Fuser Overheating Control via Dual Voltage Comparison
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Solution Overview
Problem
Conventional image forming apparatuses fail to prevent overheating of the fuser roller due to damage to the A/D port of the microcomputer, leading to continuous heating and potential scorching or disconnection of the thermostat, causing inconvenience and damage.
Innovation Solution
An image forming apparatus with a temperature sensor, a first overheating prevention unit to compare detected voltage with a reference voltage and turn off the fuser when overheating occurs, and a second overheating prevention unit to compare the A/D port voltage with the detected voltage to prevent overheating even if the A/D port is damaged, ensuring safe operation by turning off the fuser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single overheating prevention unit (comparator) is used to control the fuser, then the control system is simple, but the system reliability deteriorates when the A/D port is damaged
Solution Approach 1:
The single overheating prevention unit is segmented into two independent units: a first comparator for normal temperature control and a second comparator for A/D port damage detection. Each comparator independently monitors different aspects of the system, so that if one fails or is bypassed due to A/D port damage, the other continues to provide protection against overheating.
Solution Approach 2:
The second comparator is configured in advance to detect voltage discrepancies that indicate A/D port damage. By preparing this backup detection mechanism beforehand, the system cushions against the potential failure mode where the A/D port becomes damaged and the first comparator can no longer function reliably.
2Adaptability or versatility
If the A/D port is damaged and outputs incorrect voltage, then the microcomputer may malfunction, but the existing single comparator system cannot detect this damage
Solution Approach 1:
The second comparator creates a feedback mechanism that continuously monitors the voltage output of the A/D port and compares it with the actual temperature sensor voltage. When the A/D port is damaged and outputs incorrect voltage, this feedback loop detects the discrepancy and triggers the overheating protection, allowing the system to adapt to the damaged state.
Solution Approach 2:
The second comparator acts as an intermediary between the A/D port and the overheating protection system. It mediates the detection of A/D port damage by comparing voltages and translating the electrical discrepancy into a protective action, making the system aware of the A/D port's operational status.
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
Effectively prevents overheating of the fuser roller, preventing scorching and disconnection of the thermostat, ensuring safe operation and user convenience by incorporating additional safety measures to manage voltage discrepancies caused by A/D port damage.
Implementation Method 1
a temperature sensor to sense temperature of the fuser
Implementation Method 2
A heat lamp is provided in the fuser roller at its internal center. The fuser is heated by heat radiated from the heat lamp.
Data Source
AI summary
An image forming apparatus to prevent overheating of a fuser. In the image forming apparatus, a first overheating prevention unit compares the voltage detected by a temperature sensor, which senses temperature of the fuser, with a reference voltage and turns off the fuser when it overheats. A controller receives the detected voltage through an A/D port and performs on/off control of the fuser to keep its temperature at a predetermined level. A second overheating prevention unit compares the detected voltage with the A/D port voltage and turns off the fuser when the detected voltage is different from the A/D port voltage. When the A/D port is damaged, the A/D port voltage increased by the damage activates the second overheating prevention unit to turn off the fuser. This prevents overheating of the fuser caused by malfunction of the A/D port, thereby preventing disconnection of the thermostat or scorch of the fuser.