Sheet Path Switching Detection for False Jam Prevention
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Solution Overview
Problem
Conventional image forming apparatuses face issues with erroneous detection of switching mechanism failures, leading to unnecessary user intervention and reduced usability due to sheet jams when sheets are conveyed to incorrect paths.
Innovation Solution
An image forming apparatus with a detecting unit at the discharge opening, a controller, and a discriminating unit to determine abnormality by measuring the time between detection start and end within a predetermined period, preventing erroneous detection of switching mechanism failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conveying path switching mechanism is used to switch the conveying destination of sheets, then the image forming apparatus can convey sheets to multiple different paths (discharge opening, reversing path, etc.), but if the switching mechanism fails, sheets may be conveyed to the wrong path causing erroneous sheet jam detection
Solution Approach 1:
The patent implements feedback by using a sensor to detect whether a sheet has been conveyed to the discharge opening and by measuring the timing of sheet conveyance. The control unit compares the detected conveyance timing with the switching mechanism's state to determine whether a switching failure has occurred, providing continuous feedback to verify proper sheet routing
Solution Approach 2:
The patent replaces mechanical failure detection with an electronic detection system. Instead of relying on mechanical indicators or manual checking, the system uses electronic sensors to detect sheet position and timing, and the control unit processes this data to electronically determine switching mechanism status, substituting mechanical detection methods with electronic ones
2Reliability
If the image forming apparatus notifies users of sheet jams when sheets are conveyed to wrong paths, then potential switching mechanism failures can be detected, but this causes erroneous sheet jam notifications that reduce usability
Solution Approach 1:
The system provides feedback to the control unit about actual sheet conveyance timing and position. By comparing this feedback with the intended conveying path and switching mechanism state, the system can accurately determine whether a sheet jam actually occurred or whether the sheet was simply conveyed to a different path, enabling precise error notification
Solution Approach 2:
The patent applies partial detection by focusing specifically on detecting sheet conveyance to the discharge opening and measuring conveyance timing, rather than monitoring all possible conveying paths equally. This selective detection approach allows the system to identify switching failures without generating false alarms for normal variations in sheet handling
Data Source
AI summary
An image forming apparatus includes a first conveying portion provided with a discharge opening, a second conveying portion, a switching unit switched between a first state in which a recording medium is guided to the first conveying portion and a second state in which the recording medium is guided to the second conveying portion, a detecting unit provided in the discharge opening and for detecting the recording medium, a controller for controlling the switching unit, and a discriminating unit for discriminating that the switching unit is abnormal in a case where after the switching unit is controlled by the controller so as to be switched to the second state, a time from a start of detection of the recording medium by the detecting unit to an end of the detection is within a predetermined period.