Heater Voltage Adaptation via Series Parallel Switching

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Solution Overview

Problem

Existing image forming apparatuses face challenges in detecting failures when switching between serial and parallel connection states of heat generating members across different commercial power supply voltages, leading to potential excessive power supply and insufficient safety circuit response.

Innovation Solution

Incorporating a current detection part in the power supply path after branching toward the heat generating members in the parallel connection state and a voltage detection part to detect voltages at both ends of the heat generating members in the serial connection state, allowing for the detection of failures and ensuring safe operation across varying power supply voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the maximum power that can be supplied to the heater increases when used in a 200V system, then the heating capability is improved, but harmonic currents and flickers become conspicuous and safety circuit response becomes insufficient

Engineering Contradiction:
Improveheater powerVSAvoidsafety circuit response
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The heater is divided into two separate heat generating members (first and second heat generating members) that can be independently controlled. This segmentation allows the total heater power to be distributed across multiple elements, enabling better control over power delivery and safety monitoring for each segment individually while maintaining total heating capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection state between the two heat generating members is dynamically switched between series and parallel configurations based on the detected commercial power supply voltage. This dynamic switching adapts the heater's resistance and power characteristics to match the operating voltage conditions, optimizing heating efficiency while maintaining safety circuit effectiveness across different voltage environments.

Inventive Principle:
Principle #15Dynamics

2Power

If individual heaters with different resistance values are used for 100V and 200V areas, then the heating performance is optimized for each voltage, but device complexity increases due to replacement requirements

Engineering Contradiction:
Improveheating performanceVSAvoidheater replacement
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

A single heater assembly containing both first and second heat generating members is designed to function universally across both 100V and 200V commercial power supply systems. The multi-functional design eliminates the need for region-specific heater replacements by incorporating voltage-adaptive switching capability within the same physical heater unit.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The heater's electrical parameters (resistance and power consumption) are changed by switching the connection state between series and parallel configurations rather than by physical replacement. This parameter adaptation allows the same heater hardware to optimize its performance for different voltage conditions without requiring different physical components.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the resistance value of the heater is switched using a relay, then the heater can operate in both 100V and 200V areas, but excess electric power may be supplied if the relay or detection part fails

Engineering Contradiction:
Improvevoltage compatibilityVSAvoidfailure detection
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

A power supply voltage detection part continuously monitors the commercial power supply voltage and provides feedback to a connection state switching part. This feedback mechanism ensures that the connection state (series or parallel) is automatically adjusted according to the detected voltage, preventing excessive power supply by maintaining proper correspondence between voltage conditions and heater resistance configuration.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The connection state switching part proactively switches the heater configuration in advance based on detected voltage conditions before excessive power can be supplied. This preliminary action prevents the harmful effect of mismatched voltage-resistance pairing by establishing the correct operational state before the failure condition can develop.

Inventive Principle:
Principle #10Preliminary action

4Power

If both heat generating members generate heat in parallel connection state, then the heating power is doubled for 100V operation, but the current flowing through each member increases

Engineering Contradiction:
Improvetotal heating powerVSAvoidcurrent stress
Core Design Contradiction:
PowerVSStress or pressure

Solution Approach 1:

The total current load is segmented and distributed across two separate heat generating members. In parallel connection, the total power is divided between the two members, reducing the current stress on each individual member compared to using a single high-power element, while still achieving the required total heating output.

Inventive Principle:
Principle #1Segmentation

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

Enables reliable detection of failures and ensures safe operation by limiting electric power to the heater, preventing overheating and improving the response speed of safety circuits, thus enhancing the apparatus's reliability and performance across different voltage environments.

Implementation Method 1

a first heat generating member H1 and a second heat generating member H2 which generate heat by electric power supplied from a commercial power supply

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2548083B1Image forming apparatus
Publication Date: 2018.06.27 CANON KK
  • EP2548083B1 patent drawingFigure 1
  • EP2548083B1 patent drawingFigure 2A
  • EP2548083B1 patent drawingFigure 2B

AI summary

The image forming apparatus can be used in areas having different power supply voltages, in which a failure of the apparatus can be detected so that reliability of the apparatus is improved. The apparatus includes a connection state switching part which switches connection of a first heat generating member and a second heat generating member, which generate heat by electric power supplied from a commercial power supply through a power supply path, between a serial connection state and a parallel connection state, and a current detection part which detects current flowing in the power supply path. The current detection part is disposed in the power supply path after branching toward the first heat generating member and the second heat generating member in the parallel connection state.