Fixing Device Temperature Control for Image Uniformity
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Solution Overview
Problem
Conventional image forming apparatuses face issues with temperature unevenness in the fixing roller due to a drop in the pressing roller's temperature, leading to uneven fixability on sheets, which existing technologies have not adequately addressed.
Innovation Solution
A fixing device with a rotatable fixing member, a pressing member, a heat source, and temperature detection units that control the heat source based on temperature information from both the fixing and pressing members to maintain a consistent temperature, ensuring even fixability by synchronizing heat application with the sheet's passage through the nip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the pressing roller temperature is reduced to shorten warm-up time, then the warm-up time is shortened, but the fixing roller temperature becomes uneven in the circumferential direction
Solution Approach 1:
The system performs preliminary heating of the pressing roller before sheet feeding starts, and maintains its temperature through continuous low-power heating during the idle period. This preliminary action ensures that when sheets begin to pass through, both rollers are already at appropriate temperatures, preventing the temperature drop that causes circumferential unevenness in the fixing roller.
Solution Approach 2:
Temperature sensors continuously monitor the temperatures of both the fixing roller and pressing roller. The control unit adjusts the heating power of both rollers based on real-time temperature feedback, ensuring that the pressing roller temperature is maintained at an appropriate level to prevent temperature drops that would cause uneven heating in the fixing roller during continuous sheet feeding.
2Loss of energy
If the pressing roller temperature drops during continuous sheet feeding, then energy consumption is reduced, but temperature unevenness in the fixing roller increases
Solution Approach 1:
The system performs preliminary heating of the pressing roller before sheet feeding starts, and maintains its temperature through continuous low-power heating during the idle period. This preliminary action ensures that when sheets begin to pass through, both rollers are already at appropriate temperatures, preventing the temperature drop that causes circumferential unevenness in the fixing roller.
Solution Approach 2:
Temperature sensors continuously monitor the temperatures of both the fixing roller and pressing roller. The control unit adjusts the heating power of both rollers based on real-time temperature feedback, ensuring that the pressing roller temperature is maintained at an appropriate level to prevent temperature drops that would cause uneven heating in the fixing roller during continuous sheet feeding.
3Loss of time
If the diameter and thickness of the fixing roller are reduced, then warm-up time is shortened, but temperature fluctuation increases due to pressing roller temperature drop
Solution Approach 1:
The system performs preliminary heating of the pressing roller before sheet feeding starts, and maintains its temperature through continuous low-power heating during the idle period. This preliminary action ensures that when sheets begin to pass through, both rollers are already at appropriate temperatures, preventing the temperature drop that causes circumferential unevenness in the fixing roller.
Solution Approach 2:
Temperature sensors continuously monitor the temperatures of both the fixing roller and pressing roller. The control unit adjusts the heating power of both rollers based on real-time temperature feedback, ensuring that the pressing roller temperature is maintained at an appropriate level to prevent temperature drops that would cause uneven heating in the fixing roller during continuous sheet feeding.
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 temperature fluctuations in the fixing belt, maintaining a consistent temperature within a 3°C range, thereby ensuring even fixability and enhancing image quality while reducing energy consumption.
Implementation Method 1
a heat source configured to heat the fixing member
Implementation Method 2
a first temperature detecting unit configured to detect a temperature of the fixing member; a second temperature detecting unit configured to detect a temperature of the pressing member
Implementation Method 3
a fixing member configured to heat a recording medium carrying a yet-to-be-fixed image thereon
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A fixing device (22) sets a control period and a gap between recording media so that T1 + T2 = C x N is satisfied, where T1 denotes a time from when the leading end of a recording medium reaches a nip to when the trailing end thereof passes through the nip, T2 denotes a time corresponding to the gap between the recording media, C denotes the control period, and N denotes a positive integer; and heat generated by a heat source (5) is supplied to the recording medium in synchronization with a timing at which the recording medium enters the nip. A correction amount is added to an electrification time in each control period and reduced at a predetermined rate in each control period based on temperature information of a pressing member (2) before start of feeding. The correction amount is changed depending on the basis weight of the recording medium.