Sheet Detecting Device Rotary Cam Flag Mechanism
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Solution Overview
Problem
The existing sheet detecting devices using a reciprocating flag are limited in increasing productivity due to the requirement for a longer sheet interval and increased distance needed for flag return, which restricts the ability to enhance sheet conveying speed and reduce the interval between sheets.
Innovation Solution
A sheet detecting device with a sensor flag member that includes a rotary cam and abutment surfaces, allowing for a shorter interval between sheets by ensuring the flag returns to the standby position quickly, enabling detection even at high conveying speeds and short intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet conveying speed is increased to improve productivity, then the number of image-formed sheets per unit time increases, but the required sheet interval increases due to the flag return time, which limits further speed increase
Solution Approach 1:
The patent replaces the mechanical spring-based flag return mechanism with an active driving mechanism (motor or actuator) that can control the flag's return motion. This substitution allows for faster and more reliable flag return, reducing the time loss and enabling higher sheet conveying speeds while maintaining detection accuracy.
Solution Approach 2:
The patent implements preliminary action by actively positioning the flag in the standby position before the sheet arrives, rather than passively waiting for the spring to return it after the sheet passes. This proactive approach ensures the flag is ready for the next detection cycle, reducing the effective sheet interval and improving productivity.
2Productivity
If the sheet interval is reduced to improve productivity, then more sheets can be conveyed per unit time, but the flag cannot return to the standby position in time, causing detection failure
Solution Approach 1:
The patent replaces the passive spring-based return mechanism with an active driving mechanism that can reliably return the flag to the standby position within a shorter time frame. This ensures that even when sheets are conveyed at reduced intervals, the flag is guaranteed to be in the correct position for detection, maintaining detection reliability while improving productivity.
Solution Approach 2:
The patent changes the temporal parameter of the flag return process by reducing the return time through active driving. This parameter change allows the system to operate with shorter sheet intervals without compromising detection reliability, as the flag can reset faster than the sheet conveyance cycle.
3Measurement precision
If the flag return distance is increased to improve detection accuracy, then the detection position is more precise, but the required sheet interval increases, limiting productivity
Solution Approach 1:
The patent replaces the mechanical spring-based return system with an active driving mechanism that can achieve the required detection precision without increasing the return distance. The active driver can position the flag accurately at the standby position regardless of the detection position, decoupling precision requirements from return distance and enabling shorter sheet intervals for improved productivity.
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
The device effectively reduces the sheet interval between sheets, allowing for increased productivity in image forming apparatuses by ensuring reliable detection of sheet positions, even at high speeds and short intervals, thus meeting user demands for improved productivity.
Implementation Method 1
a light-shielding member 225 which shields a light path from a light-emitting portion to a photo detector in the sensor 224
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
In a related-art sheet detecting device including a flag rotating while being in contact with the leading edge of a sheet, it is difficult to improve productivity related to sheet conveyance by increasing a sheet conveying speed or reducing the interval between sheets successively conveyed. A sheet detecting device includes a sensor flag member 23 that is pressed and rotated by the leading edge of a conveyed sheet. The sensor flag member 23 is on standby in a standby position where the leading edge of the conveyed sheet abuts an abutment surface of the sensor flag member 23. An optical sensor 24 detects the conveyed sheet on the basis of a posture of the sensor flag member 23 pressed by the leading edge of the conveyed sheet. The sensor flag member 23 is rotatable to a sheet passage posture where the sheet is allowed to pass. After the trailing edge of the conveyed sheet passes the sensor flag member 23, the sensor flag member 23 is rotated from the sheet passage posture in the same direction as a sheet conveying direction and is positioned in the standby position.