Sewing – Elements – Starting or stopping
Patent
1986-06-11
1988-09-27
Nerbun, Peter
Sewing
Elements
Starting or stopping
D05B 6926
Patent
active
047733446
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a sewing machine control device and, more particularly, to improvements in a sewing machine control device whereby a sewing machine can be precisely and effectively stopped at the termination point of a seam.
BACKGROUND TECHNOLOGY
In sewing machines generally, it has been known that at the sewing termination point of one of a plurality of continuous sewn portions of a workpiece or at the termination point of the sewing operation for all the sewn portions, the sewing machine must be precisely stopped so that the seam or seams will not deviate from the end of the workpiece.
Hithertofore, a variety of methods for stopping sewing machines in such a manner have been attempted.
According to the first method, when a seam is formed to finish at a position adjacent to an end edge of a workpiece where the sewing operation is scheduled to terminate, the operator reduces the force applied to the pedal so that the sewing machine is driven at a low speed, stops the machine when the seam reaches the predetermined sewing termination point and then depresses the pedal again to effect thread cutting. However, this method requires that the operator controls the pedal with great care. According to the second method, a workpiece detector means utilizing light is disposed upstream of the sewing zone in the sewing machine in the workpiece feed direction and the sewing machine stops automatically as the trailing end edge of a workpiece passes by the workpiece detector means independently of the pedal control. However, this method involves the drawback that when a seam is formed along an end edge of a workpiece having a complicated configuration such as a wave or concavo-convex shape, for example, the workpiece end edge tended to deviate at concavo-convex corners thereof from its proper position with respect to the workpiece detector means whereby the sewing machine is inadvertently stopped. This results in a substantial reduction of operation efficiency.
According to the third method, when a workpiece detector means detects the trailing end edge of a workpiece, the sewing machine stops and a thread cutter means is operated. However, this method involves the drawback that when a seam is formed along an end edge of a piece of cloth having a complicated configuration or of a piece of cloth having a square configuration such as a neck, collar, sleeve or cuff, each time the workpiece end edge deviated at a corner of square or concavo-convex configuration from its proper position with respect to the workpiece detector means, the sewing machine stops and the thread cutter means is operated, thereby making it impossible to form a continuous seam along the workpiece end edge and impairing the quality of a sewn product.
DISCLOSURE OF THE INVENTION
The purpose of the present invention is to provide a sewing machine control device which eliminates the drawbacks inherent in the prior art.
According to the present invention, in order to attain this purpose the sewing machine is driven or stopped in response to the operation of the pedal and when a workpiece detector means disposed upstream of the sewing zone in the machine in the workpiece feed direction detects the trailing end edge of a workpiece, the sewing machine is automatically stopped independently of the above-mentioned operation of the pedal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic front elevational view of the sewing zone in a sewing machine embodying the present invention;
FIG. 2 is an explanatory view showing the formation of a seam on a workpiece W by the embodiment of FIG. 1;
FIG. 3 is a block diagram of the main electrical circuit in the embodiment;
FIG. 4 is a time chart of the electrical circuit of FIG. 3;
FIG. 5 is a diagram of the control circuit of the motor and sewing machine operation means in the embodiment; and
FIG. 6 is a flow chart for controlling the motor and thread cutter.
BEST MODE FOR CARRYING OUT THE INVENTION
First referring to FIG. 1, there is schematically shown a portion of a sewing mach
REFERENCES:
patent: 4160424 (1979-07-01), Newell et al.
patent: 4403558 (1983-09-01), Martell et al.
patent: 4513676 (1985-04-01), Martell et al.
patent: 4555997 (1985-12-01), Tancs
Sunada Toshiaki
Yasui Hideo
Nerbun Peter
Tokyo Juki Industrial Co., LTD
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