Heating Member Temperature Correction in Image-Forming Apparatus
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Solution Overview
Problem
Conventional image-forming apparatuses using non-contact temperature sensors struggle to accurately control fixing operations due to a significant difference between the actual temperature of the heating member and the detected ambient temperature, especially during the warm-up period, leading to potential overheating.
Innovation Solution
An image-forming apparatus with a control device that selects between multiple functions to correct the detected temperature, switching from a first function to a second function at a prescribed timing during print control to adjust the power supply to the heating member, ensuring precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single function is used to correct the detected temperature during the entire print control process, then the device complexity is reduced, but the temperature control precision deteriorates due to the significant difference between actual heating member temperature and detected ambient temperature during the warm-up period
Solution Approach 1:
The print control process is divided into two distinct segments: a first period (warm-up period) and a second period (steady-state period). During the first period, a first correction function is applied to account for the large temperature difference between the heating member and ambient environment. During the second period, a second correction function is applied when the temperature difference is smaller. This segmentation allows each function to be optimized for its specific operational phase, resolving the contradiction between device simplicity and temperature control precision.
Solution Approach 2:
The correction function dynamically changes based on the operational phase of the heating member. The control device switches between the first correction function and the second correction function depending on whether the heating member is in the warm-up phase or steady-state phase. This dynamic adaptation enables accurate temperature control throughout the entire operation cycle while maintaining manageable device complexity through a systematic switching mechanism.
2Device complexity
If the detected ambient temperature is used directly to control power supply to the heating member, then the control system is simplified, but the temperature control accuracy deteriorates causing the heating member temperature to rise too high during the warm-up period
Solution Approach 1:
A correction function acts as an intermediary between the detected ambient temperature and the actual heating member temperature. Instead of using the raw detected temperature directly for control decisions, the system applies the appropriate correction function (first or second) to calculate the actual heating member temperature. This intermediary processing step prevents direct control based on inaccurate ambient temperature readings, thereby maintaining temperature control accuracy while keeping the overall control system relatively simple.
Solution Approach 2:
The correction function is applied in advance to the detected temperature before the temperature control decision is made. During the warm-up period, the first correction function pre-adjusts the detected ambient temperature to predict the actual heating member temperature. This preliminary correction prevents the control system from reacting to inaccurate temperature data, avoiding overheating while maintaining a straightforward control architecture.
3Ease of operation
If a single correction function is applied throughout the print control process, then the ease of operation is improved, but the fixing operation control precision deteriorates
Solution Approach 1:
The temperature correction operation is segmented into two distinct phases with different correction functions. The first correction function is applied during the warm-up period when the heating member temperature is rapidly changing. The second correction function is applied during the steady-state period when the temperature is stable. This segmentation maintains ease of operation through automated phase detection and function switching, while achieving precise fixing operation control by using the appropriate correction function for each operational phase.
Solution Approach 2:
The correction operation dynamically adapts to the operational phase of the heating member. The control device automatically determines whether the heating member is in the warm-up phase or steady-state phase and switches between the first and second correction functions accordingly. This dynamic approach maintains operational simplicity through automated switching while achieving high precision in fixing operations by using the most appropriate correction function at each moment.
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 approach allows for precise control of fixing operations by approximating the actual temperature of the heating member, preventing overheating and ensuring accurate thermal fixing of toner images on recording sheets.
Implementation Method 1
a non-contact temperature sensor disposed in a position separate from the heating member and configured to detect temperature of the heating member
Data Source
AI summary
An image-forming apparatus includes: a fixing device; a power supply unit; a non-contact temperature sensor; and a control device. The fixing device has a heating member. The power supply unit is configured to supply electric power to the heating member. The non-contact temperature sensor is disposed in a position separate from the heating member and configured to detect temperature of the heating member. A first function and a second function respectively produce a first corrected temperature value and a second corrected temperature value smaller than the first corrected temperature value with respect to a given detected temperature. The control device is configured to: select the first function to correct the detected temperature at a start of a print control process; switch from the first function to the second function at a prescribed timing during the print control process; and control the power supply unit based on the corrected temperature.