Abstract An apparatus and method for feeding a wide-web inking ribbon in alternate directions between a pair of mandrels in an on-the-fly printer. The mandrels are detachably mounted in the printer such that their positions may be interchanged and the locations of the ribbon''s left and right portions reversed. This extends the ribbon''s life when printing is performed only in columns grouped at one side of the document. The apparatus includes means for sensing and correcting skew in the ribbon as it travels between the two mandrels. A photoelectric sensor, positioned adjacent an edge of the ribbon, senses any skew and in response signals a tracking device which axially moves one of the mandrels to overcome the skew. The tracking device includes a movable shaft having a series of teeth thereon which mesh with the teeth of a gear rotatable in either direction by a reversible motor in response to the output of the sensor. Where the ribbon feed is used in a ''''shuttle'''' printer which prints each line by initially printing one group of columns and then ''''shuttling'''' the document to print another group of columns in the line, a pair of sensors are used. They cause the tracking device to move the mandrel so that the ribbon alternately tracks along two paths spaced apart a distance equal to the distance the document is shuttled. This allows substantially the entire area of the ribbon to be used. Even with the usual type of on-the-fly printer which prints in all the columns of a line at one time, the ribbon preferably tracks along two paths. In this case, the distance between the two paths is equal to one-half the distance between adjacent columns so that those areas of the ribbon which would normally always be located at the spaces between the columns are used.
In a printer for printing characters in a print line wherein the gap between each pair of adjacent character positions in said line is greater than the width of a character and wherein ink for said printing is supplied by an inked web mounted on a pair of rotatable mandrels constructed and arranged to feed said web in alternate feed cycles longitudinally past said print line first in one direction perpendicular to said line and then in the opposite direction, means for controlling the feeding of said web comprising, in combination: mandrel positioning means for varying the position of one of said mandrels to shift said web in either direction lateral to its path of movement past said print line; first sensing means positioned adjacent an edge of said web for sensing changes in the lateral position thereof and generating a first output signal indicative of said changes; second sensing means also positioned adjacent said edge of said web and spaced from said first sensing means in a direction parallel to said print line by a distance equal to half the distanCe between adjacent character positions in said print line, said second sensing means adapted to sense changes in the lateral position of said web edge and to generate a second output signal indicative of said changes; control means responsive either to said first output signal or to said second output signal for operating said mandrel positioning means to maintain said web in substantially a fixed lateral position with respect to said first sensing means or said second sensing means as said web feeds past said print line; switch means operable in either a first state for supplying said first output signal to said control means or in a second state for supplying said second output signal to said control means; and means for reversing the state of said switch means coincident with the initiation of each alternate web feed cycle whereby printing is effected from one portion of said web during the feeding of said web in said one direction and from another portion of said web during feeding in said opposite direction.
Claim 2
Dependent Claim
354 words
In a printer for printing characters in a print line wherein the gap between each pair of adjacent character positions in said line is greater than the width of a character and wherein ink for said printing is supplied by an inked web mounted on a pair of rotatable mandrels constructed and arranged to feed said web in alternate feed cycles longitudinally past said print line first in one direction perpendicular to said line and then in the opposite direction, means for controlling the feeding of said web comprising, in combination: mandrel positioning means for varying the position of one of said mandrels to shift said web in either direction lateral to its path of movement past said print line; first sensing means positioned adjacent an edge of said web for sensing changes in the lateral position thereof and generating a first output signal indicative of said changes; second sensing means also positioned adjacent said edge of said web and spaced from said first sensing means in a direction parallel to said print line by a distance equal to half the distanCe between adjacent character positions in said print line, said second sensing means adapted to sense changes in the lateral position of said web edge and to generate a second output signal indicative of said changes; control means responsive either to said first output signal or to said second output signal for operating said mandrel positioning means to maintain said web in substantially a fixed lateral position with respect to said first sensing means or said second sensing means as said web feeds past said print line; switch means operable in either a first state for supplying said first output signal to said control means or in a second state for supplying said second output signal to said control means; and means for reversing the state of said switch means coincident with the initiation of each alternate web feed cycle whereby printing is effected from one portion of said web during the feeding of said web in said one direction and from another portion of said web during feeding in said opposite direction.
Claim 3
Dependent Claim
27 words
The combination set forth in claim 1 wherein said mandrel positioning means comprises means for shifting said one of said mandrels in either direction along its axis.
Claim 4
Dependent Claim
155 words
The combination set forth in claim 2 wherein said first and second sensing means comprise: a support member positioned adjacent said web such that an edge portion of said web passes over said member; first and second photodiodes affixed to said support member in the area of said web edge, said photodiodes being spaced apart from one another in the direction of said print line by a distance equal to half the distance between adjacent character positions in said print line; means for illuminating said photodiodes; and circuit means connected to said photodiodes for generating said first and second output signals in response to the coaction of said web edge with said first and second photodiodes, respectively, each of said first and second output signals being generated at a first level when said web covers the associated photodiode and being generated at a second level when the associated photodiode is exposed to said illuminating means.
Claim 5
Dependent Claim
88 words
The combination set forth in claim 3 wherein said control means comprises bidirectional motor means constructed and arranged to shift said one mandrel in a first direction in response to said first level of said first or said one second output signals and to shift said mandrel in the opposite direction in response to said second level of said first or said second output signals whereby said web is continually shifted laterally back and forth with said web edge positioned over either said first or said second photodiode.