US 3409113 A
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Nov. 5, 1968 R. H. MCLEAN 3,409Q113 RIBBON FEEDING MECHANISM Filed March 16, 1966 2 Sheets-Sheet l Y CLUTCH INVENTOR RONALD H. LEA
33D BY C ATTORNEYS R. H. MCLEAN Nov. 5, 1968 RIBBON FEEDING MECHANISM 2 Sheets-Sheet 2 Filed March 16, 1966 INVENTOF? RONALD H. MCLEAN BY mm ATTORNEYS United States Patent O 3,409,113 RIBBON FEEDING MECHANISM Ronald H. McLean, Newington, Conn., assiguor to Litton Business Systems, Inc., a corporation of New York Filed Mar. 16, 1966, Ser. No. 534,808 2 Claims. (Cl. 197-151) ABSTRACT F THE DISCLOSURE In a typewriter ribbon feed mechanism, a slip drive having a plurality of cantilever mounted arcuately shaped ngers extending radially in the same circular plane from hands symmetrically disposed around the circumference of a iirst hub which is positively driven, to frictionally engage a second hub, the fingers rotating the second hub with the first hub and slipping -in response to load on the second hub.
This invention relates to a ribbon feeding mechanism for a carbon ribbon and more particularly to a mechanism for tightly winding the ribbon onto a take-up spool, and more specically to a mechanism for permitting the ribbon take-up spool to slip with respect to a take-up spool driving member when the ribbon is not being fed.
Carbon ribbon is being increasingly used on correspondence typewriters because of the excellence and clarity of the copy produced thereby. Unfortunately, this type of ribbon may only be used once, and therefore it is desirable that the take-up spool accommodate at least all of the ribbon being ldispensed from the supply spool so as to minimize the number of disposals of used ribbon from the take-up spool. To accomplish this objective with a take-up spool of similar dimension as the supply spool, the run of the carbon ribbon between the ribbon index rollers and the take-up spool must be maintained under tension thereby to wind the ribbon as tightly as possible on the take-up spool. Moreover, since the take-up spool may be driven through a larger angle than that of the ribbon feed rollers, pursuant to the changing diameter of the take-up spool as the used ribbon is wound thereon, a means for slipping the take-up spool with respect to its drive must be provided to maintain the tension and still prevent tearing of the ribbon.
In accordance with the invention there is provided a slip drive characterized by a plurality of cantilever mounted arcuately shaped fingers which lie in one and the same circular plane. The fingers may be integrally supported within a housing hub of a driving member and adapted to couple to an engaging hub on a take-up spool or alternatively the ngers may be integrally supported within a housing hub of the take-up spool, and in this event an engaging hub would be formed on the driving member. In either case, the hub and lingers form a releasably securing drive which permits the take-up spool to rotate when the ribbon index rollers feed the ribbon and to slip with respect to the rotating drive member whenever the index rollers are not feeding ribbon.
Accordingly an object of the invention is in the provision of a s'lip drive which permits uniform feeding and tight winding of ribbon on a take-up spool.
Anot'her object of the invention is to provide a drive for rotating a ribbon take-up spool only when the ribbon is being advanced.
Still another object of the invention is in the provision of a slip drive which permits slip between a take-up spool and the take-up spool driving member.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following ice detailed description when considered in connection with the accompanying drawing in which like reference numerals designate like parts through out the gures thereof and wherein:
FIGURE l is a fragmentary front elevation showing a carbon ribbon supply and take-up spool operatively mounted to portions of the frame of a typewriter;
yFIGURE 2 is an outside left elevation of the carbon ribbon take-up spool, the ribbon index Wheels, and the gear train for driving the index wheels;
FIGURE 3 is a fragmentary elevational View showing the slip drive;
FIGURE 4 is a fragmentary elevational View similar to FIGURE 3 showing the slip drive engaged with the take-up spool hub; and
FIGURE 5 is a fragmentary sectional View taken along line 5 5 of FIGURE 4 showing the slip drive and takeup spool assembly on a frame mounted spindle.
Referring now to the `drawing wherein like reference numerals designate like or corresponding elements throughout the several views and wherein a preferred embodiment is illustrated, there is shown in FIGURE 1 a typewriter frame 10 which rotatably supports on the right side of the machine a carbon ribbon supply spool 11 associated `with conventional drag means (not shown), which prevents too rapid turning of the spool. A ribbon 12 from the supply spool is directed around a right guide roller 13, through a ribbon vibrator structure generally designated by reference numeral 14 and around a left guide roller 1S. As viewed in FIGURE 2, the ribbon after passing around the left guide roller, shown in FIGURE l, passes between ribbon indexing rollers 16 and 17, which normally grip the ribbon and permit a predetermined amount of ribbon to be drawn from the supply spool 11 during each type stroke. More particularly, the roller 16 is supported for rotation on a bracket (not shown), which is spring biased toward roller 17, and roller 17 is rotatably mounted on a shaft 18 and indexable on each type stroke, whereby the ribbon is permitted to be drawn between the rollers and wound on a take-up spool 27 whenever roller 17 is indexed. The roller 17 is integrally formed with an indexing roller drive gear 41, which forms a part of a gear train, generally designated by reference numeral 19, and comprised of a pinion 33 driving a pair of identical intermediate gears 39 and 40, which in turn drive the roller drive gear 41 (FIGURE 2). Pinion 33 is integrally formed with a take-up spool gear 28, which is driven by a drive gear 20 mounted to rotate with a shaft 21 (FIGURE l) when a clutch 22 is actuated on each type stroke, by a conventional mechanism well known in the art, thereby coupling shaft 21 to a constantly rotating power shaft 23. Thus, the indexing roller 17 provides a uniform ribbon feed on each type stroke, and inasmuch as the take-up spool diameter is constantly increasing as the used ribbon is wound thereon, and it is desirable to maintain a length of ribbon 24 taut between the index rollers and the take-up spool, the ratio of gear train 19`is designed to drive the index roller 17 through a much smaller angle than the angle through which the take-up spool gear is driven. Consequently, a slip drive, generally designated by reference numeral 34, must be provided to permit the take-up spool to slip, with respect to the rotating take-up spool drive gear, thereby maintaining the ribbon taut at all times, as will be described below.
Referring now to FIGURES 3 through 5 which best show the structural details of the invention, the take-up spool gear 28 is preferably made of plastic and comprised of an inner hollow hub 30, supported by webs 29, drive gear teeth 32, the pinion 33 and the slip drive 34. Pinion 33 is concentric with hub 30 and supported therefrom on a protruding rear face 30a by three hands 33a., 33b and 3 33e symmetrically disposed around the circumference of the inner hub (FIGURE 3). The slip drive 34 is housed within the hollow hub 30 and includes three arcuate fingers 35, 36 and 37 respectively, which are located in one and the same radial plane within the hollow hub, and are each integrally formed and supported at one end by one of the pinion supporting hands. The unsupported end portions 35a, 36a and 37a of the fingers are formed such that they will engage and be expanded outwardly toward the wall 30h of hollow hub 30 when a protruding hub 27a of the take-up spool 27 is inserted into the hollow hub 30 (FIGURES 4 and 5). Consequently, the takeup spool is frictionally coupled to the yfingers and rotates in synchronism with take-up spool gear 28, on a frame mounted spindle 48, as long as there is no load imposed on the take-up spool. However, whenever the index rollers grip the ribbon, a load is produced which is transmitted to the take-up spool and causes the spool to slip with respect to the rotating take-up spool drive gear, which rotates through a greater angular distance than the index roller, as hereinbefore described.
Since the ribbon is being urged in the wind direction, the length 24 of ribbon between the indexing roller and the take-up spool (FIGURE 2) will be maintained in a relatively taut condition. Furthermore, a brake or no-back assembly -43 prevents the take-up spool gear from rotating in the reverse or clockwise direction, as viewed in FIG- URE 2, thereby sustaining the length 24 of ribbon taut. Brake assembly 43 is comprised of an arm. 42 pivotally mounted to the machine frame by Imeans of a boss 47 and a stud 44. A spring 45 secured to the lower end 42b of the arm and to a frame supported stud 46 biases the upper end 42a of arm 42 into engaging outer ring 31 of the take-up spool. The upper arm end 42a has an arcuate shape which is eccentric with respect to the pivotal mounting of arm 42 whereby the take-up spool gear is free to rotate in a counterclockwise direction and prevented from rotating in a clockwise direction.
The take-up spool 27 may be any conventionally shaped spool consisting of two end flanges separated by a hub for accommodating the ribbon, provided one of the flanges has a protruding hub for engaging the slip drive. Thus, for example, the spool may be similar to that disclosed in copending patent application Ser. No. 461,653, led Ilune 7, 1965, by Carl A. Geissler, now Patent No. 3,317,155 issued May 2, 196'7, except the grooved pulley 24 described in the reference application must be replaced with a hub similar to hub 27a of this application. It is, of course, axiomatic that one of the ribbon spool flanges may be formed to house the integral slip drive instead of the drive gear, in which case the take-up spool gear would have a hub for engaging the slip drive.
It will now appear that I have provided a slip drive that attains the several objects set forth above in a thoroughly practical and eicient manner.
The invention claimed is:
1. In a typewriter having, a carbon ribbon supply spool,
a ribbon vibrator,
a pair of ribbon feed rollers for indexing the ribbon upon each typing stroke,
ribbon take-up means including a drive gear member and a take-up spool member each of which has a hollow hub concentrically mounted for rotation,
a drive shaft operable on each type stroke to rotate said drive gear member,
and a gear train coupled to said drive gear member and said feed rollers to drive said feed rollers through a smaller angle than the angle said drive gear member rotates on each stroke,
the improvement comprising,
a slip drive having releasable securing means integrally formed and housed within the hollow hub of one of said members, said releasable securing means including a plurality of cantilever mounted arcuately shaped ngers extending radially in the same circular plane from one of a plurality of hands symmetrically disposed around the circumference of said hollow hub housing said releasable securing means to frictionally engage the hub of the other member, whereby said releasable securing means will rotate said take-up spool member with said drive gear member and slip in response to load on said takealp spool member.
2. A mechanism as recited in claim 1 including a braking assembly comprising a pivotally mounted arm having an arcuate end eccentrically formed to frictionally engage said take-up spool member and thereby prevent said take-up spool member from rotating in any direction other than a wind direction, and a spring means connected to said arm for biasing said arcuate end into engagement with said takeaup spool member.
References Cited UNITED STATES PATENTS 851,988 4/1907 Howell 197-175 X 871,373 ll/l907 Sponsel 197-151 2,811,235 10/1957 Geissler 197--151 X 3,120,177 2/1964 Clark 197-175 X 3,176,819 4/1965 Bloom et al 197-133 ROBERT E. PULFREY Primary Examiner.
ERNEST T. WRIGHT, Assistant Examiner.