Heat Roller Temperature Control via Virtual Sensor Estimation
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Solution Overview
Problem
Existing image forming apparatuses face issues with temperature control in fixing devices due to time lags and poor responsiveness of temperature sensors, leading to overshoot and temperature ripples, which are costly to mitigate with highly responsive thermopile sensors.
Innovation Solution
A temperature control device comprising an input voltage estimation unit, a temperature estimation unit, and a control signal generation unit that estimates the temperature of a heat roller based on energization pulses and temperature measurements, allowing for precise control of the heater power supply to maintain target temperatures without expensive high-responsiveness sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor with good responsiveness (e.g., thermopile) is used, then temperature control precision is improved, but device cost increases
Solution Approach 1:
The patent creates a virtual copy of the temperature sensor's function through software estimation. The temperature estimation unit reconstructs the temperature waveform by estimating input voltage and integrating heating effects, producing a temperature value that mirrors what a high-responsiveness sensor would measure, without using the expensive physical sensor
Solution Approach 2:
The patent replaces the physical temperature sensing mechanism (thermopile sensor) with an electrical calculation system. By measuring input voltage and current and computing thermal accumulation through integration, the system substitutes a costly mechanical/physical sensor with an electrical computation approach
2Ease of manufacture
If a temperature sensor with poor responsiveness is used, then device cost is reduced, but temperature control stability deteriorates due to overshoot and temperature ripple
Solution Approach 1:
The system performs preliminary estimation of the temperature waveform by calculating input voltage and integrating heating effects before the actual temperature change occurs. This predictive approach allows the control system to anticipate temperature changes and adjust heater power in advance, preventing overshoot and ripple
Solution Approach 2:
The patent implements a feedback mechanism where the estimated temperature waveform is continuously compared with target temperature, and the heater power is adjusted based on this comparison. The feedback loop uses the calculated temperature estimation to maintain stable temperature control without relying on delayed sensor measurements
3Device complexity
If temperature measurement is delayed, then simpler temperature sensors can be used, but control precision deteriorates due to time lag
Solution Approach 1:
The patent introduces an intermediary calculation process between the heater power input and temperature measurement. The temperature estimation unit acts as an intermediary that computes what the temperature should be based on energy input, bridging the gap between heater control and actual temperature without relying on delayed sensor feedback
Solution Approach 2:
The system performs preliminary calculation of temperature based on input voltage and heating time before actual temperature measurement is needed. By integrating the heating effect in advance, the system obtains accurate temperature estimation without waiting for slow sensor response
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 effectively prevents overshoot and temperature ripples by accurately estimating and controlling the heat roller temperature, reducing costs associated with high-performance sensors and improving temperature control stability.
Implementation Method 1
a fixing device that fixes a toner image on a print medium by applying heat and pressure to the print medium by the fixing device... a heating member (e.g., a lamp or IH heater)... controls the surface temperature of the heat roller to reach a target value by increasing or decreasing an energization amount to a heater
Implementation Method 2
The temperature sensor measures a temperature of a surface of the heat roller... a temperature sensor (for example, a thermopile)
Data Source
AI summary
A temperature control device controls a temperature of a temperature control target to which heat is propagated from a heater by supplying power to the heater. The temperature control device includes processing circuitry that acquires a temperature measurement result of the temperature control target from a temperature sensor. The processing circuitry estimates an input voltage being supplied to the heater based on an energization time of the heater and a change in the temperature of the temperature control target during the energization time. The processing circuitry generates a temperature estimation result by estimating the temperature of the temperature control target based on a previous energization pulse used to control energization of the heater and the input voltage. The processing circuitry outputs the energization pulse to control the power supplied to the heater based on the temperature estimation result and the temperature measurement result.