Printing mechanism

Abstract

A mangle wheel having first and second toothed portions arranged in outer and inner arcuate paths forming a continuous loop is rotatably mounted on a support which is pivotally mounted within a housing. A gear is engaged with the continuous loop of teeth to drive the mangle wheel in one direction at a low speed and in the opposite direction at a high speed. A printer head unit is slidably mounted on a guide shaft pivotally mounted on the side walls of the housing. Rotation of the mangle wheel is transmitted to longitudinal movement of the printer head unit to thereby move the same in one direction to effect scanning and in the opposite direction to quickly return the same to the original position. The printer head unit is also movable transversely between an active position in which the head unit is in contact with the plane of a sheet of recording paper and an inactive position disengaged from contact with the paper surface. The support is movable within a limit of travel as the mangle wheel changes its direction of rotation and arranged to move the printer head unit to the inactive position during its return movement.

What is claimed is: 
     
       1. A mechanism .[.for moving a writing unit of a nonimpact type along a straight path to scan across each of a plurality of line paths within a sheet of recording paper, comprising, a housing having a bottom wall and a pair of opposing side walls, a support rotatably mounted on said bottom wall, a mangle wheel rotatably mounted on said support and having first and second toothed portions arranged in an outer and an inner arcuate path to form a continuous loop, a gear engaged with said loop of teeth, drive means for driving said gear whereby said mangle wheel is rotated in one direction at a first speed and in the opposite direction at a second speed higher than said first speed, first guide means arranged to guide said writing unit along said straight path, means for connecting said writing unit with said mangle wheel to cause said writing unit to move in opposite directions, second.]. .Iadd.according to claim 16, including additional .Iaddend.guide means for guiding said recording paper .[., and.]. .Iadd.in a direction normal to said straight path; and shifting .Iaddend.means engageable with said support for .[.stepwisely.]. shifting said paper .[.in a direction normal to the direction of movement of said writing unit,.]. .Iadd.stepwise along said second guide means .Iaddend.when said writing unit moves at said second speed. 
     
     
       2. The mechanism of claim .[.1.]. .Iadd.16.Iaddend., wherein said .[.first.]. .Iadd.writing unit .Iaddend.guide means is movable transverse to the direction of movement of said writing unit between an active position in which said writing unit is in contact with the surface of said paper and an inactive position disengaged from contact with said paper surface and said support is engageable with said .[.first.]. .Iadd.writing unit .Iaddend.guide means to move said writing unit to said inactive position when said mangle wheel changes direction of rotation. 
     
     
       3. The mechanism of claim .[.2.]. .Iadd.17.Iaddend., wherein said .[.first.]. .Iadd.writing unit .Iaddend.guide .Iadd.means .Iaddend.includes a shaft pivotally supported at .[.the.]. opposite ends .Iadd.thereof .Iaddend.by said side walls. 
     
     
       4. The mechanism of claim .[.1.]. .Iadd.16.Iaddend., wherein the center of rotation of said mangle wheel is located at a distance from a pivot about which said support is rotatably mounted so that said support is rotated about said pivot when the engagement of said gear with said loop changes from said first toothed portion to said second toothed portion. 
     
     
       5. The mechanism of claim 4, wherein said .[.first.]. .Iadd.writing unit .Iaddend.guide means has an elongated guide frame, and wherein said .[.rotatable.]. support .[.is provided with.]. .Iadd.has .Iaddend.a first pulley rotatable in unison with said mangle wheel, and second and third pulleys on said pivot, .[.and.]. said elongated frame .[.is provided with.]. .Iadd.having .Iaddend.fourth, fifth and sixth pulleys at one end thereof adjacent said mangle wheel remote from said pivot and a seventh pulley at the opposite end adjacent said pivot remote from said mangle wheel, and .[.wherein.]. a length of wire .[.runs.]. .Iadd.running .Iaddend.from said first pulley, second pulley, fourth pulley and seventh pulley .[.through.]. .Iadd.via .Iaddend.said sixth pulley, fifth pulley to said third pulley and finally to said first pulley, said third pulley being coaxially rotatable with said second pulley and said fourth and fifth pulleys being coaxially rotatable. 
     
     
       6. The mechanism of claim 4, wherein said pivot carries a pulley .[.and.]., .Iadd.means being provided for transmitting .Iaddend.said rotational movement of said mangle wheel .[.is transmitted.]. via said pulley to said writing unit. 
     
     
       7. The mechanism of claim .[.1.]. .Iadd.16.Iaddend., wherein the direction of movement of said support is substantially perpendicular to the direction of movement of said writing unit. 
     
     
       8. The mechanism of claim 1, wherein said shifting means comprises first and second rollers rotatably mounted on said side walls in contact with the circumferential periphery of one another, and a ratchet wheel mounted for rotation with said first roller and engageable with a ratchet pawl mounted on said support. 
     
     
       9. The mechanism of claim 7, .[.wherein.]. .Iadd.including .Iaddend.a manual knob .[.is.]. coupled to said second roller for rotation therewith, .[.and.]. said manual knob .[.includes.]. .Iadd.including .Iaddend.a one-way clutch means to prevent damage occuring .[.on.]. .Iadd.to .Iaddend.said ratchet wheel when rotated in a direction opposite to the direction of movement of said paper. 
     
     
       10. The mechanism of claim 8, wherein .[.the.]. .Iadd.an .Iaddend.intermediate portion of said second roller has a larger diameter than .Iadd.have portions of the second roller .Iaddend. at the opposite ends thereof. 
     
     
       11. The mechanism of claim 1, wherein said .[.second.]. .Iadd.additional .Iaddend.guide means includes a guide channel, .Iadd.and .Iaddend.an elongated plate pivotally supported at .[.the.]. opposite ends thereof within .[.the.]. .Iadd.a .Iaddend.housing .[.and arranged to be in.]. .Iadd.for .Iaddend.contact .Iadd.of the plate .Iaddend.with the .[.plane of said.]. recording paper. 
     
     
       12. The mechanism of claim .[.1.]. .Iadd.16.Iaddend., including a pulse generating mechanism which includes a second gear driven by said drive means .Iadd.and similar to the gear engaged with said loop, .Iaddend.a magnetic core one end of which .[.being.]. .Iadd.is .Iaddend.in proximity to one of the .Iadd.teeth toothed portions .Iaddend.of .Iadd.the mangle wheel engaged by .Iaddend.said .Iadd.second .Iaddend.gear; a coil wound on said magnetic core, a permanent magnet adjacent said coil, and a generally L-shaped member one end of which .[.being.]. .Iadd.is .Iaddend.magnetically coupled to said permanent magnet and the other end of which .[.being.]. .Iadd.is .Iaddend.in proximity to another of said .[.teeth.]. .Iadd.toothed portions of the mangle wheel engaged by said second gear .Iaddend.to thereby form a magnet circuit, whereby a train of pulses are generated from said coil due to variation of magnetic flux in said magnet circuit. 
     
     
       13. The mechanism of claim .[.1.]. .Iadd.16.Iaddend., including a pair of switch contacts operable when said writing unit is in a predetermined position to de-energize said drive means. 
     
     
       14. The mechanism of claim .[.10.]. .Iadd.13 .Iaddend.including a cam rotatable in unison with said mangle wheel and a cam follower resiliently supported .[.on said bottom wall.]. to operate said switch contacts. 
     
     
       15. The mechanism of claim 5, wherein said writing unit is carried on a support having a slot extending parallel with the direction of movement of said writing unit and an eccentric cam having its camming surface knurled and received in said slot, .[.and.]. an extent of said wire between said sixth and seventh pulleys .[.is.]. .Iadd.being .Iaddend.engaged between the adjacent wall of said slot and the knurled surface of said eccentric cam. .Iadd. 16. A writing mechanism comprising; a writing unit of a non-impact type; means for moving the writing unit along a straight path to scan across each of a plurality of line paths within a sheet of recording paper; a rotatably mounted support; a mangle wheel rotatably mounted on said support and having first and second toothed portions arranged in an outer and an inner arcuate path to form a continuous loop; a gear engaged with said loop of teeth; drive means for driving said gear whereby said mangle wheel is rotated in one direction at a first speed and in the opposite direction at a second speed higher than said first speed; writing unit guide means for guiding said writing unit along said straight path; and means connecting said writing unit with said mangle wheel to cause said writing unit to move in opposite directions. 17. A mechanism for moving a writing unit of a nonimpact type along a straight path to scan across each of a plurality of line paths within a sheet of recording paper, comprising; a housing having a bottom wall and a pair of opposing side walls; a support rotatably mounted on said bottom wall; a mangle wheel rotatably mounted on said support and having first and second toothed portions arranged in an outer and an inner arcuate path to form a continuous loop; a gear engaged with said loop of teeth, drive means for driving said gear whereby said mangle wheel is rotated in one direction at a first speed and in the opposite direction at a second speed higher than said first speed; writing unit guide means for guiding said writing unit along said straight path; and means for connecting said writing unit with said mangle wheel to cause said writing unit to move in opposite directions.