Ribbon transporting and reversing mechanism

Claim 2

Ribbon transporting and reversing mechanism comprising first and second units, each unit being operable between a wind up position for winding up a ribbon and a let off position for unwinding the ribbon, said mechanism having a first operational condition in which said first unit is in said wind up position and said second unit in said let off position, and a second operational condition in which said first unit is in said let off condition and said second unit is in said wind up condition; each unit comprising biassed control means having a normal position for guiding the ribbon to the control means of the respective other unit, and an actuated position for shifting said mechanism between said first and second operational conditions, said control means of both units being urged by the ribbon to said actuated position when the ribbon is fully wound up by one unit and completely unwound from the other unit and thereby tensioned; and biassed sensing means for sensing the diameter of the ribbon coil and moving to an inoperative position when sensing a coil, and to a blocking position blocking the respective control means when sensing the end of the ribbon so that said control means of said other unit whose ribbon is completely unwound is blocked in said normal position, and only the control means of said one unit whose ribbon Is fully wound up is moved by said tensioned ribbon to said actuated position and operates said one unit to assume said let off position and said other unit to move to said wind up position whereby the direction of the movement of the ribbon is reversed.

Claim 3

A mechanism as claimed in claim 1 wherein said sensing means and said control means of each unit include a sensing lever and a control lever; and wherein said sensing lever extends transversely to said control lever and has a pivot axis and a free end engaging said control lever in said blocking position and releasing said control lever in said inoperative position, and a sensing portion between said pivot axis and said free end for sensing the ribbon coil; and means mounting said sensing lever for angular movement about said pivot axis between said inoperative and blocking positions and positioning said sensing lever so that said free end moves along a flat arc substantially parallel with said control lever in said normal position.

Claim 4

A mechanism as claimed in claim 1 wherein each unit comprises a support, and a spool for winding up the ribbon and mounted on said support for turning movement about a first axis; wherein said control means is mounted on said support for turning movement about a second axis; wherein said sensing means is mounted on said support for turning movement about a third axis, and wherein said second and third axes are located on opposite sides of said first axis

Claim 5

A mechanism as claimed in claim 3 wherein said control means, ribbon spool, and sensing means are substantially located in the same plane in which said ribbon is located; and wherein the distance from said third axis to said control means and to the portion of said sensing means engaging said control means for blocking said control means is substantially twice the distance from said third axis to said first axis and thereby to the portion of the ribbon coil sensed by said sensing means.

Claim 6

Ribbon transporting and reversing mechanism including first and second units alternately serving as wind up and let off units for a ribbon extending between said units, connecting means connecting said units, and actuating means; each unit comprising; a support; a ribbon spool mounted on said support for rotation, said ribbon extending between said ribbon spools of said units and having ends secured to said ribbon spools; drive means actuated by said actuating means and having an inoperative position, and an operative position for rotating the ribbon spool of the respective unit; shifting means for shifting said drive means between said inoperative and operative positions, said shifting means of said units being connected by said connecting means for movement between first and second positions for shifting said drive means of each unit to said operative position while shifting the drive means of the respective other unit to said inoperative position; biassed control means having a normal position for guiding the ribbon between said spools to the control means of the respective other unit, and an actuated position for shifting said shifting means and thereby said connecting means and said shifting means of the respective other unit between said first and second positions, said control means of both units being urged by the ribbon to said actuated position when the ribbon is fully wound up on the driven spool of one unit and completely unwound from said spool of the other unit and thereby tensioned by said drive means of said driven spool of said one unit; and biassed sensing means for sensing the diameter of the ribbon coil wound up on said spool and moving to an inoperative position when sensing a coil, and to a blocking position blocking movement of said control means to said actuated position when sensing the end of the ribbon so that said control means of the unit whose ribbon is unwound is blocked in said normal position, and only the control means of said one unit whose ribbon is fully wound up is moved by said tenSioned ribbon to said actuated position and operates said shifting means and connecting means to move said drive means of said one unit to said inoperative position and said drive means of said other unit to said operative position whereby the direction of movement of the ribbon is reversed.

Claim 7

Ribbon transporting and reversing mechanism including first and second units alternately serving as wind up and let off units for a ribbon extending between said units, connecting means connecting said units, and actuating means; each unit comprising; a support; a ribbon spool mounted on said support for rotation, said ribbon extending between said ribbon spools of said units and having ends secured to said ribbon spools; drive means actuated by said actuating means and having an inoperative position, and an operative position for rotating the ribbon spool of the respective unit; shifting means for shifting said drive means between said inoperative and operative positions, said shifting means of said units being connected by said connecting means for movement between first and second positions for shifting said drive means of each unit to said operative position while shifting the drive means of the respective other unit to said inoperative position; biassed control means having a normal position for guiding the ribbon between said spools to the control means of the respective other unit, and an actuated position for shifting said shifting means and thereby said connecting means and said shifting means of the respective other unit between said first and second positions, said control means of both units being urged by the ribbon to said actuated position when the ribbon is fully wound up on the driven spool of one unit and completely unwound from said spool of the other unit and thereby tensioned by said drive means of said driven spool of said one unit; and biassed sensing means for sensing the diameter of the ribbon coil wound up on said spool and moving to an inoperative position when sensing a coil, and to a blocking position blocking movement of said control means to said actuated position when sensing the end of the ribbon so that said control means of the unit whose ribbon is unwound is blocked in said normal position, and only the control means of said one unit whose ribbon is fully wound up is moved by said tenSioned ribbon to said actuated position and operates said shifting means and connecting means to move said drive means of said one unit to said inoperative position and said drive means of said other unit to said operative position whereby the direction of movement of the ribbon is reversed.

Claim 8

A mechanism as claimed in claim 5 wherein said ribbon spool of each unit is mounted for rotation about a first axis; wherein said control means of each unit is mounted on said support for turning movement about a second axis; wherein said sensing means of each unit is mounted on said support for turning movement about a third axis; and wherein said second and third axes are located on opposite sides of said first axis in each unit.

Claim 9

A mechanism as claimed in claim 6 wherein said control means, ribbon spool, and sensing means are substantially located in the same plane in which said ribbon is located; and wherein the distance from said third axis to said control means and to the portion of said sensing means engaging said control means for blocking said control means is substantially twice the distance from said third axis to said first axis and thereby to the portion of the ribbon coil sensed by said sensing means.

Claim 10

A mechanism as claimed in claim 5 wherein said drive means of each unit include a ratchet wheel connected with said ribbon spool for turning movement, and biassed pawl means including a shifting pawl cooperating with said ratchet wheel; wherein said actuating means include a reciprocating actuating member in each unit carrying and reciprocating said shifting pawl so that said ratchet wheel and said ribbon spool of said one unit are stepwise turned for winding up the ribbon in one direction only; and wherein said shifting means of each unit has a cam portion cooperating with said pawl means for holding the pawl means of said other unit spaced from said ratchet wheel so that the ribbon can be freely unwound from said ribbon spool of said other unit.

Claim 11

A mechanism as claimed in claim 11 wherein said pawl means of said drive means of each unit comprise a holding pawl mounted on said support, and a spring connecting said shifting pawl with said holding pawl and biassing said pawls to engage said ratchet wheel.

Claim 12

A mechanism as claimed in claim 9 wherein said control means, said sensing means, said ratchet wheel, said shifting and holding pawls, and said shifting means are made of a light synthetic plastic material.