Heater Power Control for Fixing Nip Transition
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Solution Overview
Problem
Conventional image forming apparatuses with pressure changing mechanisms in fixing devices require longer warm-up times due to the risk of heater cracking when electricity is supplied before reaching the desired pressurization state, leading to increased first print out time (FPOT) and usability issues.
Innovation Solution
An image forming apparatus with a power control unit that starts heating the heater during the transition period from a pressure release state to a pressurization state, controlling the power supply to prevent the heater temperature from exceeding a predetermined upper limit, thereby preventing cracking and reducing warm-up time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If electricity is supplied to the heater before the pressurization state is attained, then the warm-up time is shortened, but the heater temperature rises abruptly causing cracking of the heater
Solution Approach 1:
The pressure changing mechanism is activated in advance to transition from the pressure release state to the pressurization state before electricity is supplied to the heater. This preliminary pressurization action prevents abrupt temperature rise and heater cracking while enabling earlier heater operation to shorten warm-up time
Solution Approach 2:
The control unit monitors the operational state of the pressure changing mechanism and uses this feedback information to determine the appropriate timing for supplying electricity to the heater. This feedback control ensures electricity is supplied only after pressurization is attained, preventing heater damage
2Reliability
If electricity supply to the heater is delayed until after the pressurization state is attained, then heater cracking is prevented, but the warm-up time and first print out time are longer
Solution Approach 1:
The pressure changing mechanism performs the pressurization action in advance before heater operation begins. This preliminary action enables the heater to start heating earlier without risking cracking, thus reducing the overall warm-up time and first print out time while maintaining heater reliability
3Stability of the object's composition
If the pressure changing mechanism operates to switch between pressurization and pressure release states, then setting of elastic members is prevented, but the device complexity increases
Solution Approach 1:
The pressure changing mechanism serves multiple functions: it prevents setting of elastic members during idle periods, enables earlier heater operation to shorten warm-up time, and provides a controlled transition state for safe heater operation. This multi-functionality justifies the added device complexity
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 a faster warm-up time while preventing heater damage, thereby reducing the FPOT and enhancing usability by controlling the power supply during the transition period.
Implementation Method 1
a heater having a heat generating resistor on a ceramic substrate
Data Source
AI summary
An image forming apparatus includes an image forming unit, a fixing unit, and a power control unit. The image forming unit forms an unfixed image on a recording material. The fixing unit includes an endless belt, a heater held in contact with the endless belt, a pressurization roller to form a fixing nip portion for pinching and conveying the recording material together with the heater via the endless belt, and a pressure changing mechanism to effect switching between a pressurization state and a pressure release state. The power control unit controls power to the heater. In response to transitioning from the pressure release state to the pressurization state, the power control unit starts power to the heater during a transition period before the pressurization state is attained and controls power to the heater such that a heater temperature does not exceed a predetermined upper limit temperature during the transition period.