Bobbin Thread End Detection Using Printed Bar Code
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Solution Overview
Problem
Conventional methods for detecting the ending-point of a bobbin thread in sewing machines are inaccurate, leading to frequent thread replacements and defects like loose stitches and seam opening, as they struggle to precisely determine when the thread is about to run out.
Innovation Solution
An apparatus and method using a bar code printed on the bobbin to sense the ending-point of the thread, converting the bar code value into a digital signal, and alerting the operator through a speaker, LED, or LCD when the thread is near depletion, ensuring timely replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical sensor is used to detect the ending point of bobbin thread, then the detection can be performed continuously, but the measurement precision is low and cannot accurately sense the finishing point
Solution Approach 1:
The patent applies the copying principle by creating a bar code pattern on the bobbin surface that represents the thread position. Instead of directly detecting the physical thread end with complex sensors, the system copies the thread position information into a readable bar code format, which can then be detected with simple optical readers. This transforms a complex continuous detection problem into a simple discrete code reading problem.
Solution Approach 2:
The patent replaces the mechanical/optical sensor system with an information-based system. Instead of using physical sensors to detect thread position, the system uses a bar code (information carrier) that encodes the position data. The detection is then performed by reading this information with a simple optical reader, substituting complex mechanical sensing with information processing.
2Productivity
If the bobbin thread is made shorter to fit in the hook-set, then the sewing machine can operate properly, but the frequency of thread replacement increases
Solution Approach 1:
The patent applies preliminary action by marking the bar code on the bobbin before the thread is fully consumed. The bar code serves as an advance warning system that allows the operator to replace the thread before it completely runs out, preventing production interruptions. This proactive approach eliminates the need for reactive thread replacement after the thread actually ends.
3Measurement precision
If the bar code is printed on the bobbin surface, then the ending point can be detected accurately, but the bobbin structure becomes more complex
Solution Approach 1:
The patent applies the color changes principle by using a bar code pattern with varying optical properties (dark and light bands) on the bobbin surface. This pattern creates distinct optical contrasts that can be easily detected by optical readers, providing high measurement precision without requiring complex bobbin structures. The bar code essentially uses optical contrast to encode position information.
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
Prevents product defects by accurately alerting operators when the bobbin thread is running low, improving sewing efficiency and reducing the frequency of thread replacements.
Implementation Method 1
a bar code detector (170) for detecting the ending-point of a bobbin thread wound around a bobbin (100) and alerting a sewer of the ending-point
Data Source
Figure 1~2(c)
AI summary
The present invention relates to an apparatus and a method for detecting the ending-point of a bobbin thread for a sewing machine using a bar code, which is capable of alerting a sewing operator of his/her desiring bobbin thread remains when they are left enough to finish sewing under operation. The present invention of the apparatus for detecting the ending-point of a bobbin thread for a sewing machine using a bar code so as to sense the ending-point of a bobbin thread during a sewing operation, comprises a bobbin to wind a bobbin thread therearound and at least one bar code to indicate a position in the surface of a bobbin, of which the bar code is printed on one or both side(s).