Advanced mechanism for inked ribbons or the like

Claim 2

A mechanism for moving an inked ribbon or the like, said mechanism comprising: a frame; a shaft; means to mount said shaft in a position rotatable relative to said frame; a yoke rotatably mounted relative to said shaft; means to maintain said yoke in a fixed axial position relative to said shaft; first and second ratchet wheels mounted concentrically on said shaft, each ratchet wheel having a plurality of teeth extending axially toward each other, said yoke being located in between said ratchet wheels; means to maintain said first ratchet wheel in a fixed axial but rotatable angular position relative to said shaft, said second ratchet wheel being fixed relative to said shaft; a first spool rotatable on said shaft on the side of said first ratchet wheel opposite said teeth thereon; means to hold said first spool in a fixed position relative to said first ratchet wheel; a second spool mounted concentrically on said shaft in a position spaced from one side of said second ratchet wheel, said one side being the side thereof opposite the side thereof on which said teeth are positioned; means to hold said second spool in a fixed position relative to said shaft; bistable means pivotally mounted on said yoke about an axis extending transversely to said shaft, said bistable means including a first spring to bias said bistable means to lie at rest in only one of first and second stable positions at a time; first and second pawl means mounted on said bistable means for movement in a plane generally parallel to the path of movement of said bistable means, said first and second pawl means including a second spring and first and second pawls, said second spring biasing one of said first and second pawls to engage said first and second ratchet wheels, respectively, when said bistable means is in said first and second positions, respectively, said first pawl means being out of engagement with said first ratchet wheel when said second pawl means is in engagement with said second ratchet wheel, and vice versa; and advance means to oscillate said yoke in a manner to cause one of said first and second pawl means to advance a corresponding movable ratchet wheel at least one increment for each yoke oscillation, oscillation of said yoke with one ratchet wheel fixed causing said bistable means to change from one of said first and second stable positions to the other of said first and second stable positions.

Claim 3

The invention as defined in claim 1, including means to mount said shaft in a fixed axial position relative to said frame, an inked ribbon having a first end fixed to said first spool and a second end fixed to said second spool, a pair of brackets fixed relative to said frame to carry said ribbon flat thereacross, pressure means actuable to force a piece of paper and said ribbon against at least one piece of type with the ribbon between said paper and said type, said advance means including a linkage connected between said pressure means and said yoke to cause one oscillation of said yoke each time said pressure means is actuated, and detent means to hold said bistable means in said first and second stable positions thereof.

Claim 4

A selective advancing mechanism comprising: a frame; first and second ratchet wheels rotatable with respect to each other about a first axis extending through said frame, said first and second ratchet wheels having first and second sets of teeth thereon, respectively; bistable means; a first spring to cause said bistable means to lie at rest in only one of first and second stable positions at a time in between said ratchet wheels; said bistable means comprising a plate pivotally mounted about a second axis extending transversely to said first axis; pawl means engaging said first and second ratchet wheels when said bistable means is in said first and second stable positions, respectively, said pawl means lying out of engagement with said first ratchet wheel when said second ratchet wheel is engaged, and vice versa; said pawl means including a pair of arms movable in a plane generally parallel to said plate; advance means actuable to oscillate said bistable means to advance one of said ratchet wheels one predetermined increment for each bistable means oscillation so long as said one ratchet wheel is movable; means to stop movement of said one ratchet wheel, the reactive force of said stopped one ratchet wheel being transmitted to said bistable means via said pawl means to change the position thereof when said bistable means is oscillated by said advance means; a shaft rotatable on said frame about said first axis, said first ratchet wheel being rotatable relative to said shaft and said second ratchet wheel being fixed relative to said shaft; said advance means including a yoke rotatable on said shaft between said ratchet wheels, means to hold said yoke in a fixed axial position on said shaft, means to hold said first ratchet wheel in a fixed axial position on said shaft, said advance means oscillating said yoke about said shaft, said yoke having a flat outer surface portion lying in a plane tangent to an imaginary cylinder concentric with said shaft, said plate being pivoted to said surface portion midway between said ratchet wheels, said plate having two contiguous V-shaped notches in one end thereof, said surface portion having a slit therethrough midway between said ratchet wheels, said first spring being a spring metal wire, said first spring being fixed relative to said yoke and extending through said slit into one of said notches, said notches being divided by a V-shaped projection, said first spring riding over said projection into the other notch when a sufficient force is applied in the correct direction to said plate, said first spring thereby acting as a detent to hold said plate securely in only one of said first and second stable positions at a time, and each said arms of said pawl means being biased toward said first and second ratchet wheels, respectively.

Claim 5

A selective advancing mechanism comprising: a frame; first and second ratchet wheels rotatable with respect to each other about a first axis extending through said frame, said first and second ratchet wheels having first and second sets of teeth thereon, respectively; bistable means; a first spring to cause said bistable means to lie at rest in only one of first and second stable positions at a time in between said ratchet wheels; said bistable means comprising a plate pivotally mounted about a second axis extending transversely to said first axis; pawl means engaging said first and second ratchet wheels when said bistable means is in said first and second stable positions, respectively, said pawl means lying out of engagement with said first ratchet wheel when said second ratchet wheel is engaged, and vice versa; said pawl means including a pair of arms movable in a plane generally parallel to said plate; advance means actuable to oscillate said bistable means to advance one of said ratchet wheels one predetermined increment for each bistable means oscillation so long as said one ratchet wheel is movable; means to stop movement of said one ratchet wheel, the reactive force of said stopped one ratchet wheel being transmitted to said bistable means via said pawl means to change the position thereof when said bistable means is oscillated by said advance means; a shaft rotatable on said frame about said first axis, said first ratchet wheel being rotatable relative to said shaft and said second ratchet wheel being fixed relative to said shaft; said advance means including a yoke rotatable on said shaft between said ratchet wheels, means to hold said yoke in a fixed axial position on said shaft, means to hold said first ratchet wheel in a fixed axial position on said shaft, said advance means oscillating said yoke about said shaft, said yoke having a flat outer surface portion lying in a plane tangent to an imaginary cylinder concentric with said shaft, said plate being pivoted to said surface portion midway between said ratchet wheels, said plate having two contiguous V-shaped notches in one end thereof, said surface portion having a slit therethrough midway between said ratchet wheels, said first spring being a spring metal wire, said first spring being fixed relative to said yoke and extending through said slit into one of said notches, said notches being divided by a V-shaped projection, said first spring riding over said projection into the other notch when a sufficient force is applied in the correct direction to said plate, said first spring thereby acting as a detent to hold said plate securely in only one of said first and second stable positions at a time, and each said arms of said pawl means being biased toward said first and second ratchet wheels, respectively.

Claim 6

The invention as defined in claim 3, wherein said stop means includes a first spool detachably fIxed relative to said first ratchet wheel concentric therewith, and a second spool detachably fixed relative to said shaft concentric therewith.

Claim 7

The invention as defined in claim 4 wherein said stop means further includes an inked ribbon having first and second ends fixed to said first and second spools, respectively, print means to press a piece of paper on top of said ribbon against a piece of type, said advance means including a linkage connected between said print means and said yoke to oscillate said yoke once each time said print means causes a character to be reproduced on said paper, and means to guide said ribbon off of either one of said spools, between the type and the paper, and back onto the other of said spools.