Heat Roller Pulse Control Using Estimated Surface Temperature

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Solution Overview

Problem

The existing image forming apparatuses face challenges in preventing overshoot and temperature ripple due to the high cost of temperature sensors with good responsiveness, which are necessary for accurate temperature control in the fixing unit.

Innovation Solution

A temperature control device with a temperature estimation unit and a control signal generation unit is implemented, which estimates the temperature of the heat propagation target and generates conduction pulses to control the heater power based on both temperature estimation and detection results, allowing for effective temperature control without relying on highly responsive temperature sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a temperature sensor with good responsiveness is used to accurately detect heat roller surface temperature, then temperature control precision is improved, but the cost of the temperature sensor increases

Engineering Contradiction:

Improvetemperature detection precisionVSAvoidtemperature sensor cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent introduces an intermediary computational model that mediates between the inexpensive temperature sensor and the control system. This model estimates the actual heat roller surface temperature by compensating for the detection delay inherent in cost-effective sensors, thereby achieving accurate temperature control without requiring expensive high-responsiveness sensors

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the reliance on expensive physical sensor improvements with a computational/software-based solution. Instead of upgrading the physical temperature sensor to a more responsive (and expensive) model, the system uses algorithms to process the sensor data and estimate the true temperature, substituting mechanical/hardware enhancement with intelligent computation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If a temperature sensor with slow responsiveness is used to reduce cost, then temperature sensor cost is reduced, but temperature control precision deteriorates due to deviation between detected temperature and actual surface temperature

Engineering Contradiction:

Improvetemperature sensor costVSAvoidtemperature control precision

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the estimated temperature (derived from the inexpensive sensor reading through computational compensation) is fed back to the control system. This feedback loop allows the controller to adjust heating power based on the compensated temperature estimate, maintaining control precision despite using a low-cost sensor

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the parameter being controlled from the raw sensor temperature reading to a compensated estimated temperature. By transforming the temperature parameter through computational compensation that accounts for sensor responsiveness characteristics, the system achieves accurate temperature control using inexpensive sensors

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional temperature control is used without temperature estimation, then device complexity is reduced, but temperature control precision deteriorates due to overshoot and temperature ripple

Engineering Contradiction:

Improvecontrol system complexityVSAvoidtemperature control precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary action by estimating the temperature before using it for control decisions. The temperature estimation unit calculates the compensated temperature in advance, allowing the control system to proactively adjust heating power and prevent overshoot and temperature ripple before they occur

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The temperature estimation unit serves as an intermediary layer between the simple temperature sensor and the control system. This intermediary processes the raw sensor data to produce a compensated temperature estimate, adding computational sophistication without requiring complex hardware modifications

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution reduces the cost of temperature sensors and effectively prevents overshoot and temperature ripple by accurately controlling the surface temperature of the heat roller, improving the responsiveness of the temperature control system.

Implementation Method 1

heat propagation from a heater

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentUS11281134B2Temperature control device and image forming apparatus

Publication Date: 2022.03.22 TOSHIBA TEC KK

AI summary

A temperature control device controls a temperature of a temperature control target to which heat propagates from a heater by supplying power to the heater and includes a control circuit. The control circuit includes a temperature estimation unit and a control signal generation unit. The temperature estimation unit estimates the temperature of the temperature control target based on conduction to the heater. The control signal generation unit outputs a conduction pulse for controlling power to be supplied to the heater based on a temperature estimation result and a temperature detection result of the temperature control target by a temperature sensor.