Patent ID: 8037834

Claim:
A sewing machine, comprising: a sewing machine motor that vertically drives a sewing needle via a main shaft; a sewing speed commander that produces a command sewing speed determined by rotational speed of the sewing machine motor; a stitch-pitch specifier that specifies a stitch pitch to be applied to manually fed sewing operation; a consumed thread amount detector that detects a consumed needle-thread amount in each ongoing sewing cycle; and a sewing speed controller that: controls sewing speed at the command sewing speed when the command sewing speed is equal to or less than a predetermined constant reference sewing speed, and that controls sewing speed at a target sewing speed calculated based on the consumed needle-thread amount and the stitch pitch when the command sewing speed is greater than the reference sewing speed; controls sewing speed at the reference sewing speed when the target sewing speed is equal to or less than the reference sewing speed; and controls sewing speed at the target sewing speed when the target sewing speed is greater than the reference sewing speed.