Image Forming Apparatus Heat Control via AC to DC Conversion
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Solution Overview
Problem
Existing image forming apparatuses, such as copiers and printers, face challenges with large power consumption and increased size due to the need for expensive insulating materials and complex circuit configurations when using halogen or ceramic heaters for fixing toner images, particularly when temperature detection and control systems are integrated.
Innovation Solution
The apparatus incorporates a voltage generation unit to convert AC voltage to DC, with separate control units for managing the heat generation and switch operations, allowing for efficient heat control and reduced complexity by ensuring insulation between primary and secondary circuit sides, thereby reducing costs and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heater is connected to AC power supply through switching control element with temperature detecting element in primary side, then the heater can be controlled to reach target temperature, but the distance between heater and control circuit needs to be sufficiently secured requiring expensive insulating materials and components
Solution Approach 1:
A photocoupler is introduced as an intermediary component between the primary side (heater control) and secondary side (control circuit). The photocoupler transmits control signals optically, providing electrical isolation while maintaining control functionality. This eliminates the need for expensive insulating materials and components between the heater and control circuit, reducing device complexity and cost while maintaining reliable temperature control.
2Measurement precision
If temperature detecting element is provided in primary side, then temperature information can be detected near the heater, but the circuit configuration becomes complicated requiring PWM control with additional components such as comparator
Solution Approach 1:
The temperature detecting element is extracted from the primary side and relocated to the secondary side, where it can be connected directly to the control circuit without requiring complex isolation or additional control components. This extraction simplifies the circuit configuration by eliminating the need for PWM control and comparators on the primary side, while maintaining accurate temperature detection capability through the isolated connection.
3Device complexity
If AC power supply is directly used for driving heater without voltage conversion, then the power supply system is simple, but the distance between primary side elements and secondary side control circuit needs to be sufficiently secured
Solution Approach 1:
The photocoupler serves as an intermediary that enables safe signal transmission across the required distance between primary and secondary sides. By providing optical isolation, it allows the system to maintain simple AC power supply direct driving while satisfying safety requirements for adequate separation between high-voltage and low-voltage components.
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 configuration results in a more compact, cost-effective image forming apparatus with improved safety and efficient heat control, eliminating the need for expensive insulating materials and simplifying circuit configurations.
Implementation Method 1
a voltage generation unit (105, 124) converting the input AC voltage and generating a DC voltage
Implementation Method 2
a heat generation member (102) generating heat by supplying the AC voltage to the heat generation member (102)
Data Source
AI summary
The image forming apparatus includes a first control unit which controls a voltage generation unit that converts an AC voltage to generate a DC voltage, a heat generation member, and a switch which supplies or shuts off electric power to the heat generation member. The first control unit acquires information for controlling the switch, and controls the switch.