Sewing machine external unit

A sewing machine external unit, comprising:

• a holder configured to hold fabric;
• a driver configured to be detachable from a bed of a sewing machine and drive the holder along an upper surface of the bed;
• a position detector configured to detect a position of a sewing needle of the sewing machine in an up-down direction;
• and
• a controller configured to control driving of the holder, which is performed by the driver, based on a detection result of the position detector,
• wherein the holder includes a lower plate and an upper plate configured to hold and sandwich the fabric therebetween, the lower plate is configured to be supported at a position away from the upper surface of the bed by a distance in the up-down direction, the upper plate is movable in the up-down direction with respect to the lower plate, and the driver is configured to support the holder so that the lower plate does not move in the up-down direction,
• wherein the position detector comprises:
• a movable body that is supported by the sewing machine so as to rise together with the sewing needle in response to the sewing needle coming out of the fabric and rising, and has a wavy light shielding pattern formed along the up-down direction;
• and
• a sensor that is supported by the sewing machine in a state where movement in the up-down direction is restricted, and detects movement of the movable body by detecting movement of the wavy light shielding pattern in the up-down direction.