Ribbon feed and correction device for a high speed printer

Claim 2

In combination with a device for evenly winding a web onto a spool of the type comprising a fixed machine frame, a twistable frame means mounted on said machine frame, said twistable frame means capable of assuming either of two states of twist, a first and a second spooling means, said first and second spooling means pivotally and rotatably mounted in said twistable frame means, said two states of twist imparting alternate states of relative skew between said first and said second spooling means, said first spooling means winding said web from said second spooling means and said second spooling means winding said web from said first spooling means, a rotary driving means for rotatably driving said first and second spooling means, a web axialposition detection means, a reciprocating drive means, said reciprocating drive means intermittently actuated by said detection means when a change is detected in the axial-position of said web as it is wound upon either said first or said second spooling means, said twistable frame means driven by said reciprocating drive means so as to assume either of said two states of twist, said web steered into alternate directIons of axial motion on said first or said second spooling means by said alternate states of relative skew, said state of skew controlled by said detecting means sensing the presence or absence of said web at a reference point substantially midway between the extreme axial displacements of said web, wherein the improvement resides in said reciprocating drive means which further comprises: a ratchet means continuously driven by said rotary driving means, a pawl means opposed to said ratchet means and intermittently engagable therewith under the control of said web axialposition detection means, a rotary-to-reciprocating motion conversion means connected to said pawl means, said motion conversion means being intermittently driven by said pawl means when said detection means causes said pawl means to engage said ratchet means, said rotary-to-reciprocating motion conversion means contacting to said machine frame and said twistable frame means so as to impart a relative displacement therebetween when driven by said pawl means.

Claim 3

In the improved device for evenly winding a web onto a spool of claim 1, wherein said web axial-position detection means further comprises: a sensing cam, rotatably mounted on said twistable frame means and continuously driven by said rotary driving means, said sensing cam having at least one lobe, a sensing arm, mounted on said twistable frame means and resiliently urged into engagement with said sensing cam, said sensing arm periodically displaced by the lobes on said cam, through an arc over said reference point, said sensing arm undergoing relatively large displacements when said web is present and relatively small displacements when said web is absent from said reference point,

Claim 4

In the improved device for evenly winding a web onto a spool of claim 2, wherein said reciprocating drive means further comprises: said ratchet means, rotatably mounted on said twistable frame means and continuously driven by said rotary driving means, said ratchet means possessing a number of teeth equal to the number of lobes on said sensing cam, said ratchet means rotating in unison with said sensing cam, a pawl carrier means, said carrier means rotatably mounted on said twistable frame means in a position coaxial with and opposed to said ratchet means, a first pawl, pivotally mounted on said carrier means, said first pawl mounted so as to be resiliently urged into engagement with said ratchet means when said ratchet means undergoes clockwise rotation, a second pawl, pivotally mounted on said carrier means, said second pawl, mounted so as to be resiliently urged into engagement with said ratchet means when said ratchet means undergoes counterclockwise rotation, a resilient detent means mounted on said twistable frame means and positioned so as to stop the rotation of said pawl carrier means at every 180*, said sensing arm periodically contacting and pivotally displacing said first and said second pawls, as it is driven by said sensing cam in timed rotation with the rotation of said ratchet means, said pawl displacement causing said first pawl to avoid engagement with said ratchet means during clockwise rotation of said ratchet and causing said second pawl to avoid engagement with said ratchet during counterclockwise rotation of said ratchet, said sensing arm omitting contact with said first pawl during clockwise rotation of said ratchet or omitting contact with said second pawl during counterclockwise rotation of said ratchet, when a change in the magnitude of said periodic displacements of said sensing arm occurs, said displaced pawl engaging said ratchet means when said change in the magnitude of said sensing arm displacements takes place, said pawl carrier means thereby being driven into rotation, said pawl carrier rotation continuing until said detent means halts said rotation, at which point said sensing arm contacts said engaged pawl, disengaging said pawl, said pawl carrier means remaining stationary in its new state as long as said periodic sensing arm displacements retain their new magnitude.

Claim 5

In the improved device for evenly winding a web onto a spool of claim 3 wherein said reciprocating drive means further comprises: a correction cam rotatably mounted on said twistable frame means and rotating in unison with said pawl carrier means, a cam follower rigidly attached to said machine frame, said correction cam rotatably mounted within said cam follower, said twistable frame means undergoing a twist displacement when said correction cam is rotatably driven by 180* within said cam follower by means of the controlled rotation of said pawl carrier means, said state of relative skew of said first and second spooling means being altered by the controlled displacement of said twistable frame means, said web being steered into alternate directions of axial motion along said first and second spooling means, by the controlled changes in said relative skew, whereby said web may be evenly wound on either said first or said second spooling means, automatically.

Claim 6

In the improved device for evenly winding a web onto a spool of claim 1, wherein the rotary driving means further comprises: a first reversible motor mounted on said twistable frame means, said first motor driving said first spooling means, a second reversible motor mounted on said twistable frame means, said second motor driving said second spooling means, said first motor, when driving said first spooling means so as to wind said web thereupon, being fully energized to advance the web, while said second motor being energized in the direction opposing the advance of the web, at a magnitude of substantially one half that of said first motor, thus imparting a drag force on the web, an end-of-web reversing means for detecting the end of the web before it unwinds from the spooling means supplying said web, said reversing means automatically reversing the driving direction of said first and second motors, said second motor becoming fully energized so as to advance the web in the direction reversed to its preceding motion and said first motor becoming energized at one half its preceding magnitude and in the direction opposed to the new direction of advance for the web, whereby said web remains in tension without regard to its direction of advance.

Claim 7

In the improved device for evenly winding a web onto a spool of claim 1, wherein the web axial-position detection means further comprises: a sensing cam continuously driven by said rotary driving means, a sensing arm mounted on said twistable frame means so as to be resiliently urged into engagement with said sensing cam, said sensing arm being periodically lifted and lowered over said reference point by means of said sensing cam, a collapsible finger means, pivotally mounted on said sensing arm, said finger means located substantially over said reference point, said finger means frictionally engaging said web when present at said reference point, when said cam lowers said sensing arm, said finger means following the advancing motion of said web, when frictionally engaging the web causing the finger means to collapse and the sensing arm to undergo a relatively large displacement, said finger means remaining in a standing position on a supporting surface for said web, when said web is absent from said reference point, when said sensing cam lowers said sensing arm, thereby limiting the sensing arm to a relatively small displacement, said sensing arm periodically actuating said pawl means as said sensing cam lifts and lowers said sensing arm, said rotary-to-reciprocating motion conversion means being driven by said pawl means when the magnitudes of the periodic displacements of said sensing arm change, said changes in magnitude of said sensing arm displacement correSponding to axial motion of the edge of said web at said reference point, the change from small to large magnitude indicating the presence of said web and the change from large to small magnitude indicating the removal of said web at said reference point.

Claim 8

In the improved device for evenly winding a web onto a spool of claim 1, wherein the rotary-to-reciprocating motion conversion means further comprises: a correction cam rotatably mounted on said twistable frame means and intermittently driven by said pawl means, a cam follower rigidly attached to said machine frame, said correction cam rotatably mounted within said cam follower, said twistable frame means undergoing said twist displacement when said correction cam is rotatably driven within said cam follower by means of said pawl means.

Claim 9

In the improved device for evenly winding a web onto a spool of claim 1, wherein the pawl means further comprises: a pawl carrier means, said carrier means rotatably mounted on said twistable frame means in a position coaxial with and opposed to said ratchet means, a first pawl, pivotally mounted on said carrier means, said first pawl being resiliently urged into engagement with said ratchet means when said ratchet means undergoes clockwise rotation, a second pawl, pivotally mounted on said carrier means, said second pawl being resiliently urged into engagement with said ratchet means when said ratchet means undergoes counterclockwise rotation, said web axial-position detection means contacting and pivotally displacing said first and second pawls in timed relation with the rotation of said ratchet means, said displacements causing each of said pawls to avoid engagement with said ratchet.