the moving direction of the hammer bank is opposite to that of the ink ribbon on the other hand when the moving direction of the hammer bank is same as that of the ink ribbon the ink ribbon is moved at the regular speed after a predetermined period of time has been expired when the hammer bank turns around at one end and starts moving in the same direction as the ink ribbon application_number US 65889491 A description in fig2 similar parts or components to those shown in fig1 are denoted by the same reference numerals a dot line printer shown therein includes a platen 12 rotatable about its own axis a hammer bank support member 13 for slidably supporting a hammer bank 1 thereon and a shuttle motor 21 which constitutes a shuttle mechanism 2 together with a cam mechanism not shown the shuttle motor 21 has a rotational shaft and a disk shaped encoder 22 formed with angularly spaced slits is fixed to the upper portion thereof for detecting a position of the hammer bank 1 an optical sensor 23 is disposed in one side of the encoder 22 for sensing light emitted from a light emitting diode not shown disposed in the other side thereof the printer further includes a ribbon drive motor 11 directly coupled to a drive roller 5 as will be described in detail below the rotational speed of the motor 11 is varied substantially in synchronism with the movement of a hammer bank 1 fig3 a indicates a displacement of the hammer bank 1 when it shuttles back and forth at times t 15 and t 16 the hammer bank 1.