Abstract: A sewing machine includes: a needle vertical movement mechanism which moves a sewing needle; a moving mechanism which holds a workpiece by a holding frame; an inner presser-foot device which moves an inner presser foot on an upper side of the workpiece held by the holding frame; a control device which controls the moving mechanism based on sewing data in which stitch positions are defined in order in a series of sewing; and a height detector which detects a height of the inner presser foot. The control device lowers the inner presser foot to an upper surface of the workpiece held by the holding frame, detects the height of the inner presser foot by the height detector, and determines suitability of a thickness of the workpiece, at one or plural stitch positions defined in the sewing data before starting the sewing in accordance with the sewing data.

Abstract: A sewing machine includes: a needle vertical movement mechanism which moves a sewing needle; a moving mechanism which holds a workpiece by a holding frame; an inner presser-foot device which moves an inner presser foot on an upper side of the workpiece held by the holding frame; a control device which controls the moving mechanism based on sewing data in which stitch positions are defined in order in a series of sewing; and a height detector which detects a height of the inner presser foot. The control device lowers the inner presser foot to an upper surface of the workpiece held by the holding frame, detects the height of the inner presser foot by the height detector, and determines suitability of a thickness of the workpiece, at one or plural stitch positions defined in the sewing data before starting the sewing in accordance with the sewing data.

Abstract: A cloth cutting knife 16 is structured such that the length of the cutting edge thereof is set shorter than the length of the side sewing portions of a buttonhole to be formed, and a buttonhole having a length corresponding to the length of the right and left side sewing portions can be formed by moving up and down the cloth cutting knife 16 two or more times. The cloth cutting knife 16 is moved up and down at least once during formation of the stitches of the right and left side sewing portions. Also, the cloth cutting knife 16 is moved up and down once each time a given number of stitches of the right and left side sewing portions are formed. The given number of stitches is set in accordance with both of the length of the cutting edge of the cloth cutting knife 16 and the length of the buttonhole to be formed.

Abstract: A thread cutting device of a sewing machine comprises: a movable knife having a thread pickup portion and being movable between a standby position and a thread pickup position; a fixed knife being movable between a standby position and an operating position close to a needle locating point and cutting sewing threads in cooperation with the movable knife at the operating position; a front stopper for holding the fixed knife at the standby position, wherein the front stopper is released from the fixed knife in the course of the movable knife making a forward movement; and a rear stopper for holding the fixed knife at the operating position, wherein the rear stopper is released from the fixed knife in the course of the movable knife making a backward movement and after the sewing threads have been cut.

Abstract: A buttonhole sewing machine includes a holding mechanism attached to a holder arm which reciprocates in a direction perpendicular to an amplitude direction of a needle. The holding mechanism includes a workpiece holder plate and constitutes a parallelogram linkage. The holding mechanism maintains a parallelogram shape even when the holder plate slants on a fold of the workpiece, and securely holds the workpiece. This buttonhole sewing machine also includes a cutting mechanism which cuts thread and braid in a short manner even when the holder plate slants. The cutting mechanism has a rotary cutter and a fixed cutter, and the fixed cutter is fixed on the holder plate while inclined from a proximal portion to a distal portion. A wire member is connected to the mobile cutter to facilitate the rotation of the rotary cutter even when the holder plate slants.