Serial dot printer for office machines

Abstract

The printer comprises a solid or liquid ink jet head 100 arranged to print one dot at a time on paper running over a platen 80. The head is carried by a carriage 48 movable transversely with simple harmonic reciprocating motion. In order to reduce the effect of inertial forces when the carriage reverses its movement, the drive is effected by an eccentric peg 70 on a disc 276, the peg engaging in a guide slot 54 of the carriage perpendicular to the direction of reciprocation. An eccentric cam track 71 in the disc engages a peg 92 on a counterweight 90 for counterbalancing the inertial forces of the carriage. In order to synchronize the printing operation with the carriage movement, an optical strobe disc 258 is rigid with the disc 276 and has slots 258 disposed at a pitch varying according to the harmonic motion. The platen 80 is rotated intermittently by a helical cam 277 carried by the disc 276 and a peg wheel 280, 281. In order to compensate for discharge of a smoothing or reservoir circuit feeding the printing head 100, the duration of the pulses applied thereto can be increased in accordance with the rate at which dots are being printed. In a modification the strobe disc is replaced by a linear transducer of capacitive type, with one part carried by the carriage.