Transfer Sheet Length Detection Error Correction
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Solution Overview
Problem
Existing image forming apparatuses face challenges in achieving high image position accuracy due to errors in detecting the length and posture of transfer materials, particularly when conveying materials with inclined postures and varying conveyance speeds, leading to issues like oblique passing and skew, which affect the precision of image formation on both sides of the material.
Innovation Solution
The apparatus employs a configuration with multiple sensors arranged symmetrically along the conveyance path to detect the leading and trailing ends of the transfer material, correcting errors caused by posture changes and conveyance speed variations, and adjusts the image forming position based on calculated length information to ensure accurate alignment and positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensor is used to detect the transfer material, then the device complexity is low, but the measurement precision of length and posture is insufficient
Solution Approach 1:
The patent divides the detection function into multiple sensors arranged at different positions along the conveyance direction. Specifically, a first sensor detects the leading end and a second sensor detects the trailing end of the transfer material, allowing independent measurement of each end's position and enabling calculation of the material's length and posture.
Solution Approach 2:
The patent adds the conveyance direction dimension to the detection system. By arranging sensors not just across the width but also along the conveyance direction at different positions, the system gains the ability to measure length and posture parameters that cannot be obtained from single-point detection alone.
2Productivity
If the transfer material is conveyed at varying speeds, then the productivity is improved, but the measurement precision of image position accuracy deteriorates
Solution Approach 1:
The patent uses the detection signals from the sensors to feedback the actual length and posture of the transfer material to the control system. This feedback information is then used to correct the image formation timing and position, ensuring accurate image placement even when conveyance speed varies.
Solution Approach 2:
The system dynamically adjusts image formation parameters based on real-time detection of transfer material length and posture. The control unit modifies image formation timing and position correction values according to the actual conditions detected by the sensors, allowing the system to maintain precision under varying conveyance speeds.
3Ease of operation
If the transfer material has inclined posture, then the ease of operation is improved, but the measurement precision of image position accuracy deteriorates
Solution Approach 1:
The patent replaces mechanical posture correction mechanisms with an optical/detection-based system. Instead of mechanically forcing the material into a horizontal position, the system uses sensors to detect the actual inclined posture and calculates correction values to compensate for the inclination, thereby maintaining image position accuracy while allowing flexible material handling.
Data Source
AI summary
An image forming apparatus is configured so that a first detection position and a second detection position are set along the direction of conveying a transfer material between adjacent conveyance rollers. The image forming apparatus has four sensors, two of which are disposed in the first detection position at a predetermined interval, and the remaining two of which are disposed in a second detection position at a predetermined interval. An actual length of the transfer material can be detected with high accuracy by performing (1) cancellation of an error in detection caused by variation in a speed at which the transfer material is conveyed, (2) cancellation of an error in detection caused by a skew, and (3) cancellation of an error in detection caused by oblique passing.