Patent ID: 7806063

Claim:
An electronic sewing machine, comprising: a sewing machine motor that vertically drives a sewing needle via a rotation of a main shaft; a stitch-pitch setting unit that sets a stitch-pitch in sewing manually fed workpiece cloth; a consumed thread amount detection unit that detects consumed thread amount of at least either of a needle thread or a bobbin thread consumed in each ongoing sewing cycle; a consumed thread amount calculation unit that calculates consumed thread amount based on an output from the consumed thread amount detection unit; and a speed control unit that controls rotational speed of the sewing machine motor based on calculated result of the consumed thread amount calculation unit so that an amount of manual cloth feed equals the stitch-pitch set by the stitch-pitch setting unit; wherein the consumed thread amount detection unit determines the consumed thread amount in each of the sewing cycles after a rotational phase angle of the main shaft reaches a predetermined rotational phase angle at which rotational phase angle the sewing needle strikes the workpiece cloth.