Fixing Belt Grounding Detection to Prevent Electrostatic Offset

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Solution Overview

Problem

Static electricity accumulates on the fixing belt in belt type or on-demand type fixing devices due to repeated sliding contact, leading to electrostatic offset and image quality deterioration.

Innovation Solution

The fixing belt is electrically connected between a power source and a ground terminal, with a controller determining current flow and controlling the heater based on this connection, using an insulated detection element like a photocoupler to ensure stable grounding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the fixing belt is connected to ground terminal to discharge static electricity, then electrostatic offset is prevented, but the connection becomes unstable due to rotation of the fixing belt

Engineering Contradiction:
Improvegrounding connection stabilityVSAvoidelectrostatic offset
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an insulated detection element as an intermediary component between the fixing belt and the control system. This element detects the grounding connection status without creating a direct electrical path, allowing stable detection of whether the fixing belt is properly grounded while avoiding interference with the rotating belt's electrical characteristics.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback control mechanism where the controller continuously monitors the grounding connection status through the insulated detection element and adjusts the heater operation accordingly. When grounding is detected, the heater operates to prevent electrostatic accumulation; when grounding is absent, the heater is turned off, creating a closed-loop control system that adapts to the rotating belt's connection status.

Inventive Principle:
Principle #23Feedback

2Reliability

If the heater operates continuously to prevent electrostatic accumulation, then image quality is maintained, but energy is wasted when grounding is not present

Engineering Contradiction:
Improveimage quality stabilityVSAvoidheater energy consumption
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent uses feedback control where the controller monitors grounding status through the insulated detection element and adjusts heater operation accordingly. The heater only operates when grounding is detected, eliminating unnecessary energy consumption while maintaining image quality when needed.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the operational parameter of the heater from continuous operation to conditional operation based on grounding detection. The heater's on/off state is dynamically adjusted according to the grounding connection status, optimizing energy consumption while maintaining image quality stability when grounding is present.

Inventive Principle:
Principle #35Parameter changes

3Loss of energy

If the heater is controlled based on grounding detection, then energy efficiency is improved, but the system complexity increases due to detection elements and control logic

Engineering Contradiction:
Improveheater energy consumptionVSAvoidcontrol system complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent introduces an insulated detection element as an intermediary that simplifies the control system by providing a clear, stable signal about grounding status. This intermediate component handles the complexity of detecting the rotating belt's connection state, allowing the main controller to operate with simpler logic.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical/electrical contact-based grounding detection with an insulated detection method that uses optical or electrical field interaction. This substitution eliminates the need for direct physical contact with the rotating belt, simplifying the mechanical connection requirements while maintaining reliable detection capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Prevents electrostatic offset by ensuring the fixing belt is properly grounded, maintaining image quality and preventing unintended changes in heater-belt distance.

Implementation Method 1

the insulated detection element includes a photocoupler

Methodology Applied
Scientific EffectPhotocoupler effect:

Implementation Method 2

the insulated detection element includes a light emitting diode and a light receiving element

Methodology Applied
Scientific EffectLight emitting diode effect: Light Emitting Diode

Implementation Method 3

the light receiving element is connected between a second power source and a ground terminal, and the controller determines whether a current is flowing through the fixing belt by detecting a current flowing through the light receiving element

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 4

a controller configured to control the heater to heat the fixing belt

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3792698B1Image forming apparatus and heating control method
Publication Date: 2025.07.30 TOSHIBA TEC KK
  • EP3792698B1 patent drawingFigure 1
  • EP3792698B1 patent drawingFigure 2
  • EP3792698B1 patent drawingFigure 3

AI summary

An image processing apparatus includes a fixing unit including a heater and a fixing belt. The fixing belt is electrically connected between a first power source and a ground terminal. A controller is configured to control the heater to heat the fixing belt. The controller is further configured to determine whether a current is flowing through the fixing belt and, upon determining that a current is not flowing through the fixing belt, control the heater not to heat the fixing belt.