US2902136A - Ribbon mechanism - Google Patents

Description

w. B. WHIPPO RIBBON MECHANISM Sept. 1, 1959 4 Sheets-Sheet 1 Filed Dec. 20, 1957 INVENTOR. WALTER B. WHIPPO BY 51,

ATTORNEY Sept. 1, 1959 w. B. wHlPPo 9 2,902,136

RIBBON MECHANISM 4 Sheets-Sheet 2 Filed Dec. 20, 1957 Sept. 1, 1959 Filed Dec. 20, 1957 W. B. WHIPPO RIBBON MECHANISM 4,Sheets-Sheet 3 Sept. 1, 1959 w. B. WHIPPO RIBBON MECHANISM.

4 Sheets-Sheet 4 Filed 1360.. 20, 1957 FIG.,5'

United States Patent Ofiice Patented Sept. 1, 1959 RIBBON MECHANISM Walter B. Whippo, Lexington, Ky., assignor to Inter- J national Business Machines Corporation, New York, N.Y., a corporation of New York Application December 20, 1957, Serial No. 704,195

8 Claims. (Cl. 197-165) This invention relates to a ribbon feed mechanism and more particularly to a single feed mechanism operable to drive a pair of ribbon spools alternately.

The usual constructions of typewriter ribbon mechanisms includes a ribbon spool at each side of the typewn'ter, drive mechanism for feeding ribbon from one spool to the other past a printing position and duplicate I mechanisms at each n'bbon spool for reversing the teen when ribbon is exhausted from one spool whereby the exhausted supply spool becomes the driven take-up spool and the take-up spool becomes the supply spool.

This invention is a departure from the conventional structures in that a single feed mechanism serves to drive the two spools alternately and also permits movement of the ribbon feed mechanism along with a movable print element.

Accordingly, a primary object of this invention is to provide an improved ribbon feeding device.

Another object of this invention is to provide a ribbon mechanism adapted for handling ribbon-s on flangeless spools.

A further object of this inventionis to provide a ribbon mechanism adapted for handling a ribbon mounted in a casing on two spools.

Still another object of the invention is to provide an improved reversing mechanism operating to eliminate excess wear of the ribbon at the reversing points thereof. 3 It is another object of this invention to provide a ribbon mechanism which is compact and may be handled as a single complete unit.

Another object of this invention is to provide a ribbon mechanism movable with a print element to successive print positions.

Another object of the invention is to provide a reversing ribbon mechanism in which the reversing takes place during the idle time between print strokes.

Other objects of the invention will be pointed out 1 Figure 4 is a sideelevation of the ribbon mechanism mounted on a carrier.-

Figures 5 and 6 show a ribbon cartridge. Referring to Figure 4, the ribbon mechanism generally designated 10 is mounted on a carrier 12 of the type illustrated in a copending application, Serial Number 653,806, title: Keyboard Selection Mechanism, filed April 19, 1957, on behalf of Leon E. Palmer, for use with a single print element typewriter wherein the platen is stationary and the Single print element is moved 7 across the platen to successive print positions. In the '2 embodiment 'shown herein, the ribbon mechanism moves with the print head across ,the platen; however, the ribbon mechanismcould be stationary for use with a conventional typewriter in which the platen moves to present successive print positions.

As described in the above cited patent application, a shaft 14 is rotated once for each print stroke and operates through -;a cam (not shown) to throw the print head 15 and a ribbon 16 against a platen 17 to effect printing of a character selected by rotation and tilting of the head 15. The same shaft 14 is utilized to operate the ribbon mechanism 10 in a manner described hereinafter. The ribbon mechanism 10 is adapted to receive a cartridge 18 containing two ribbon spools.

Referring to Figures 5 and 6, the ribbon cartridge 18 isshown with two flan'g'eless spools 19. The cartridge 18 may be inade of any suitable material, for example a transparent styrene. 'Ihecartridge comprises an upper wall 18-1, a lower Wallis-2 and a continuous side wall 18-3. The side wall 18-3 contains a pair of ribbon slots 18-4 to accommodate the ribbon 16 which extends from one spool 19 through one slot 18-4, through scribed hereinafter. The spools19 have reduced end portions19-1 which fit rotatably into holes 18-6 in the upper and lower walls of the cartridge 18. The upper and lower ends of each spool 19 contains a centering hole 19-2 and ten equallyspaced holes 19-3 surrounding the hole 19-2.- The slots 18-5 are for mounting the ribbon cartridge -18 on the ribbon mechanism 10 in a manner described hereinafter., The holes 19 2 aid in positioning the cartridge in the ribbon mechanism 10 whereas the holes 19-3 form .a driving connection for the spools in a manner described hereinafter. It will be apparentthat, with holes 18-5, 19-2 and 19-3 'in boththe upper and lower sides of the cartridge and spool combination, the unit is completely reversible, it being immaterial which side of the cartridge is turned up.

A distinctive feature of the cartridge assembly is that there are no'flanges on the spools. The center distance between the spools is less than the full diameter of the ribbon on eachspool. If flanges were provided on the spools, for example, for ratchet teeth the flanges would have to be as large as the full ribbon diameter and the center to center distance would have to be great enough to allow the flanges to clear each other. Since there are no flanges in the preferred embodiment, and only one spool can contain a full diameter of ribbon at a time, it is possible to bring the spool centers closer together. The necessary spacing of the spool centers is such that, with half of the desired quantity of ribbon on each spool, there will be clearance between them.

Referring to Figure 1, the shaft .14 has a cam 20 fixed thereto for operating the ribbon mechanism 10 during each revolution of the shaft. The ribbon mechanism 10 includes a base plate 22 having slots 24 adapted for mounting the ribbon mechanism on the carrier 12 by means of screws 26, shown in Figure 4. The base plate 22 has upturned flanges 27L and 27R adapted for engaging-the holesf18-5 in the upper or lower walls of the cartridge 18 for mounting saidcartridge on the ribbon mechanism. The base plate 22 also has a pair of turned up' fianges 28L' and 28R for use in a manner described hereinafter; A'pa'ir of ribbon tension arms 30L and 30R are pivotally mounted on the base plate 22 by respective studs 32L and 32R. Thegtensionarms 301. and 30R have turned down flanges 34L and 34R, respectively. The tension arms 30L and 30R are connected together by a spring 36 fixed to studs 35L and 35R extending through arcuate slots 37L and 37R in the base plate 22, and the arms are biased by this spring in a counterclockwise and a clockwise direction, respectively. A reversing member 38' is freely mounted on top of the base plate 22 and carries a pair of turned down flanges 40L and 40R which rest adjacent the turned down flanges 34Land 34R of the tension arms. The reversing member 38 also carries a pair of turned up flanges 42L and 42R engaging a spring '44 which is retained in a notch 46L on the tension arm 38L and in a notch 46R on the tension arm 38R. The reversing member 38 is free floating as described hereinbefore'and is retained in position between the flanges 28L, 28R, 34L and 34R by the spring 44.

A pair of ratchet wheels 48L and 48R are rotatably mounted on the base plate 22. Each ratchet wheel carries a spindle 50L and SOR'in the center of the respective ratchet Wheels and a pair of pins 52L and 52R on opposite sides of the respective spindles 50L and 50R. The spindles 50 engage the centering holes 192 of the spools 19 whereas the pins 52 engage the pairs of holes 19-3 to lock the spools 19for rotation with the ratchet wheels 48L and 48R. The holes 193 are sufliciently close together that beveled edges of adjacent holes intersect in a manner whereby the pairs of pins 52 readily engage pairs of holes 19-3 for easy mounting of the cartridge 18 on the ribbon mechanism 10.

A cam follower 54 is oscillatably mounted in a bracket 56 fixed to the carrier 12 by a screw 57. The cam follower 54 is pivotally joined to anindexing pawl 58 by a stud 60. The pawl 58 is mounted in a bracket 62 fixed to the bottom of the base plate 22. The pawl 58 is freely mounted in the bracket 62 by means of a bevelled hole 64 whereby the pawl 58 may pivot about a horizontal axis running parallel to the shaft 14 in response to the movement of the cam follower 54, as well as about a horizontal aXis running at 90 to the shaft 14 as described hereinafter. In Figure 1, the bracket '62 is shown detached and spaced from the base plate 22 for clarity and the pawl 58 is broken.

A detent member 66 is mounted on the base plate 22 by means of a pivot 68 and is connected to the upper end of the pawl 58 by a spring 70. Each revolution of the shaft 14 and the ribbon feed cam 20 eifects an oscillation of the pawl 58 thereby effecting an indexing movement of the ratchet wheel 48L or 48R then engaged by the pawl 58. The detent member 66 engages the driven ratchet wheel 48L or 48R to prevent backward movement thereof. The reversing member 38 has three arms 72L, 72R and 74 on the end opposite the flanges 42L and 42R. The ribbon 16 carries a grommet 76, Figures 2 and 3, near each end of the ribbon, adapted to actuate the ribbon tension arms 36L and 30R. When the ribbon is exhausted, for example, from the spool 19 on the ratchet wheel 48R, as indicated in Figure 2, the grommet 76 in the ribbon 16 passing through an open end slot 77R, Figure 1, engages the ribbon tension arm 30R and, as the ribbon continues to feed onto the left hand spool 19, the arm 30R is pivoted counterclockwise about its pivot 32R as shown in Figure 2. As the arm 30R pivots counterclockwise, the flange 34R moves away from the flange 40R of the reversing member 38 and the tension of the spring 44, increased by the counterclockwise rotation of the ribbon guide 30R to which the right end of the spring 44 is fixed, draws the reversing member 38 in a clockwise direction about a pivot point formed at the flanges 34L and 40L. The right hand arm 72R of the member 38 swings to the left and moves behind an upturned flange 78R formed on the detent member 66. At the same time the arm 74 moves to the left and is interposed in the path of oscillation of the pawl 58 as shown in Figure 2. If the pawl 58 is in its advaned position at the time the arm 74 swings to the left, the arm 74 rests against the side of the pawl 58 until the pawl 58 is retracted at which time the arm 74 is interposed as described.

As shown in Figure 2., there is a component of force of the spring holding the pawl 58 in engagement with the ratchet wheel 48L. At the next forward movement of the pawl 58, the pawl advances the wheel 48L as before, but also engages the end of the arm 74, driving the reversing member 38 ahead of it. As the member 38 is driven back toward its normal position, a surface 79R on the arm 72R engages the upturned flange 78R on the detent member 66, thereby pivoting the member 66 in a counterclockwise direction. The detent member is driven against increasing tension of the spring 70 until such time as the spring 70 crosses the pivot point 68 (see dotted outline in Figure 3), at which time, the tension of the spring 70 then acts to snap the detent member 66 into engagement with the ratchet wheel 48R and to snap the pawl 58 to the right pivoting it about the horizontal axis referred to hereinbefore whereby it will engage the ratchet wheel 48R. The driving engagement of the pawl 58 with the ratchet wheel 48L is suflicient to maintain the pawl 58 to the left as shown in dotted outline in Figure 3, as the leftward component of force of the spring 70 diminishes and then becomes a rightward force, until after the spring 70* crosses the pivot point 68. At the end of the power stroke of the pawl 58 when the driving engagement is released, the pawl 58 snaps over to the ratchet wheel 48R. As the pawl 58 and the detent member 66 are both removed from engagement with the ratchet wheel 48L, the wheel 48L and the left hand spool 19 are free to rotate thereby relieving the tension of the ribbon 16 and permitting the ribbon tension arm 30R to return to its normal position and restore the reversing member 38 to its normal position. It will be noted that the complete reversal of the ribbon feed pawl 58 has taken place during the idle time between feed strokes.

One of the drawbacks to the conventional reversible ribbon feed mechanisms is that the last used pointon each end of the ribbon is subjected to more wear than the intermediate points, due to the sluggish operation of those mechanisms, resulting in holes being worn at those end points. The life of the ribbon therefore is limited by the life of the end points, which is shorter than the useful life of the remainder of the ribbon. The ribbon mechanism illustrated and described herein permits only one print stroke at the end points of the ribbon thereby subjecting the end points to actually less wear than the intermediate points of the ribbon and prolonging the useful life of the ribbon. This also reduces operating costs due to additional ribbons and time required to change ribbons.

The pawl 58 will step the ratchet wheel 48R in a winding direction during each rotation of the cam 20 until the spool 19 on the ratchet 'wheel 48L is exhausted, at which time, an operation similar to that described hereinbefore will take place to return the pawl 58 from the wheel 48R to the wheel 48L. 'In'this operation, the ribbon tension arm 30L'is pivoted clockwise permitting the reversing member 38 to pivot about a point formed by the flanges 34R and 40R to swing the arm'72L behind the lug 78L whereby the next oscillation of the pawl 58 will drive the reversing member 38 causing the detent member 66 to flip to the wheel 48L and draw the pawl 58 also to the wheel 48L.

It will be apparent that this invention may be practiced without departing from the spirit of the invention, by using ribbon spools, either in or out of a cartridge, having toothed flanges rather than by mounting flangeless spools on the illustrated ratchet wheels, or by using flangeless spools without the cartridge.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood hat variousomissions and substitutions and changes '5 in the form and details ofthe device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore, .to be limited only as indicated by the following claims. v

What is claimed is: a I 1 1. In a ribbon feeding device, in combination, a ribbon, a pair of spools alternately serving as supply and takeup spools for said ribbon, an indexing element movable alternately to two driving positions and recip-rocable in said. positions for driving one or the other of said spools, the driven spool acting as the take-up spool and the other as the supply spool, toggle means biasing said indexing element to the driven one of said spols, ribbon tension means operable when ribbon is exhausted from said supply spool for actuating said toggle means to move said indexing element from said driven spol to said exhausted supply spool, means for reciprocating said indexing element, a detent associated with said toggle means and operative for restraining the driven one of said spools against backward movement during reciprocation of said indexing element, said toggle actuating means being operable to move said detent with said indexing element from one spool to the other.

2. In a ribbon feeding device, in combination, a ribbon, a pair of spools alternately serving as supply and take-up spools for said ribbon, a reciprocable indexing element movable alternately to two driving positions and reciprocable in each of said positions for driving one or the other of said spools, the driven spool acting as the take-up spool and the other as the supply spool, toggle means biasing said indexing element to the driven one of said spools, ribbon tension means operable when ribbon is exhausted from said supply spool, interposer means movable by said tension means into the path of reciprocation of said indexing element and operable by said indexing element for actuating said toggle means to move said indexing element from said driven spool to said exhausted supply spool, and means for reciprocating said indexing element.

3. The invention of claim 2 wherein said toggle means includes a detent member operative in one position to restrain the driven spool against backward movement and engageable by said interposer means for movement to another position wherein said detent element restrains the other said spool and biases said indexing element to said other spool.

4. In a ribbon feeding device, in combination, a ribbon, a pair of flangeless spools, a pair of ratchet wheels for mounting said spools, an indexing element alternately engageable with said ratchet wheels for driving one or the other of said spools, toggle means biasing said indexing element to engagement with one of said ratchet wheels and including a detent element engageable with the driven ratchet wheel and a spring connecting said detent element with said indexing element, ribbon tension means associated with each of said spools and operable when ribbon is exhausted from the associated spool, interposer means movable selectively by the operated ribbon tension means into the path of reciprocation of said indexing element and operable by said indexing element for moving said detent element into engagement with the other ratchet wheel, in which position said connecting spring biases said indexing element to engagement with said other ratchet wheel, and means for reciprocating said indexing element.

5. In a ribbon feeding device, in combination, a ribbon, a pair of ratchet wheels, a casing rotatably mounting a pair of flangeless ribbon spools, means for operatively connecting said spools and said ratchet wheels, an indexing element alternately engageable with said ratchet wheels for driving one or the other of said spools, toggle means biasing said indexing element to engagement with one of said ratchet wheels and including a detent element engageable with the driven ratchet wheel and a spring connecting said detent element with said indexing element, ribbons tension means associated witheach ofsaid spools and operable whenyribbon is exhausted from the associated spool, interposer means movable selectively by the operated ribbontension means into the path of reciprocation of said indexing'element' and operable by said indexing element for-moving said detent element into engagement with the other'ratchet wheel,- in which position said connecting spring biases said indexing element to engagement with said other ratchet wheel, andfmeans for reciprocating said indexing elementar 6. In a ribbon feeding device, in combination, a ribbon, a pair of flangeless spools, a pair of ratchet wheels for mounting said spools, an indexing element alternately engageable with said ratchet wheels for driving one or the other of said spools, toggle means biasing said indexing element to engagement with one of said ratchet wheels and including a detent element engageable with the driven ratchet wheel and a spring connecting said detent element with said indexing element, ribbon tension means associated with each of said spools and operable when ribbon is exhausted from the associated spool, a constraining spring, interposer means constrained against said ribbon tension means by the last said spring and shiftable by the last said spring in accordance with the operated one of said ribbon tension means to be interposed in the path of reciprocation of said indexing element and operable by said indexing element for moving said detent element into engagement with the other ratchet wheel, in which position said connecting spring biases said indexing element to engagement with said other ratchet wheel, and means for reciprocating said indexing element.

7. In a printing device, a ribbon feed mechanism comprising, in combination, a base plate, a pair of ratchet wheels rotatably mounted on said plate, a pair of ribbon spools engageable with said ratchet wheels for rotation therewith, said spools serving alternately as supply and take-up spools, a pair of ribbon tension arms pivotally mounted on said plate and biased one toward the other by a spring, each said tension arm being pivotable in response to exhaustion of ribbon from a corresponding spool, a reciprocable indexing member pivotally mounted on said plate and movable to driving position relative to said ratchet wheels alternately, a detent member pivotally mounted on said plate for engagement with the driven one of said ratchet wheels and having a pair of operating lugs, a spring interconnecting said detent member and said indexing member and operative to bias said indexing member to said driving position corresponding to said ratchet wheel engaged by said detent member, a constraining spring, a reversing member constrained against said ribbon tension arms by the last said spring, said reversing member including a pair of arms each engageable with one of said operating lugs on said detent member and an interposer arm movable into the path of reciprocation of said indexing member, said reversing member being operable by said constraining spring when one of said ribbon tension arms is pivoted, said reversible member operating on one of said lugs to pivot said detent member into engagement with the ratchet wheel mounting said exhausted spool, said detent member thereafter operating through said interconnecting spring to move said indexing member to engagement with the last said ratchet Wheel, and a rotatable cam and a cam follower operatively connected to said indexing member for reciprocating the latter.

8. A mechanism for feeding ribbon past a single element type head mounted on a carrier which is movable along a platen to successive print positions comprising, in combination, a base plate fixed to said carrier, a pair of spindles rotatably supported at one end by said base plate, a ratchet wheel fixed to each of said spindles adjacent said base plate, a ribbon casing, means for mounting said casing on said base plate in a position overlying said ratchet wheels, a pair of tubular shaped spool members extending through said casing and rotatably supported at their ends in the upper and lower walls of said casing, said spool members opening through said upper and lower casing walls and adapted to receive said spindles, means attaching said spool members to said ratchet wheels for rotation therewith when said casing is mounted on said base plate, said ribbon being wound at its ends upon said spool members and adapted to be fed from one to the other upon selectively driving said ratchet wheels, openings in the side of said casing through which said ribbon passes as it is fed from one of said spool members to the other, means including an element en- References Cited in the file of this patent UNITED STAT-ES PATENTS 1,937,145 Gollwitzer Nov. 28, 1933 FOREIGN PATENTS Germany Nov. 4, 1939

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