Image Forming Apparatus Fan Speed Control for Condensation Prevention
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Solution Overview
Problem
The image forming apparatus faces challenges with moisture condensation on the photosensitive drum due to increased relative humidity inside the housing, which affects the reliability of temperature detection by the thermistor and proper fan control, especially when the fan is not initially operating.
Innovation Solution
The apparatus employs a dual-sensor system with a first sensor outside the fan's airflow path to measure ambient temperature and a second sensor closer to the photosensitive drum to estimate the drum's temperature, allowing for controlled fan operation regardless of fan ability, and adjusts fan speed based on humidity and temperature readings to prevent condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fan is not operated to maintain lower temperature inside the housing, then energy consumption is reduced, but moisture condensation occurs on the photosensitive drum due to increased relative humidity
Solution Approach 1:
The system performs preliminary heating of the housing using the heater before printing operations begin. This raises the internal temperature above ambient temperature, creating a temperature differential that prevents moisture condensation on the photosensitive drum even when the fan remains inactive during printing, thus avoiding both energy waste and condensation issues
Solution Approach 2:
The heater acts as an intermediary element that mediates between the ambient environment and the internal housing environment. By actively heating the housing, it creates a controlled thermal environment that prevents moisture condensation without requiring continuous fan operation, thus resolving the contradiction between energy consumption and condensation prevention
2Object-affected harmful factors
If the fan is operated to prevent moisture condensation, then condensation on the photosensitive drum is reduced, but the thermistor detection accuracy deteriorates due to variable airflow affecting the sensor
Solution Approach 1:
The heater serves as an intermediary that creates a stable thermal environment inside the housing. By maintaining the internal temperature above ambient temperature, it eliminates the need for continuous fan operation, thereby preventing both condensation and airflow-induced thermistor detection errors simultaneously
Solution Approach 2:
The system performs preliminary heating before printing operations. This advance action establishes a stable thermal condition that prevents condensation without requiring active fan control during printing, thus ensuring accurate thermistor readings while preventing moisture condensation
3Productivity
If continuous printing is performed without fan operation to save energy, then productivity is improved, but relative humidity inside the housing increases excessively due to water vapor from heated sheets
Solution Approach 1:
The heater performs preliminary heating of the housing before printing operations. This creates a temperature buffer that allows continuous printing without fan operation while preventing excessive humidity buildup, as the pre-heated environment resists moisture condensation even when water vapor is generated during continuous printing
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 prevents moisture condensation on the photosensitive drum and ensures reliable fan control, maintaining optimal humidity levels and improving the accuracy of temperature detection, thereby enhancing the printing process.
Implementation Method 1
The temperature inside the housing may be detected by a thermistor
Implementation Method 2
The fuser may thermally fix a developing agent on a sheet with the heat from the heater. The heater may increase temperature inside the housing
Implementation Method 3
a fan to discharge air in the housing outward from the housing... the fan may be operated to restrain the temperature from rising excessively
Implementation Method 4
When the temperature inside the housing is lower than an atmosphere temperature outside the housing, moisture entering the housing may condense on a surface of the photosensitive drum
Implementation Method 5
as a sheet is heated by the fuser, moisture contained in the sheet may be vaporized to generate water vapor
Data Source
AI summary
An image forming apparatus, having a main body housing including an air outlet opening, a photosensitive drum, a fuser to thermally fix toner transferred from the photosensitive drum to a sheet on the sheet, a fan to generate an airflow toward the air outlet opening, and a controller, is provided. The controller is configured to, in a continuous stage of printing continuous from a beginning stage, count a cumulative printed page number being a cumulative number of pages printed by the image forming apparatus, in a case where the cumulative printed page number is smaller than a first page number, control the fan to rotate at a first speed, and in a case where the cumulative printed page number is equal to or larger than the first page number, control the fan to rotate at a second speed, the second speed being higher than the first speed.