| 摘要 |
PURPOSE:To reduce a heat generation quantity largely, by feeding a driving current to a stepper motor according to the load of a body to be driven, receiving the signal from a sensing means which outputs the signal associated with the load of the body to be driven. CONSTITUTION:When a needle bar 10 is at a highest position, the phase angle of an upward axis is made to be zero degree. In this case, in the period of from about 90 degrees to about 105 degrees inclusive, wherein a large load acts on the needle bar 10 when a sewing needle 13 is stuck into a processed cloth, an emitted light from a light emission element is shaded with a shielding plate 12. Therefore, in this period, a photointerrupter 11 outputs a load signal LS of 'L' level which commands the needle bar 10 to bear a high load, and in the period other than this period, outputs the load signal LS of 'H' level which commands it to bear a low load. Still, the needle bar 10 continues to lift, and when the phase angle has reached about 260 degrees, the photointerrupter 11 outputs the load signal LS of 'L' level, but this load signal LS doesn't affect the control of a driving current. Numerals 14 and 15 denote a presser bar and presser foot respectively. |
