Sewing machine with automatic thread cutter

A thread cutting method by an automatic thread cutter in a sewing machine, comprising the steps of:

• decreasing a rotational speed of a machine motor from a high speed to a low speed;
• detecting a threshold medium speed during decreasing of the rotational speed of said machine motor by the decreasing step;
• reducing a work fabric feed pitch of at least one stitch after detection of the threshold medium speed by the detecting step;
• and
• cutting a needle thread and a bobbin thread after execution of the reducing step.

A sewing machine with an automatic thread cutter, comprising:

• speed command means for generating a speed command signal for decreasing a rotational speed of a machine motor from a high speed to a low speed;
• thread cutting means for cutting a needle thread and a bobbin thread;
• feed pitch changing means for reducing a work fabric feed pitch of at least one stitch just before thread cutting according to said speed command means;
• threshold detecting means for detecting a threshold medium speed during decreasing of the rotational speed of said machine motor by said speed command means;
• feed pitch control means for driving said feed pitch changing means after detection of said threshold medium speed by said threshold detecting means;
• thread cutting control means for generating a thread cutting operation signal to said thread cutting means after driving of said feed pitch changing means by said feed pitch control means;
• and
• needle position detecting means for detecting a needle-up position where a needle is present near a top dead center of a needle stroke and a needle-down position where the needle is present near a bottom dead center of the needle stroke, wherein when the needle-down position is detected by said needle position detecting means after the threshold medium speed has been detected, said feed pitch changing means is driven by said feed pitch control means.