NEEDLE POSITION DETECTOR

PURPOSE:To provide a needle position detecting device which can by easily adjusted and has a simple structure by providing an optical sensor and a light shielding plate and allowing a signal reversal part installed onto the light shielding plate to correspond to the lower needle position or upper needle position. CONSTITUTION:The lower needle position is adjusted by loosening a stop screw 2 fixed onto the upper shaft of a sewing machine and turning the sewing machine to a lower needle position state and adjusting the position where the lower needle position and the cut part 243 of a sensor 24 coincide and tightening the stop screw 2 and then carrying out fixation. Further, the upper needle position is adjusted by turning the sewing machine to a lower needle position state and slightly loosening a screw 14 and turning a light shielding plate 23 and carrying out fixation by tightening the screw 14 again at the position where the upper needle position and the cut part 243 of the optical sensor 24 coincide. In this case, a projection part 291 is formed between a light shielding plate A22 and a light shielding plate B23, and a spacer 29 is inserted for preventing revolution. Therefore, the light shielding plates A, B22, and 23 can be adjusted independently in any revolution direction, and even if the shaft 1 is fixed onto the upper shaft of the sewing machine by the stop screw 2, adjustment to the upper or lower needle position is permitted.