Image Forming Apparatus Door Sensor and Interlock Switch Failure Detection
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Solution Overview
Problem
Image forming apparatuses face difficulties in determining and isolating failures between the interlock device and the opening/closing detection device, leading to delayed restoration and maintenance due to lack of power supply and incorrect notifications.
Innovation Solution
An image forming apparatus with a sensor to detect the door's open/closed state and an interlock switch to interrupt voltage, along with a controller to determine failures by analyzing changes in detection results and voltage states, allowing for identification of the faulty sensor or interlock switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interlock device is failed under a state in which the power to the load is interrupted, then the image forming apparatus cannot operate normally, but the image forming apparatus cannot notify the user of the occurrence of the abnormality because no power is supplied therein
Solution Approach 1:
The controller performs preliminary detection of the interlock device's operational state before power interruption occurs. By monitoring whether the interlock device has previously interrupted power supply, the system can identify failures before complete power loss, enabling early notification to users and prevention of total operational failure.
2Reliability
If the sensor or interlock switch is failed, then the image forming apparatus stops to operate normally, but the determination of the failure location is difficult
Solution Approach 1:
The controller continuously monitors the operational states of both the sensor and interlock switch, comparing their responses against each other and against expected behavior. This feedback mechanism enables the system to identify inconsistencies that indicate failure, allowing precise determination of which component has failed based on their relative operational states.
Solution Approach 2:
The failure detection system is segmented into independent monitoring of the sensor and interlock switch, with the controller analyzing their individual and relative states. By separating the detection functions and analyzing them independently then comparatively, the system can precisely identify which specific component has failed without requiring complex diagnostic procedures.
3Loss of information
If the opening/closing detection device is failed to erroneously detect the opening of the door, then the notification of the opening of the door is given, but the serviceman cannot immediately determine which of the interlock device and the opening/closing detection device is failed
Solution Approach 1:
The controller compares the notification signal from the sensor with the actual operational state inferred from the interlock switch and door position. When a discrepancy is detected—such as the sensor indicating door opening while the interlock switch and door position indicate closed state—the system identifies this as a sensor failure and provides targeted information to reduce diagnostic time.
Data Source
AI summary
An image forming apparatus includes: an image forming unit configured to form an image; a transfer circuit configured to generate a transfer voltage, and supply the transfer voltage to transfer roller for transferring the image onto a sheet; a door provided to a mounting portion onto which the image forming unit is mounted; a sensor configured to detect an open/closed state of the door; an interlock switch configured to interrupt voltage to be supplied to the transfer circuit, in a case where the sensor detects an open state in which the door is opened; and a controller configured to: determine whether a failure has occurred or not based on a detection result of the sensor and a supplying/interrupting state of the voltage of the interlock switch; and determine, in a case where determining that the failure has occurred, which of the sensor and the interlock switch is failed.