Sewing Machine Holding-Member Detour Control for Hitch Stitch Avoidance
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Solution Overview
Problem
Existing sewing machines struggle to reliably avoid the formation of hitch stitches, which degrade sewing quality and can lead to thread breakage or inefficiencies due to complex constructions and timing mismatches in detouring mechanisms.
Innovation Solution
A control device for a sewing machine that determines whether the next-stitch forming direction belongs to a predetermined area where a hitch stitch is likely to form, and performs detour control to move the holding member in a direction corresponding to perfect stitch quality, with adjustable settings for detour control based on user needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If detour control is performed to avoid hitch stitches, then sewing quality is improved, but production efficiency deteriorates due to additional movement time
Solution Approach 1:
The patent implements dynamic detour control where the holding member's movement path is adjusted in real-time based on the detected stitch forming direction. When a hitch stitch risk is detected, the system dynamically modifies the trajectory to detour around the needle drop position, then returns to the original path. This dynamic adaptation allows the system to maintain high sewing quality while minimizing the impact on production efficiency by only applying detour control when necessary.
2Reliability
If complex detouring mechanisms are used to avoid hitch stitches, then reliability of avoiding hitch stitches is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical detouring mechanisms with a control device that uses detection and control logic. Instead of physical mechanisms that constantly prepare for detour movements, the system uses a control device to detect stitch forming directions and calculate appropriate detour paths digitally. This substitution of mechanical systems with control logic significantly reduces device complexity while maintaining or improving the reliability of hitch stitch avoidance.
Solution Approach 2:
The control device automatically detects the stitch forming direction and determines whether detour control is needed without requiring external intervention or complex mechanical sensors. The system uses its own control logic to self-adjust the holding member's movement path based on real-time conditions, making the detour control process autonomous and simplifying the overall system architecture.
3Reliability
If timing is precisely controlled for detour movement, then reliability of avoiding hitch stitches is improved, but loss of time increases due to synchronization requirements
Solution Approach 1:
The control device performs preliminary detection of the stitch forming direction before the actual stitching operation begins. By detecting the direction in advance and pre-calculating the necessary detour path, the system can execute the detour movement smoothly without requiring complex real-time synchronization. This preliminary action approach reduces timing constraints and minimizes time loss while ensuring reliable hitch stitch avoidance.
Data Source
AI summary
By a program executed by a CPU, a determination is made as to whether a direction in which a next stitch is to be formed belongs to a predetermined area corresponding to a hitch stitch, and upon determination that the direction in which the next stitch is to be formed belongs to the predetermined area, detour control is performed which includes moving a holding member, holding a sewing workpiece, so as to detour an upper thread, extending downward from a sewing needle, in a direction corresponding to a perfect stitch and then further moving the holding member to a target position corresponding to the next stitch. Various conditions for the detour control are variably set via an operation panel and a program executed by the CPU. Such variable setting can be done by user's operations via the operation panel, by setting detour-controlling data, and/or the like.