Sheet Deflection Detection for Image Forming Conveyance Control
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Solution Overview
Problem
Existing image forming apparatuses face erroneous sheet detection due to low rigidity sheets failing to press detection flags or actuators, leading to a complex configuration and detection failures.
Innovation Solution
An image forming apparatus with a detection unit comprising a first and second pivoting member and a sensor to accurately detect sheet deflection, using a first and second pivoting member pivoted by the sheet, and a sensor to control conveyance speed based on detection results, reducing erroneous detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single flag or actuator is used for sheet detection, then the device complexity is reduced, but detection reliability deteriorates due to erroneous detections with low rigidity sheets
Solution Approach 1:
The detection unit is segmented into multiple functional components: a first pivoting member (flag) that contacts the sheet, a second pivoting member (actuator) that detects the flag's movement, and a sensor that detects the actuator's position. This segmentation allows each component to perform a specific function, improving detection reliability while maintaining relatively simple overall structure.
Solution Approach 2:
The first pivoting member acts as an intermediary between the sheet and the second pivoting member. Low rigidity sheets that cannot directly press the actuator can still trigger detection by pressing the flag, which then pivots and presses the actuator. This intermediary mechanism ensures reliable detection across different sheet types without increasing device complexity.
2Reliability
If multiple loop detecting sensors and actuators are provided to prevent erroneous detections, then detection reliability is improved, but device complexity increases
Solution Approach 1:
Instead of using multiple identical detection systems, the patent uses a copied mechanical advantage mechanism where the first pivoting member's movement is transferred to the second pivoting member. This allows a single sensor to effectively detect sheet presence with the reliability of multiple sensors, reducing device complexity while maintaining detection accuracy.
3Device complexity
If a simple flag mechanism is used, then device complexity is reduced, but measurement precision deteriorates due to inability to detect sheet deflection accurately
Solution Approach 1:
The detection mechanism transitions from direct linear displacement detection to angular displacement detection. The pivoting members convert the sheet's linear deflection into rotational movement, which is then detected by the sensor. This dimensional transformation improves measurement precision for sheet deflection while keeping the mechanical structure simple.
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
Accurate detection and control of sheet deflection in various types of sheets, minimizing image defects and creases by adjusting conveyance speed, thereby enhancing detection reliability and reducing complex configurations.
Implementation Method 1
a sensor configured to detect a pivotal movement of the second pivoting member
Data Source
AI summary
An image forming apparatus includes a transfer unit configured to transfer a toner image on the sheet, a fixing unit configured to fix the toner image transferred by the transfer unit to the sheet, a detection unit configured to detect the amount of deflection, and a control unit configured to control a speed of conveyance of the sheet based on a detection result from the detection unit, wherein the detection unit includes, a first pivoting member configured to be pivoted about a first pivot shaft in a first pivoting direction by the sheet pressing the first pivoting member, a second pivoting member configured to be pivoted about a second pivot shaft that is different from the first pivot shaft in a second pivoting direction by the first pivoting member pressing the second pivoting member, and a sensor configured to detect a pivotal movement of the second pivoting member.