| 摘要 |
1. Printer of the type comprising : - a frame ; - a platen on which a recording material can be supported, this platen being rotatably mounted in the frame on an axis transverse to the recording material, and the rotation of the platen about this axis causing longitudinal forward movement of the recording material ; - a printhead comprising a plurality of printing elements which are aligned in a direction substantially parallel to the axis of the platen and are arranged to be applied to the recording material, itself supported against the platen ; - motor means ; - a crank and connecting rod mechanism in which the crank is driven by the motor means along a circular trajectory, and in which the connecting rod produces relative transverse translational movement of the platen, along its axis, with reference to the printhead, in order to enable the printing of several marks by the same element at distinct transverse positions along a line on the recording material ; - means for advancing the recording material actuated by the motor means to rotate the platen ; and - synchronising means to control the operation of the means for advancing the recording material in synchronism with the drive to the crank and connecting rod mechanism in order to cause rotation of the platen only at the end of printing of a line on the recording material, characterised in that the crank (16, 18) adopts, in each revolution, an even number of predetermined angular positions (P1 to P6), regularly spaced one from another and defining relative transverse positions of the platen (22) with reference to the printhead (20) for each of which printing can be effected, in that these predetermined angular positions (P1 to P6) are disposed, in a symmetrical manner, on either side of a plane which is both diametric for the said circular trajectory and parallel to the direction of the said translational movement, and in that the synchronising means (15, 23, 24) causes rotation of the platen only during each of the intervals of time in which the crank passes from one of the said predetermined angular positions (P3 or P6) to an adjacent predetermined angular position (P4 or P1) while traversing the said diametric plane. |
