Image Forming Sheet Bending Detection with Rotary Encoder Control
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Solution Overview
Problem
Existing image forming apparatuses struggle to accurately detect and control varying bending amounts (loop amounts) of different types of sheets, leading to issues like color shift, paper wrinkles, and image disturbances.
Innovation Solution
The apparatus includes a detection unit with a rotation portion and a rotary encoder to detect sheet bending, using pulse signals to control the fixing portion's conveyance speed based on the detected bending amount, allowing for precise adjustment of sheet conveyance speed to maintain optimal bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single loop detection sensor is used, then the device complexity is reduced, but the measurement precision of bending amounts for various sheet types deteriorates
Solution Approach 1:
The detection system is segmented into multiple independent loop detection sensors positioned at different locations. Each sensor detects bending amounts at its specific position, allowing the system to distinguish between different sheet types (thin paper, plain paper, thick paper) by comparing the bending patterns detected at each sensor location. This segmentation enables precise measurement of varying bending amounts without requiring a single complex sensor.
Solution Approach 2:
The invention adds a spatial dimension to the detection system by placing multiple sensors at different positions along the sheet path. Instead of relying on a single sensor to measure all bending variations, the system uses the spatial arrangement of multiple sensors to capture the distribution of bending amounts, thereby improving measurement precision while maintaining relatively simple device complexity.
2Measurement precision
If multiple loop detection sensors are added to detect various bending amounts, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Each loop detection sensor is designed with multi-functionality, serving both as a bending amount detector and as a reference point for sheet type identification. The sensors use similar detection mechanisms (photo-interrupters or mechanical flags) that can universally detect bending at their respective positions, reducing the need for specialized components while improving measurement precision across different sheet types.
Solution Approach 2:
The multiple loop detection sensors are pre-positioned at optimized locations where they can detect characteristic bending patterns for different sheet types. This preliminary arrangement of sensors allows the system to automatically identify sheet types and adjust control parameters without requiring complex real-time analysis, thereby improving measurement precision while keeping the device configuration manageable.
3Device complexity
If the sheet conveyance speed is not adjusted based on bending amount, then the control system is simpler, but harmful factors such as color shift and image disturbances increase
Solution Approach 1:
The control system implements feedback by continuously monitoring bending amounts detected by the loop detection sensors and automatically adjusting the sheet conveyance speed of the fixing portion accordingly. When bending amounts exceed predetermined thresholds, the system reduces conveyance speed to prevent image disturbances, color shift, and paper wrinkles. This feedback mechanism eliminates harmful factors while maintaining relatively simple control system configuration through rule-based adjustments.
Solution Approach 2:
The system dynamically changes the conveyance speed parameter of the fixing portion based on detected bending amounts. By adjusting this critical parameter in response to real-time bending measurements, the system prevents image quality defects without requiring complex control algorithms, thereby reducing harmful factors while keeping the control system configuration simple and manageable.
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 enables accurate detection and control of bending amounts for multiple sheet types, reducing color shift, paper wrinkles, and image disturbances, ensuring high-quality print output.
Implementation Method 1
a rotary encoder configured to output a pulse signal corresponding to a rotation amount of the rotation portion
Data Source
AI summary
An image forming apparatus includes a transfer portion, a fixing portion, a detection unit configured to detect a bending amount of the sheet nipped between the transfer portion and the fixing portion, and a control unit. The detection unit includes a rotation portion configured to rotate in a rotation direction from a standby position by being pressed by the sheet nipped by the transfer portion and the fixing portion, a rotary encoder configured to output a pulse signal corresponding to a rotation amount of the rotation portion, and a rotation detector configured to detect that the rotation portion has reached a detection position downstream of the standby position in the rotation direction. The control unit controls a sheet conveyance speed of the fixing portion based on the pulse signal output from the rotary encoder after the rotation detector detects that the rotation portion has reached the detection position.