Sewing Machine Fabric Movement Detection Using Spherical Encoder
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Solution Overview
Problem
Existing sewing machines face challenges in accurately adjusting thread tension due to discrepancies between estimated and actual fabric movement, leading to irregular thread tension and compromised stitch quality, especially in variable fabric movement conditions like free motion mode.
Innovation Solution
A sewing machine equipped with a spherical body that rotates with the fabric and encoders to detect its movement, allowing for precise calculation of actual fabric movement and controlled supply of the lower thread by separate motors, ensuring accurate thread tension adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lower thread feeder is lowered to adjust the supplying amount of the lower thread, then the thread tension can be adjusted, but the amount of lowering must be precisely controlled according to sewing conditions, increasing device complexity
Solution Approach 1:
The patent employs feedback control by detecting the actual fabric movement amount through the spherical body rotation detection unit and using this information to automatically adjust the lower thread feeder lowering amount. The detection unit provides real-time feedback on fabric movement, allowing the control unit to precisely control the thread feeder without manual intervention, thereby achieving accurate thread tension adjustment while reducing operational complexity
Solution Approach 2:
The patent replaces manual mechanical adjustment with an automated detection and control system. Instead of relying on mechanical linkages and manual operation to control thread tension, the system uses a spherical body with encoder detection to sense fabric movement and electronically controls the thread feeder, substituting complex mechanical control with sensor-based electronic control
2Ease of operation
If the cloth feed amount adjustment lever is used to estimate fabric movement, then the supplying amount can be adjusted, but the estimated amount differs from the actual amount due to fabric type and user pressure, reducing measurement precision
Solution Approach 1:
The spherical body detection unit automatically detects the actual fabric movement amount without requiring user input or manual adjustment. The system serves itself by using the fabric's own movement to generate the detection signal through the spherical body rotation, eliminating the need for external control mechanisms and providing accurate measurement directly from the fabric's actual behavior
Solution Approach 2:
The patent replaces the mechanical cloth feed amount adjustment lever with an optical/electronic detection system using a spherical body and encoder. This substitution eliminates the inaccuracies caused by manual operation and fabric variability, providing precise measurement of actual fabric movement through rotational encoding of the spherical body's position
3Productivity
If the lower thread is supplied according to the estimated moving amount, then the thread supplying process is simple, but the thread tension becomes irregular when actual movement differs from estimated movement, reducing reliability
Solution Approach 1:
The system continuously monitors actual fabric movement through the spherical body detection unit and adjusts the lower thread supplying amount in real-time based on the detected movement. This feedback mechanism ensures that the thread tension remains consistent and reliable, preventing irregularities that would occur with fixed or estimated supplying amounts, while maintaining high productivity through automated adjustment
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 precise detection and adjustment of fabric movement, enhancing thread tension accuracy and reliability, thereby improving stitch quality and consistency across various sewing conditions.
Implementation Method 1
a spherical body (22a) that is exposed partly from the needle plate (2), the spherical body (22a) being rotated following a feed of the fabric (100); an encoder (22c, 22d) that detects a rotation of the spherical body (22a)
Data Source
AI summary
The present invention provides a sewing machine that can actuary detect a physical amount of a movement of a fabric without depending on an estimated value. Thus, thread tension can be precisely adjusted. A sewing machine 1 includes a spherical body 22a exposed partly from a needle plate 2. The spherical body 22a is rotated following a feed of a fabric 100. The rotation of the spherical body 22a is detected by rotary encoders 22c, 22d. A physical amount of the movement of the fabric 100 is calculated based on a detection result of the rotary encoders 22c, 22d. The physical amount of the movement of the fabric 100 is, for example, a moving amount and a moving speed.