Movable Sensor Housing for Sheet Edge Detection
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately detecting the edge of sheets with varying thicknesses, leading to potential conveyance failures and decreased sensing accuracy due to fixed gap sizes in the sheet conveying passage.
Innovation Solution
A sensor unit with a movable lighting housing that adjusts the gap size of the sheet conveying passage, allowing thicker sheets to expand the gap and prevent conveyance resistance, while maintaining focus for thinner sheets by setting the focal position at the center of the initial gap size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed gap size is used in the sheet conveying passage, then the structure is simple and manufacturing is easy, but sheets with varying thicknesses cannot be accommodated, leading to conveyance failures and decreased sensing accuracy
Solution Approach 1:
The first housing is made movable in the direction perpendicular to the sheet conveying direction, transforming the fixed gap structure into a dynamic one. The gap size changes automatically based on sheet thickness, allowing the system to adapt to different sheet types without complex manual adjustment mechanisms
Solution Approach 2:
The gap size parameter is made variable rather than fixed. By allowing the first housing to move, the gap dimension automatically adjusts to accommodate sheets of different thicknesses, resolving the contradiction between structural simplicity and adaptability
2Adaptability or versatility
If the gap size is increased to accommodate thicker sheets, then conveyance of thick sheets is enabled, but sensing accuracy for thinner sheets decreases due to focus deviation
Solution Approach 1:
The movable first housing creates a dynamic gap adjustment mechanism. When a thick sheet is present, the housing moves to increase the gap; when a thin sheet is present, the housing returns to its original position maintaining the optimal gap for focus and sensing accuracy
Solution Approach 2:
The system performs preliminary adjustment of the gap size based on the incoming sheet thickness before the sheet reaches the sensing zone. This ensures that the optimal gap configuration is already in place for accurate edge detection
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
This solution ensures reliable edge detection and prevents conveyance failures by dynamically adjusting the gap size, maintaining high sensing accuracy for sheets of varying thicknesses and reducing the risk of image position deviation.
Implementation Method 1
an edge detection sensor which is arranged in one of the first and second housings and which detects the side edge, along the conveying direction, of the sheet passing through the sheet conveying passage. This image forming apparatus senses the position of an end part of a sheet in its width direction based on the difference in the intensity of the light received by the edge detection sensor according to presence or absence of the sheet.
Data Source
AI summary
A sensor unit includes a first housing constituting a first conveying face of a sheet conveying passage, a second housing constituting a second conveying face arranged opposite the first conveying face with a predetermined gap, an edge detection sensor detecting a side edge along the sheet conveying direction, and a gap adjuster supporting the first housing movably in a direction in which the size of the gap increases. When, with the first housing arranged at the first position, a sheet with a thickness greater than a reference value passes through the sheet conveying passage, the first housing moves in the direction in which the size of the gap increases as the sheet enters the sheet conveying passage, to allow the passage of the sheet.