Conveyor Speed Control via Encoder Anomaly Switching
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in controlling the conveying speed of a conveyer member, such as a transfer belt, due to encoder failures caused by dust, electrical contact issues, or other anomalies, leading to uncontrollable rotation speed and necessitating the shutdown of the drive motor and image forming apparatus to resolve the problem.
Innovation Solution
The implementation of a feedback control system that switches between Fb control and FG control based on the anomaly detection of the encoder signal, allowing continuous operation and accurate speed control of the conveyer member by using the Fb signal when normal and switching to FG control when anomalies occur, enabling automatic recovery to Fb control when the signal recovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If encoder-based feedback control is used to control the conveying speed of the transfer belt, then the rotation speed can be controlled accurately under normal conditions, but the system becomes unreliable when the encoder fails due to dust, electrical contact issues, or other anomalies
Solution Approach 1:
The system changes the control parameter from encoder-based feedback to frequency-based open-loop control when encoder anomalies are detected. The control unit monitors encoder signal quality and switches control modes based on signal validity, thereby maintaining reliability while preserving measurement precision when available
Solution Approach 2:
The control unit acts as an intermediary that monitors encoder signal quality and mediates between the encoder-based feedback control and frequency-based open-loop control. It detects encoder anomalies and switches control modes accordingly, preventing encoder failures from directly impacting system reliability
2Measurement precision
If the encoder fails and the system stops operation to resolve the issue, then measurement accuracy can be maintained, but productivity is reduced due to unnecessary shutdowns
Solution Approach 1:
The system dynamically adjusts control mode based on encoder signal quality rather than statically maintaining one mode. When encoder anomalies are detected, the system transitions from closed-loop feedback control to open-loop frequency control, and can switch back when encoder signals recover, thereby maintaining productivity while preserving measurement precision when available
Solution Approach 2:
The system ensures continuous operation by providing alternative control paths. When encoder-based control becomes unavailable, the frequency-based open-loop control maintains transfer belt operation, preventing shutdowns and ensuring continuous useful action while preserving the ability to return to precise feedback control when encoder signals recover
3Device complexity
If a single feedback control system is used to simplify the control structure, then device complexity is reduced, but the system lacks adaptability when encoder anomalies occur
Solution Approach 1:
The control unit performs multiple functions: it processes encoder feedback signals, monitors encoder signal quality for anomalies, determines signal validity, and controls motor drive based on either encoder feedback or frequency signals. This multi-functionality provides adaptability without significantly increasing device complexity
Solution Approach 2:
The control system is segmented into distinct functional blocks within the control unit: encoder signal processing, anomaly detection, validity determination, and motor control. This segmentation allows the system to maintain relatively simple overall structure while providing adaptability through modular functional separation
Data Source
Figure 1
Figure 2~3
Figure 4A
AI summary
A detecting unit (1) detects a conveying speed of a conveyer member (2). A driving unit (M) drives the conveyer member (2). A first control unit (420) performs a first feedback control of the conveying speed based on detected conveying speed and a predetermined target conveying speed. A second control unit (430) detects a rotation speed of the driving unit (M) and performs a second feedback control of the rotation speed based on detected rotation speed and a predetermined target rotation speed. A determining unit (340, 1240) determines whether the detecting unit (1) is anomalous based on the detected conveying speed while the first feedback control is performed. When determining unit (340, 1240) determines that the detecting unit (1) is anomalous, a switching unit (330, 630, 830, 835) that switches from the first feedback control to the second feedback control.