Sewing machine and computer readable medium

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 movement amount detector that detects a manually fed cloth movement amount;
• 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 cloth movement 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.

A computer readable medium for use in a sewing machine including a controller that controls the sewing machine, 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, the computer readable medium including a sewing machine motor control program, comprising:

• instructions for specifying a stitch pitch to be applied to manually fed sewing operation;
• instructions for detecting a consumed needle-thread amount in each ongoing sewing cycle;
• and
• instructions for controlling:
• sewing speed at the command sewing speed when the command sewing speed is equal to or less than a predetermined constant reference sewing speed;
• 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;
• sewing speed at the reference sewing speed when the target sewing speed is equal to or less than the reference sewing speed;
• and
• sewing speed at the target sewing speed when the target sewing speed is greater than the reference sewing speed.

A computer readable medium for use in a sewing machine including a controller that controls the sewing machine, 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, the computer readable medium including a sewing machine motor control program, comprising:

• instructions for specifying a stitch pitch to be applied to manually fed sewing operation;
• instructions for detecting a manually fed cloth movement amount;
• and
• instructions for controlling:
• sewing speed at the command sewing speed when the command sewing speed is equal to or less than a predetermined constant reference sewing speed;
• sewing speed at a target sewing speed calculated based on the cloth movement amount and the stitch pitch when the command sewing speed is greater than the reference sewing speed;
• sewing speed at the reference sewing speed when the target sewing speed is equal to or less than the reference sewing speed;
• and
• sewing speed at the target sewing speed when the target sewing speed is greater than the reference sewing speed.