Problem
The performance of paper sensing units in image forming apparatuses deteriorates due to moisture condensation on sensors caused by high-temperature heat from the fusing unit, leading to inaccurate light emission and reception.
Innovation Solution
An image forming apparatus with a paper sensor positioned between the fan and the conveyance path, where the light sensing area is open towards the fan, preventing direct airflow and water vapor from reaching the sensor, and a lever system to block light selectively, ensuring effective sensing despite high-temperature and humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the paper sensor is arranged on the conveyance path to sense paper passing through the fuser, then paper sensing function is achieved, but moisture condenses on the sensor surface causing performance deterioration
Solution Approach 1:
The patent introduces an air flow path as an intermediary element between the high-temperature zone and the sensor. This air flow path directs cool air from the front surface toward the rear surface, creating a protective airflow that prevents moisture-laden hot air from contacting the sensor directly, thereby resolving the condensation problem while maintaining sensor functionality
Solution Approach 2:
The patent extracts the sensor from the direct high-temperature and high-humidity environment by positioning it in a zone influenced by the cool air flow. The sensor is placed such that it can detect paper passage through vibration transmission from the conveyance path while being protected from the harmful thermal and moisture conditions by the directed air flow
2Temperature
If the fan is positioned to discharge high-temperature air efficiently, then heat dissipation is improved, but water vapor flows directly onto the sensor causing condensation
Solution Approach 1:
The patent applies local quality by creating different air flow conditions in different zones. The front surface allows hot air intake for efficient heat dissipation, while the rear surface receives directed cool air flow that protects the sensor area. This localized quality differentiation enables simultaneous heat dissipation and sensor protection
Solution Approach 2:
Instead of protecting the sensor by blocking the fan or reducing its effectiveness, the patent inverts the approach by using the fan's exhaust flow pattern to create a protective cool air current that flows toward the sensor area. The harmful hot air flow is inverted into a beneficial protective flow by strategic positioning and timing
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 paper sensing performance by preventing moisture condensation on the sensor, maintaining accurate light detection and preventing sensor malfunction, while maintaining a compact structure.
Implementation Method 1
a light emitting portion and a light receiving portion that are arranged on the second surface to be spaced apart from each other and to face each other
Implementation Method 2
a lever configured to be moved by the paper passing through the conveyance path to selectively block light irradiated from the light emitting portion toward the light receiving portion
Implementation Method 3
a fan configured to discharge air from inside the main body to outside of the main body
Implementation Method 4
the moisture included in the paper and the peripheral portion thereof is evaporated by high-temperature heat that is applied to the paper through the fusing unit
Implementation Method 5
the evaporated moisture is condensed on peripheral components having a temperature that is relatively lower than that of the fusing unit
Data Source
AI summary
An image forming apparatus includes a main body, a fan configured to discharge air inside the main body out of the main body, and a paper sensor arranged between a conveyance path of a paper that has passed through a fusing unit and the fan to sense the paper passing through the fusing unit, wherein a light sensing area of the paper sensing unit is open toward the fan.