Sewing Machine Buttonhole Stitch Position Detection
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Solution Overview
Problem
Existing buttonhole stitch devices in sewing machines face detection errors due to the rickety nature of large and long potentiometers, leading to inaccuracies in stitching length and timing, which affect the quality of the buttonhole stitch.
Innovation Solution
A sewing machine design featuring a presser body with a sliding presser frame, a button holding device, a position detecting device, and a button diameter detecting switch, where the position detecting device measures the shift of the presser frame from the sewing start position, and the button diameter detecting switch ensures the sewing operation is completed to the correct length for the button diameter, enhancing control over the stitching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large and long potentiometer is mounted on the presser member to detect stitching length, then the detection range is sufficient, but the potentiometer becomes rickety and tilted causing detection errors
Solution Approach 1:
The presser member is divided into a fixed presser body and a movable presser frame. The position detecting device is segmented into a sliding base fixed to the presser frame and a sliding member fixed to the presser body. This segmentation allows the detection system to function without requiring a long potentiometer mounted on the presser member, eliminating the rickety and tilted problems while maintaining detection accuracy through the relative movement between the sliding base and sliding member.
2Adaptability or versatility
If the presser frame slidingly moves to accommodate different button sizes, then adaptability is improved, but the arm member coupling the detecting portion becomes long and rickety causing timing errors
Solution Approach 1:
The position detecting function is extracted from the arm member coupling system. Instead of using a long arm member to couple the detecting portion, the invention uses a separate position detecting device with a sliding base and sliding member that directly measures the position of the presser frame without requiring a long coupling arm. This eliminates the flexibility and timing errors associated with long arm members while preserving the adaptability of the sliding presser frame mechanism.
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 design reduces detection errors in stitching length and timing, thereby improving the quality of the buttonhole stitch by accurately controlling the sewing needle and fabric feeding based on the button diameter, ensuring precise stitching.
Implementation Method 1
A potentiometer 105 extending on an outer side of the presser frame 102 along the cloth feeding direction is attached to the presser member 101, and a detecting portion 106 which contacts the potentiometer 105 is attached to the holding portion 104a. The potentiometer 105 includes a variable resistor, and as shown in FIG. 10, when the presser frame 102 moves so that a contacting position of the detecting portion 105 and the potentiometer 105 is varied, a resistance value of the variable resistor varies.
Implementation Method 2
A hollow stopper 102a is fixed to an upper surface of an end portion of the presser frame 102 on a side of a direction A, and a spiral spring 103 is disposed inside the stopper 102a. As shown in FIG. 9, the presser member 101 and stopper 102a are constantly biased toward each other by an elastic force of the spiral spring 103 such that they are in contact with each other at a buttonhole stitch start position.
Data Source
AI summary
The sewing machine includes a presser body, a presser frame, a button holding device including a fixed portion and a sliding portion, a position detecting device including a sliding base attached to the presser frame and a sliding member coupled to the presser body and slidable with respect to the sliding base, a button diameter detecting switch, and a control device. The control device obtains, from the position detecting device, a shift amount of the presser body from a sewing start position when the button diameter detecting switch detects that a sewing operation is carried by a length that corresponds to a diameter of a button, and controls a drive of a sewing needle and the feeding of the workpiece such that a buttonhole stitch corresponding to the diameter of the button is formed.