Cover-Resilient Sheet Jam Detection With a Body-Mounted Photosensor
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Solution Overview
Problem
Existing sheet conveying devices in image forming apparatuses face challenges in accurately detecting sheet jams and maintaining positional accuracy of components, particularly when the cover is opened or deformed, which can lead to erroneous detections and potential damage to internal components.
Innovation Solution
The sheet conveying device incorporates a detector system with a photosensor and a feeler mechanism, where the feeler is movable relative to a guide and positioned by a positioner within the device body, ensuring accurate detection of sheet presence and preventing erroneous jam detection even with cover deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cover is opened to expose the sheet conveyance path for removing jams, then the ease of operation is improved, but the positional accuracy of the detector components deteriorates
Solution Approach 1:
A feeler member is introduced as an intermediary between the sheet conveyance path and the photosensor. The feeler transmits mechanical movement from the sheet to the photosensor, enabling accurate detection even when the cover is opened or deformed. This mediator isolates the photosensor from direct exposure to cover deformation while still capturing sheet position information.
Solution Approach 2:
The detection mechanism transitions from direct optical detection in the cover to mechanical-coupled optical detection in the body. By moving the photosensor to the body and using the feeler as a mechanical linkage, the system detects sheet position from a different spatial dimension that is immune to cover deformation.
2Device complexity
If the photosensor is placed in the cover for direct detection, then the device complexity is reduced, but the reliability of detection deteriorates due to cover deformation
Solution Approach 1:
The feeler acts as a mechanical intermediary that decouples the photosensor from the cover structure. It transmits the sheet's positional information to the photosensor without requiring the photosensor to be physically attached to or move with the cover, thereby maintaining detection reliability despite cover deformation.
Solution Approach 2:
The detector is segmented into two functionally independent parts: the feeler that contacts the sheet and transmits movement, and the photosensor that remains fixed in the body to detect the transmitted movement. This segmentation allows each component to perform its function optimally without being affected by cover deformation.
3Manufacturing precision
If the feeler is fixed rigidly to ensure positional accuracy, then the manufacturing precision is improved, but the adaptability to cover opening/closing deteriorates
Solution Approach 1:
The feeler is designed with rotational freedom at its pivot point, transforming it from a rigid fixed component to a dynamic articulated component. This allows the feeler to adapt its angle according to whether the cover is open or closed, while its pivot point remains fixed to the body, ensuring consistent positional reference for detection.
Solution Approach 2:
The feeler combines two functions: it serves as both a mechanical linkage that transmits sheet movement and as an adaptive component that adjusts to cover position. By merging these functions into a single articulated component, the system achieves both precision and adaptability.
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
Enhances the accuracy of sheet jam detection, reducing the likelihood of erroneous detections and minimizing damage to internal components, thereby improving the reliability and maintenance efficiency of the image forming apparatus.
Implementation Method 1
The photosensor has a detection region in which the detected portion entering the detection region is detected by the photosensor
Data Source
AI summary
A sheet conveying device includes a body, a first guide in the body, a cover, a second guide in the cover, a detector, and a positioner. The first and second guides form a conveyance path at a closed state of the cover. The detector detects a sheet in the conveyance path and includes a photosensor in the body and a feeler in the cover. The feeler includes a detected portion movable in conjunction with the sheet passing through the conveyance path and a contacted portion. The photosensor has a detection region in which the detected portion entering the detection region is detected. The positioner in the body contacts the contacted portion to position the detected portion in the detection region.