Sewing Machine Thread Tension Evaluation via Image Analysis
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Solution Overview
Problem
Conventional sewing machines rely on subjective user evaluation for thread tension balance, leading to imprecise adjustments and difficulties for inexperienced users, with existing automatic systems being affected by ambient light and fabric features.
Innovation Solution
A sewing machine equipped with an image capturing unit to analyze stitches from both sides of the fabric, extracting and calculating the area of interlaced threads to evaluate and adjust tension balance automatically, independent of user discretion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If visual observation of test stitches is used for tension balance evaluation, then the evaluation can be performed with simple equipment, but the evaluation precision becomes ambiguous and subjective
Solution Approach 1:
The patent replaces the mechanical/visual observation system with an optical detection system. A line sensor detects the reflective light from the seam to objectively measure the depth of interlace and evaluate tension balance, eliminating subjective visual assessment while maintaining relatively simple equipment requirements.
Solution Approach 2:
The patent introduces reflective light as an intermediary to transfer information about thread interlace depth to the detection system. By detecting the reflective light characteristics, the system can indirectly measure the tension balance without direct contact or complex mechanical measurement devices.
2Device complexity
If reflective light detection is used to measure seam depth, then the detection can be performed with optical equipment, but the detection precision is affected by ambient light and fabric features
Solution Approach 1:
The patent uses color filters to selectively detect specific wavelength ranges of reflective light. By analyzing the color characteristics of the reflected light from different fabric surfaces, the system can compensate for variations in fabric features and ambient light conditions, improving detection reliability.
Solution Approach 2:
The patent employs periodic illumination with the light source, emitting light in pulses or cycles. This periodic action allows the detection system to distinguish between ambient light and the illuminated seam, reducing the impact of ambient light interference on detection precision.
3Productivity
If automatic tension balance adjustment is implemented, then the productivity increases and user skill requirement decreases, but the system complexity increases
Solution Approach 1:
The patent implements a feedback control system where the line sensor continuously detects the tension balance state, and the controller automatically adjusts the thread tension based on this feedback. This closed-loop control achieves automatic tension balance adjustment with relatively simple system architecture, improving productivity without excessive complexity.
Solution Approach 2:
The system performs self-adjustment of thread tension based on real-time detection of stitch quality. The automatic adjustment mechanism eliminates the need for operator intervention in tension balancing, making the system self-sufficient in maintaining optimal sewing conditions.
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 approach provides precise and reliable automatic evaluation and adjustment of thread tension balance, unaffected by ambient light or fabric characteristics, improving sewing quality and usability.
Implementation Method 1
The above mentioned needle thread and bobbin thread detectors impinge a slit light on the seams of the workpiece cloth and detect the reflective light with a line sensor
Data Source
AI summary
A sewing machine including an image capturing unit disposed at a position capable of capturing images of the stitches formed on the workpiece cloth and capturing images of the stitches at least from either upper and undersides of the workpiece cloth; an extracting section that extracts, from the image data of the stitches captured by the image capturing unit, a region occupied by an opposite side thread appearing at an interlace of the needle thread and the bobbin thread; a calculating section calculating an area of the extracted region; an evaluating section that evaluates a tension balance between the needle thread and the bobbin thread based on the area calculated by the calculating section; and a controller controlling the thread tension adjustment mechanism to modify the tension balance of the stitches based on a result of evaluation by the evaluating section.