Printing machines of the kind described for example in Keller et al. U.S. Pat. No. 5,833,377 utilize a thermal transfer “inked” ribbon wound upon a core, the core in turn being mounted upon a spindle of the machine (see for example
Despite extensive prior art activity and the commercial availability of a considerable variety of suitable products, a need remains for an inked ribbon core, generally of the kind disclosed by Keller et al. but that is improved thereupon in at least certain resepcts, that is of incomplex and economical construction, that is readily mounted upon and dismounted from printer spindles of various forms, and that enables reliable and stable positioning of the core on the spindle while affording secure support for the inked ribbon wound thereupon. Accordingly, the broad objects of the invention are to provide a ribbon core having the foregoing features and advantages, and a core and spindle assembly utilizing the same.
It has now been found that certain of the foregoing and related objects of the invention are attained by the provision of a spindle-mountable core comprising a tubular body having an outer surface for receiving and supporting a length of web material wound thereupon, and a generally cylindrical inner surface defining a bore through the body for receiving a spindle inserted from the aft end (i.e., the end of the core closet to the printer, as mounted). A plurality of circumferentially spaced ribs extend axially along the bore, and radially inwardly from the inner surface of the body, for slidable engagement in or against corresponding groove structure on the outer surface of a mounting spindle, each rib preferably being of uniform circumferential width along its entire length. Stop means is provided on the core for engaging the spindle, so as to limit the depth of insertion and thereby define a fully mounted position, and collar structure on the inside surface of the body, circumscribing the bore, constitutes an interference band having a contact surface with an effective inside diameter smaller than the diameter of the major portion of the bore. The collar structure is disposed near the fore end of the bore and serves, in the fully mounted core position, to frictionally engage circumferential contact means on the spindle.
The collar structure (and its contact surface) will normally be circumferentially continuous and of substantially uniform radial thickness. The stop means will usually comprise an engagement element operatively disposed between the collar structure and the fore end of the bore, preferably providing a circumferential shoulder disposed radially inwardly of the contact surface of the collar structure and most desirably taking the form of ring structure on the inside surface of the body, effectively circumscribing the bore adjacent the fore end; the ring structure will normally be of substantially uniform radial thickness, greater than the thickness of the collar structure.
Other objects of the invention are attained by the provision of an assembly comprised of an elongate spindle and a web material-supporting core, constructed as herein described. The spindle includes a shaft portion having groove structure (i.e., either a slot defined by two parallel walls, or a single wall) that opens forwardly and radially outwardly, and a forward end portion having circumferentially disposed external contact means thereon. The ribs on the core are slidably engaged in or against the groove structure of the spindle, and the stop means on the core engages the spindle so as to limit the depth of insertion; the collar structure on the inside surface of the body frictionally engages the circumferential contact means on the spindle, for retention of the core in its fully mounted position.
In preferred embodiments of the assembly the groove structure on the spindle defines at least one slot, and at least one of the ribs on the core is dimensioned to frictionally engage corresponding slot-defining structure on the spindle, so as to cooperate with the collar structure and spindle contact means for maintaining the fully mounted position of the core. The ribs will normally be of uniform circumferential width along their entire length, and the groove structure will normally extend through the forward end portion of the spindle, as well as along the shaft portion. Typically, the cooperating rib and slot-defining structure, and the cooperating collar structure and spindle contact means, will function together to provide a holding force of about 4 to 6 pounds for retaining the core against axial displacement on the spindle.
Turning now in detail to the appended drawings, it is seen that the ribbon-supporting core of the present invention consists of a cylindrical body, generally designated by the numeral 10, having a bore 12 extending from end-to-end there-through. The bore is of constant diameter along most of its length, but a short, reduced-diameter axial section, adjacent the fore end of the core, provides an integral collar or interference band 14. A ring-like element 16, contiguous to the fore end of the collar 14, provides a stop for limiting the depth to which a printer spindle can be inserted into the bore 12. Three ribs 18 extend, at equiangularly spaced (120°) circumferential locations, from adjacent the aft end of the body 10 to the stop ring 16; they are of constant width along their entire length.
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An additional component of holding force is generated by engagement of the circumferential contact surface elements 32, which discontinuously (i.e., as arcuate segments) surround the base of the frustoconical leading end portion 22 of the spindle, upon the collar 14 of the core. As will be appreciated, the radial thickness of the collar 14 is such that it grips the circumferential surface elements 32 on the spindle to produce substantial resistance to relative movement, especially under the compressive force of a ribbon would tightly upon the core; indeed, the relative dimensions are such that discernable expansion occurs at the collar when the spindle surface elements bear thereagainst.
The ring-like stop element 16 provides a circumferential edge 17, disposed radially inwardly of the interference band 14, that engages the frustoconical surface 22 of the leading end portion of the spindle (in circular line contact), thereby determining the depth to which the spindle can be inserted into the core. Needless to say, the position and dimensions of the ring-like element 16 are such that inter-engagement occurs when the surface elements 32 bear fully upon the interference band 14.
In a specific embodiment of the invention, the ribbon core is constructed for use in a Monarch 9800 printer (Monarch Marking Systems, Inc.). For that application, the body of the core is about 4.3 inches long and about 1.5 inches in outside diameter, with a bore diameter of about 1.15 inches extending along most of the length of the body. The stop ring is positioned about 0.21 inch from the fore end of the core body, and has an axial length of about 0.12 inch and an inside diameter of about 1.0 inch. The gripping collar extends about 0.4 inch beyond the ring element, to the aft side, and has an inside diameter (in unstressed state) of about 1.12 inch. The ribs on the core body are about 0.13 inch in circumferential width and extend from adjacent the stop ring to a point approximately 0.07 inch from the aft end of the body; the top surfaces of the ribs lie in an imaginary cylinder of about 0.98 inch diameter. Normally, the core will be fabricated from a synthetic resinous material, such as ABS copolymer, nylon, high impact polystyrene, or the like.
It will be appreciated that variations in the form and dimensions of the core of the invention, and of a spindle used in assembly therewith, may be made without departing from the scope of the appended claims. Although the core is intended primarily for use with an inked ribbon roll in a printing machine, it will be appreciated that other web material may be wound upon the core for discharge and take-up, and for other applications, as may be appropriate.
Thus, it can be seen that the present invention provides a novel inked ribbon core, for use with a printing machine, that is of incomplex and economical construction, is readily mounted upon and dismounted from spindles of various forms, and that nevertheless enables reliable and stable positioning on the printer spindle while affording secure support for the ribbon wound thereupon. The invention also provides a novel core/spindle assembly affording such features and advantages.