Low Melting Point Toner Fixing Device Standby Temperature Control
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Solution Overview
Problem
Low melting point toner used in image forming processes tends to harden and stick to the thermistor in the fixing device, causing scratches and image degradation due to prolonged exposure to high temperatures, leading to irreversible changes in toner viscosity and attachment issues.
Innovation Solution
Maintaining the temperature of the fixing device during standby at a range lower than the fixing temperature, specifically between -10°C to -60°C, to reduce thermal influence on the toner and prevent hardening, and using a temperature control unit to manage the heat roller's temperature effectively, ensuring the toner's viscosity remains suitable for image formation without causing scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low melting point toner is used to fix images at lower temperatures, then energy consumption is reduced and fixing speed is improved, but the toner hardens and sticks to the thermistor during standby, causing scratches on the heat roller
Solution Approach 1:
The patent applies preliminary action by maintaining the heat roller at a standby temperature (higher than ambient but lower than fixing temperature) before actual image forming occurs. This preliminary temperature maintenance prevents the toner from hardening and sticking to the thermistor during standby, while still allowing the system to consume less energy compared to maintaining full fixing temperature continuously. When image forming is needed, the temperature is quickly adjusted to the required fixing temperature.
2Manufacturing precision
If the heat roller temperature is maintained at fixing temperature during standby, then image quality is ensured upon wake-up, but the toner undergoes irreversible viscosity changes and attaches permanently to the thermistor
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the heat roller temperature based on the operational state. During standby, the temperature is maintained at a lower standby temperature (e.g., 50-100°C) rather than the full fixing temperature (e.g., 160-200°C). When image forming is detected, the temperature is increased to the fixing temperature range. This parameter change prevents toner hardening during standby while ensuring adequate temperature for quality fixing when needed, thereby eliminating the harmful effects of permanent toner attachment.
3Measurement precision
If the thermistor contacts the heat roller for temperature measurement, then temperature control is achieved, but the toner attached to the thermistor hardens and cannot be detached
Solution Approach 1:
The patent applies preliminary action by controlling the heat roller temperature to be at standby temperature (not full fixing temperature) during periods when no image forming is detected. This preliminary temperature control prevents toner from hardening on the thermistor surface during standby. When image forming is needed, the temperature is quickly raised to fixing temperature, ensuring proper image fixation while the previously prevented hardening allows easy toner detachment from the thermistor.
4Object-affected harmful factors
If standby temperature is reduced to prevent toner hardening, then scratches are prevented, but the warming-up time to reach fixing temperature increases
Solution Approach 1:
The patent applies dynamics by making the heat roller temperature adjustable and dynamic rather than fixed. The system has two distinct temperature states: a lower standby temperature for preventing toner hardening during idle periods, and a higher fixing temperature for actual image forming. The temperature can be dynamically switched between these states based on whether image forming is detected. This dynamic temperature control prevents scratches during standby while enabling quick temperature adjustment when needed, reducing the effective warming-up time from a cold start.
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 reduces the formation of scratches on the heat roller and minimizes image degradation by controlling the toner's viscosity and thermal exposure, allowing for improved image quality and extended device lifespan.
Implementation Method 1
low melting point toner, i.e., toner having a melting point temperature that is lower than that of a conventional toner, containing crystalline polyester has a feature of quickly melting with heat
Implementation Method 2
The thermistor contacts a heat roller of the fixing device to measure temperature
Implementation Method 3
the conventional toner attached to the thermistor is heated again and softened when subsequent fixing is performed
Data Source
AI summary
A method for forming a fixed toner image includes maintaining a fixing device temperature at a standby temperature, and after wake-up from the standby state, forming an unfixed toner image on a sheet using a low melting point toner. The difference between temperatures that cause a viscosity of the toner in first and second conditions to be 1.0 (105 Pa·s) is within a range of 30° C. to 60° C., the toner in the first condition not having been maintained in a 160° C. environment for 24 hours and the toner in the second condition having been maintained in a 160° C. environment for 24 hours. The method further comprises increasing the fixing device temperature to a fixing temperature of the toner, which is higher than the standby temperature, and after the fixing device temperature has reached the fixing temperature, passing the sheet with the unfixed toner image through the fixing device.