Rotatable Arm Sheet Sensor Preventing Jam Tearing
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Solution Overview
Problem
Conventional image forming apparatuses, such as laser beam printers, risk tearing and leaving jammed sheets inside when attempting to pull them out due to the sheet being caught by the sensor flag during jam clearance.
Innovation Solution
An image forming apparatus equipped with a rotatable arm portion and a stopper portion connected by a compression spring, allowing the arm to retreat from its detection position and preventing the jammed sheet from being torn by distributing the pulling force and ensuring the sheet is not left inside the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor flag is used to detect the presence or absence of sheets, then sheet detection function is improved, but sheet tearing occurs during jam clearance
Solution Approach 1:
The sensor flag is designed with rotatable arm portions that can dynamically change their position. During normal operation, the arm portions extend into the sheet feed cassette to detect sheets. During jam clearance, the arm portions can rotate to a retracted position, allowing jammed sheets to be pulled out without being caught by the sensor flag. This dynamic adaptability resolves the contradiction between maintaining detection function and preventing sheet tearing.
Solution Approach 2:
The sensor flag structure includes stopper portions that preliminarily determine the position of arm portions. Before jam clearance operation, the arm portions are positioned by the stoppers to avoid interfering with sheet removal. This preliminary positioning prevents the harmful effect of sheet tearing while preserving the detection capability for normal operation.
2Device complexity
If the sensor flag structure is simplified, then device complexity is reduced, but the ability to prevent sheet tearing during jam clearance is compromised
Solution Approach 1:
The sensor flag is segmented into multiple independent arm portions (first arm portion and second arm portion) connected by a compression spring. Each arm portion can independently rotate and retract during jam clearance. This segmentation allows the structure to remain relatively simple while achieving the reliability needed for safe jam clearance operation.
Solution Approach 2:
A compression spring acts as an intermediary element connecting the first and second arm portions. The spring allows the arm portions to move independently while maintaining their structural connection. This intermediary mechanism enables the sensor flag to achieve complex motion behavior with minimal additional components, resolving the contradiction between simplicity and reliability.
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
Enables safe and effective removal of jammed sheets without tearing, improving the usability and reliability of the image forming apparatus by preventing sheet breakage and ensuring complete removal.
Implementation Method 1
a rotatable arm portion (150a) and a stopper portion (150b) connected by a compression spring (150c)
Implementation Method 2
This sensor flag 150 is brought into contact with the sheet P by the gravitational force of the sensor flag 150
Data Source
AI summary
A detecting device for detecting the presence or absence of a sheet contained in a sheet containing portion includes a rotatable arm portion brought into contact with the sheet contained in the sheet containing portion, a stopper portion rotatable in association with the arm portion for determining the position of the arm portion when there is no sheet in the sheet containing portion and whose rotation is regulated when there is no sheet in the sheet containing portion. And when the sheet in a conveying path is to be pulled out, the arm portion is retreated from a position determined by the stopper portion due to the pressure of the sheet being pulled out.