| 摘要 |
An impact line printer having a plurality of high velocity, small mass pivoted print hammers. Both a high print density and an unusually high impact printing force is achieved by actuating the hammers by a corresponding plurality of closely packed solenoids whose diameters are substantially larger than the spacing of the print hammers. These solenoids are mounted in the same vertical space but engage their associated print hammers a predetermined distances S1 and S2 from the hammer pivot axis. Appropriate selection of these distances S1 and S2 achieves uniform printing pressures from all of the hammers while using identical solenoids and identical drive currents. A paper engaging clamp includes a driven drive roller mounting a pair of resilient O-rings. A pair of pinch rollers, rotatably mounted on pivoted plastic lever arms, are adapted to clamp the paper or other printing medium between the rollers and the O-rings upon application of a force to the lever arms. The resiliency of the lever arm enables print media of varying thickness to be readily incorporated in printers constructed in accordance with this invention. A simplified pawl and ratchet wheel assembly employing a single spring is used to advance the drive roller. A platen sub-assembly comprises a unitary platen member molded of plastic and including a series of comb-like guides for the print hammers. The top surface of the platen supports the printing media within the impact line printer and the plurality of print hammers as well as the pinch roller support arms are pivoted within the platen member. |
