| 摘要 |
PURPOSE:To make a printing density adjustable, by a method wherein; in a dot impact printer comprising a printing hammer, an elastic member, a permanent magnet, demagnetizing coils, and a drive circuit, a current is passed from the drive circuit to the demagnetizing coils to adjust a current-passing time. CONSTITUTION:A dot impact printer comprising; an elastic member 1 having a fixed end and a movable end provided with the printing hammer 6, a perma nent magnet 2 attracting the movable end, demagnetizing coils 5 cancelling the flux of the permanent magnet 2, and a drive circuit supplying an electric current to the demagnetizing coils 5. In the drive circuit, a demagnetizing elec tric current is supplied to the demagnetizing coils 5 according to the ON-OFF action of a transistor 27 in a switching circuit 21. A diode 28 is used for absorb ing the surge generating in the demagnetizing coils 5. In this manner, an impact printing is conducted with use of the elasticity of the elastic member 1 produced when the attraction of the movable end of the elastic member 1 is released. Additionally, in the switching circuit 21, the ON-OFF time of the transistor 27 is corrected by a correcting signal sent from a correcting circuit 20, which realizes an adjustable printing density. |
