This invention is in the field of sewing machines; more particularly, it is concerned with family sewing machines having a buttonholing capability.
It is well known in the prior art to have family sewing machines having the capability for stitching a complete buttonhole in a single step by utilizing a sliding presser foot which travels with the work material and actuates mechanical or electronic means to implement the turn around at the end of the buttonhole. Such a sewing machine is disclosed in U.S. Pat. No. 4,159,685 of Wurst et al. In this patent an electronically controlled sewing machine is disclosed having the capability to alter the width of the cutting space in the central portion of the buttonhole in order to accommodate, for example, various thickness buttons. An additional problem encountered with generating a buttonhole is that it is not possible to start anywhere on the buttonhole, but only at the beginning of the pattern. If an upper or lower thread breaks or the lower thread supply is depleted, generally the material must be removed from the sewing machine and the stitching already accomplished must be removed from the work material. Thereafter, a new buttonhole may be initiated.
What is required is the capability, in a family sewing machine, for accommodating to an event such as thread breakage or depletion in the middle of a buttonhole without the necessity for thread removal or the unsightly appearance of double stitching on a portion of the buttonhole.