Image Forming Apparatus Abnormality Detection Mask Period
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Solution Overview
Problem
Image forming apparatuses often experience erroneous abnormality detection due to increased output current from power supplies, which can be caused by environmental factors like temperature and humidity, leading to false short-circuit alarms.
Innovation Solution
Implementing a mask period for abnormality detection processing, where the detection is suspended until the photoconductor completes one rotation, preventing false alarms by masking the detection of overcurrents during transient changes in surface potential and transfer current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If abnormality detection is continuously performed to ensure reliable operation, then detection reliability is improved, but false abnormality detection occurs during normal transient current changes
Solution Approach 1:
The system performs preliminary action by setting a mask period in advance before abnormality detection is performed. When a voltage control signal is detected, the mask period is established beforehand to prevent false detection of the expected current increase that occurs during normal operation. This preliminary timing mask ensures that when abnormality detection occurs during this period, it is recognized as a normal transient state rather than a true abnormality.
2Measurement precision
If detection sensitivity is increased to detect all abnormalities, then detection capability is improved, but false alarms increase due to normal operational current variations
Solution Approach 1:
The system converts the harmful effect of normal current increases during operation into a beneficial masking mechanism. By detecting the voltage control signal that causes expected current increases, the system establishes a mask period that transforms what would be false alarms into recognized normal operational states. The current increase that would normally trigger false alarms is instead used to define the timing of the mask period.
3Reliability
If continuous monitoring is maintained to ensure safety, then operational safety is improved, but system complexity increases due to additional control mechanisms
Solution Approach 1:
The control unit performs multiple functions using a single mechanism. It both controls the power supply timing and performs abnormality detection, while also generating the mask period signal. This multi-functionality eliminates the need for separate complex control mechanisms while maintaining continuous monitoring and safety. The same circuitry that controls normal operation also manages the masking of expected current variations.
Data Source
AI summary
An image forming apparatus includes an image bearer; a first power supply configured to generate a first voltage applied to the image bearer according to a first voltage control signal; a second power supply configured to generate a second voltage, which has a polarity opposite to a polarity of the first voltage, applied to the image bearer according to a second voltage control signal; and circuitry. The circuitry is configured to generate the first voltage control signal and the second voltage control signal, detect an overcurrent in the image forming apparatus as an abnormality; and set a mask period for masking detection of the abnormality in response to an input of the second voltage control signal after an input of the first voltage control signal.