AC High-Voltage Output Control for Image Forming Apparatus
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Solution Overview
Problem
Existing AC high-voltage devices in electro-photographic image forming apparatuses face issues with erroneous over-current detection due to conductive substances and momentary disturbances, leading to unsafe conditions and prolonged recovery times, as they are sensitive to conductive materials and prone to false alarms.
Innovation Solution
Implementing an intermittent output control mechanism in the AC high-voltage generating unit, which temporarily turns off the AC high-voltage output when an over-current is detected, then re-starts it after a short period, allowing for continued normal operation and preventing smoking or ignition, while extending the time for determining abnormality and reducing false detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the AC high-voltage device uses continuous monitoring with a fixed threshold to detect over-current, then safety is improved by quickly detecting abnormal conditions, but false detections increase due to sensitivity to conductive substances and momentary disturbances
Solution Approach 1:
The patent applies dynamics by making the detection threshold and monitoring duration adaptive rather than fixed. The control unit dynamically adjusts the determination threshold based on operational context and requires the over-current condition to persist for a predetermined time period before triggering protection. This dynamic approach allows the system to distinguish between transient disturbances and genuine over-current faults, reducing false detections while maintaining safety.
Solution Approach 2:
The patent implements preliminary action by establishing a predetermined time period duration before actually turning off the AC high-voltage output. When an over-current condition is detected, the system waits for the current to exceed the threshold for this predetermined period before activating the protection mechanism. This preliminary timing action prevents premature responses to momentary disturbances while ensuring rapid protection when genuine faults occur.
2Reliability
If the AC high-voltage output is immediately turned OFF when over-current is detected, then safety is improved by preventing smoking or ignition, but recovery time increases requiring power OFF/ON cycle
Solution Approach 1:
The patent applies feedback by continuously monitoring the AC high-voltage output current and using this feedback to control the output state. The control unit receives feedback about current levels and automatically adjusts the output accordingly - turning off when over-current persists beyond the predetermined period and automatically restarting when current returns to normal. This closed-loop feedback system eliminates the need for manual power cycling while maintaining safety.
Solution Approach 2:
The patent implements discarding and recovering by temporarily discarding (turning off) the AC high-voltage output when over-current is detected, then automatically recovering (restarting) the output once the abnormal condition clears. The control unit monitors the current state and automatically restores normal operation without requiring external intervention or power cycling, thus minimizing downtime while ensuring safety during abnormal conditions.
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 enhances safety by preventing smoking or ignition and reduces erroneous detections, allowing for longer normal operation and faster recovery from transient over-currents, ensuring reliable and safe operation of the image forming apparatus.
Implementation Method 1
an AC high-voltage transforming unit that transforms supplied power to AC high-voltage
Implementation Method 2
a static charge eliminator that eliminates static charge from the paper sheet through AC high-voltage discharge
Data Source
AI summary
An AC high-voltage device includes a voltage controlling unit that controls an AC transforming unit. The AC transforming unit transforms supplied power to an AC high voltage. The voltage controlling unit includes a constant-voltage controlling unit and an turn-off unit. The constant-voltage controlling unit controls the AC transforming unit when an over-current does not occur in the AC high voltage. The turn-off unit turns off the AC transforming unit during a period in which an over-correct occurs. The constant-voltage controlling unit re-starts the AC transforming unit after the period.