Abstract: A pattern matching sewing machine comprises a sewing means for sewing two superposed sheets of cloth having substantially identical patterns thereon, a feeding means for feeding the two cloth sheets into the sewing means, a detecting means for detecting a mismatch distance between the patterns on the two cloth sheets, and a transport means to transport the two cloth sheets relatively. The pattern displacement amount detected by the pattern mismatch distance amount detecting means may be reduced. A determining means is provided for determining whether pattern matching is possible or not based on the information relating to the mismatch distance obtained by the detecting means.

Abstract: A pattern-matching joining machine for joining two sheets (e.g., sewing two cloths) having the same patterns with the patterns matching. The pattern-sensing photo-sensor generates intensity data for three different colors and the color data processed to correctly discriminate elements of a pattern having colors of similar brightnesses, and to accurately pick out pattern elements with faint colors from behind outstanding pattern elements. One way of processing the data includes calculating differences between intensity data for different colors. Another way includes selecting the color that has the largest intensity change.

Abstract: A device for performing an initial setting of a photosensor of a sewing machine including a light-emitting element and a light-receiving element. The device adjusts the strength of light emitted by the light-emitting element so that the output of the light-receiving element responding to the emitted light falls within a preset normal range. Thus the output from the light-receiving element is normalized and the photo-sensor can correctly discriminate various levels of reflectance, i.e., between a pattern signal and a cloth-edge signal, or among pattern signals of various brightnesses.

Abstract: A pattern-matching sewing machine having a feed-correcting means for accurately adjusting feed amount using a correction factor with three values which are set according to various sewing conditions such as species of cloths and a speed of a main motor. When the feed amount for pattern matching is calculated based on only a mismatch distance detected by a photo-sensor, the accurate pattern matching is not achieved due to the various sewing conditions. Therefore, the feed-correcting means selects the optimum one of the three values to accurately correct the feed amount for a good pattern matching.

Abstract: A pattern-matching sewing machine for sewing two sheets, (e.g. two cloths) having the same patterns with their patterns matching. The sewing machine has a plurality of mismatch calculation modes. The operator selects one of the calculation modes appropriate to the type or characteristics of the pattern to be sewn and the mismatch distance is calculated according to the selected mode.

Abstract: A pattern-matching sewing machine that constantly samples photo-intensity data during calculation of a mismatch distance and during adjustment of the feeding mechanism based on the calculated mismatch distance. When the adjustment is finished, a new mismatch-distance calculation is quickly started, not by waiting for sampling new photo-intensity data of a predetermined number, but by using photo-intensity data of the predetermined number including the data thus sampled during the previous calculation and adjustment, and the previously stored data which have been used in the previous calculation.