Fixing Device Heat Roller Temperature Control
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Solution Overview
Problem
The existing temperature controlling method for fixing devices in image forming apparatuses leads to 'undershoot' where the temperature between the heat roller and back-up roller drops significantly when the recording sheet enters, causing heat loss and potentially inadequate thermal fixation of images.
Innovation Solution
An image forming apparatus with a fixing device that includes a heat source, a temperature sensor, and a controller. The controller determines a supplemental output to maintain heat until the recording sheet reaches the nip region by switching from a first target temperature to a second, lower target temperature and increasing the heat source's output if the sheet is detected approaching, ensuring consistent heat application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat source output is gradually reduced to control the heat roller temperature, then the temperature control is achieved, but the temperature drops significantly when the recording sheet enters causing undershoot
Solution Approach 1:
The controller determines in advance whether a recording sheet will enter the fixing device by checking the conveyance state. When a sheet is detected to be approaching, the controller sets a supplemental output that is higher than the normal calculated output, preparing extra heat before the sheet actually enters. This preliminary action prevents the temperature from dropping when the sheet absorbs heat, thereby eliminating undershoot while maintaining gradual temperature reduction for energy saving.
2Use of energy by stationary object
If the heat source output is reduced to save energy during stand-by period, then energy consumption is reduced, but the temperature may not be sufficient when a sheet enters
Solution Approach 1:
During the stand-by period, the controller gradually reduces the heat source output to save energy. However, when a recording sheet is detected to be approaching the fixing device, the controller immediately switches to a supplemental output mode that provides higher heat. This preliminary detection and response ensures that sufficient temperature is maintained for thermal fixation while minimizing energy consumption during periods when no sheets are present.
Solution Approach 2:
The controller continuously monitors the temperature of the heat roller via a temperature sensor and adjusts the heat source output accordingly. The controller calculates the difference between the target temperature and actual temperature, and modifies the heat output based on this feedback. This feedback mechanism ensures that the temperature remains within the required range while optimizing energy usage.
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 suppresses the occurrence of undershoot, maintaining adequate heat for thermal fixation of images by ensuring a consistent and sufficient heat supply during the image forming process.
Implementation Method 1
a heat source configured to generate an amount of heat
Implementation Method 2
a temperature sensor configured to detect a temperature of the heat member
Implementation Method 3
a fixing device configured to thermally fix the image on the recording sheet
Data Source
AI summary
An image forming apparatus includes a fixing device, a temperature sensor and a controller. The fixing device includes a heat source, a heat member heated by the heat source, and a back-up member. The temperature sensor detects a temperature of the heat member. The controller controls the heat source and includes an output determination unit determining an output at which the heat source is operated to generate a target temperature; a first setting unit setting a first target temperature; a second setting unit setting a second target temperature lower than the first target temperature; a switching unit switching the target temperature from the first target temperature to the second target temperature; a determination unit determining whether a recording sheet is conveyed; and a supplemental output control unit generating a supplemental output greater than the output if the recording sheet is conveyed when the target temperature is switched.