Patent ID: 7162966

Claim:
Sewing or embroidery machine ( 1 ), comprising a hook ( 15 ) that can be driven by a drive motor and with a lower-thread bobbin ( 17 ) supported rotatably in the hook ( 15 ) for holding a lower-thread supply ( 37 ), the bobbin having a spindle and annular flanges ( 21 , 22 ) set on ends of the spindle, at least one of the flanges ( 21 ) is perforated with a plurality of holes ( 19 ), and a light source ( 35 ) arranged axially in front of or behind the lower-thread bobbin ( 17 ), a light receiver ( 39 ) arranged in front of or behind the lower-thread bobbin ( 17 ) for receiving light beams emitted by the light source ( 35 ), a calculating and control unit for processing received signals supplied by the light receiver ( 39 ), wherein radially outer peaks (S′) of the holes ( 19 ) in at least one of the flanges ( 21 ) of the lower-thread bobbin ( 17 ) have different distances from a rotational axis (A) of the lower-thread bobbin ( 17 ); wherein centers of the holes ( 19 ) or the outer peaks (S″) of the holes ( 19 ) are arranged along a line (L′) which extends in a spiral relative to the rotational axis (A) of the bobbin ( 17 ).