US2505991A

US2505991A - Ribbon feed device

Info

Publication number: US2505991A
Application number: US673546A
Authority: US
Inventors: Leonhard F Reinhold
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1946-05-31
Filing date: 1946-05-31
Publication date: 1950-05-02
Anticipated expiration: 1967-05-02

Description

May 2, 1950 L. F. REINHOLD RIBBON FEED DEVICE Filed May 31, 1946 I INVENTOR LEO/VHARD ERE/Nww ATTORNEY Patented May 2, 1950 RIBBON FEED DEVICE Leonhard F. Reinhold, Great Kills, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application May 31, 1946, Serial No. 673,546

7 Claims. (Cl. 197-162) This invention relates to typewriter ribbon feed devices and, more particularly, to an arrangement for controlling a typewriter ribbon such as called for in the operation of telegraph typewriters and typewriting machines which comprise a type wheel.

It is an object of my invention to provide an improved ribbon feed mechanism for a telegraph typewriter such that the ribbon spools when requiring reversal of their motions will be reversed in operation by means of a simple mechanism that is also readily actuated from a rotating cam.

It is another object of my invention to provicle a transfer mechanism operable, whenever either of the ribbon spools becomes unwound, to engage a driving pawl with an associated ratchet wheel for causing that particular spool to start re-winding the ribbon.

My invention will now be described in more detail, reference being made to the accompanying drawing, the sole figure of which represents diagrammatically a combination of mechanical elements which are essential to the carrying out of the invention.

Referring to the drawing, I show therein two shafts I which respectively carry the ribbon spools la and lb, and ratchet wheels by which either one of the spools is driven to wind up the ribbon, the other spool being free to pay out the ribbon. The ratchet wheels are driven by a pawl member 2| which is arranged to have a toggle action so that it bears against either one or the .other of the two ratchet wheels. The pawl member 2| is a portion of a toggle-acting member Ill which is swiveled on a pivot pin |3 carried by a t draw-bar 9. The draw-bar is held in position at its upper end by a stationary pin extending -.through a slot |'|a in the draw-bar. At the lower end of the draw-bar 9 is a pivot pin 1 by which ,linkage is efiected with an operating lever 5.

Lever 5 is pivoted at 6 and the left hand end is provided with a roller 5a which bears against the periphery of a cam 8a. This cam is driven counter-clockwise on a shaft 8, single revolutions .being made in a start-stop manner after each operation of a printing platen 29. The ink ribbon 24 and record tape 28 are both fed between the platen 29 and a typewheel 25a.

The typewheel rotates on a shaft 25, the indexing motion of which it is unnecessary to describe since it forms no part of the instant invention.

The ink ribbon 24 is wound on spools la and lb and is guided by guide rollers IS in front of the typewheel 25a. The record tape 28 is trained 2 over two

rollers

26 and 30, and is guided by members 27 between the ink ribbon and the printing platen 29.

Obviously, the striking of the printing platen 29 against the record tape exerts pressure between this platen and the typewheel, and an ink impression of the opposed type character is thus formed on the record tape.

The draw-bar 9 is pulled upwardly by tension of a spring l8. This tension also tends to engage the roller 5a on the lever arm 5 against the periphery of the cam So. When the hump of the cam raises the roller 5a the consequent rocking action of the lever 5 draws the pawl 2| downwardly and turns the ratchet wheel through an arc of one tooth space. Then the ratchet wheel is retained by a retaining pawl member M which is pivoted at I6 and held against the ratchet wheel by means of a spring Ma.

When the ratchet wheel la is being driven in the manner above described, the ratchet wheel lb is free to permit unwinding of the ink ribbon because its associated retaining pawl It is held out of engagement. Each of the pawls M is provided with a pin l5 resting upon the edge of an upwardly extending arm 22 that is formed integrally with the member Ill. A spring 23 is anchored at its two ends by pins II and I2, pin being mounted on the driving pawl 2| and pin [2 being mounted on the draw-bar 9. Since the two pins I and I2 are on opposite sides of the pivot pin l3 the spring 23 operates to hold the pawl member 2| either on one side or the other until its position is reversed by the action of one or the other of two lever members 2a and 2b.

The two bellcrank levers 2a and 2b are mounted respectively on one and the other of two pivot pins 3 and are normally held by springs 28 so as to exert a slight pressure of their rollers 4a and 41) against the ribbon for maintaining the ribbon taut. When, however, the ribbon is completely unwound from one of the spools it tends to rotate the lever members 2a and 2bin such a man her as to exert pressure on the nearer one'of the two side arms of the member It. This action causes the lever In to swing to the other side where the pins IE on the retaining pawl-s M are moved into a new position and the retaining pawl which was previously relieved from duty is now engaged with its ratchet Wheel, while the previously engaged pawl is drawn away from its ratchet wheel. In this manner the next operation of the driving pawl 2| is such as to produce a reverse action on the winding of the ink ribbon.

A feature of the design that is worthy of note is the fact that when the toggle member ID is in the position shown in the drawing the outer edge of the right-hand arm 22 lies parallel to the direction of motion of the draw-bar 9. Hence the downward movement of the draw-bar and toggle member has no effect upon the position of clearance between the right-hand retaining pawl and the ratchet wheel 111. On the left side of thetoggle member the inclinationlof the outer edge of the arm 22 with respect to the axis of the draw-bar 9 is such that a space betweenit and the pin IE (to the left) is opened up and the retaining pawl I l cannot be lifted out of engagement with its associated ratchet ;wheel la until after the next ribbon feedreversaltakes-placein accompaniment with the toggle action of member III. of course, when the toggle .memberleans the other way from that shewn' in the drawing then the left hand and right hand ccnditionsiset forth in this paragraph are reversed.

Another feature of the invention: relates j to the unequal :angles made :by the directions of travel of the ribbon 24 as it passes over the rollers 4a .;;a-nd s4b,;r.espectively,watthetime of performing the 1 automatic reversing .function. When the isspool la'is fully woundthe angle at roller 44: is :considerable-whereas .the angle at roller 4b is very slight due to the ,fact that spool 1b is com- :ip'letelynnwound. The anchorage of the ribbon endsbnthetwo spools makes the ribbon taut .-vwhe'n,one of-the spools becomes-completely unwound. The greater angle-of deflectionatroller 4a :enablesethe ribbon to .eXert .a considerable 'pressurethereoniso asito rotateithe lever 2a "'clockwise -for actuating .the toggle member ID. Onthefight hand side,'however, the angle .of deflection of themibbon-at roller 2b is so slight (due 'to th e' tension of spring 28) that substantiallyno movement of the lever takes place. "Still-anotherfeature of the invention-resides in*i'ts freedom from adverse influences "in case .of :shock. It is contemplated that -the type- "writingmachinewith which my ribbon feed and ribbon reversing-device may be associated might *beflcarried aboardan airplane or other moving vehicle. Incase of sudden shock to which the ,japparatus may be subjected'it is "conceivable'that 1. a 'su'ddengchangein the direction of motion of lithervehiclemight cause the toggle member i .lto he thrown from one sideito the other. The lonlylresult ofithislaction would be to reverse the directionIofribbonieed'before onev of the spools lhadlbecome completely unwound. Obviously, in this lease the retaining pawls l4 would assume their. appropriate positions .for maintaining the ,direction.of'ribbonfeed as then in effect and until' the-next normally produced reversing oper- ,.ation-itook place.

,It will be understood bythose skilled in the art :that various modifications .of my invention may be;made without departing from its spirit vand scope.

:Iclaim:

'1. .-A typewriter .ribbon feed device having two .windingspools for .the ribbon, ratchet wheels co- -,axially'mounted with respect to said spools, a spring tensionedtoggle member, anintegral portion :of which is constituted as two engaging pawls,-.-,each one ofwhich is engageable with one of said ratchetwheels at .a time, two retaining ipawlseach alternately ,engageable with a respec- ,tive ratchet wheel, means including a cam-operated lever. system for producing tangential .mo- ,-tion ofione of the engaging pawls with, respect 4 to the ratchet wheel with which it is engaged, thereby to cause a winding up of the ribbon on the spool associated with that ratchet wheel, and ribbon-controlled mechanism for releasing the retaining pawl from engagement with the other ratchet wheel to permit the other ratchet wheel to pay out the ribbon and for causing said .togglemember to shift-.the;.oth er of ,said engag- Ling' ,pawls to the other ratchet wheel inLresponse to an increase in ribbon tension.

2. A typewriter ribbon feed device having two winding spools for the ribbon, ratchet wheels coaxially mounted with respect to said spools a retaining pawl for each ratchet wheel, a spring itensioned toggle member having an integral portiomthereofconstituted as a two-pronged engaging pawl, .a draw-bar providing support for "said toggle member and movable longitudinally alongyan'axis which bisects and is perpendicular to a line of interconnection between the axes cfsaidspools,astationary pinextending through a slot in said drawharder .iib tioiiing ,the upper -.end=thereoi,a springior retracting said draw-bar upwardly, a carnecontrolledjleyer'for positioning ,said draw-bar at lits lower end ..and.;forf actuating the same, and a ribbon controlled mechanism-ineluding .-a roller :which .is in ,contact .with the ribbonior causing said toggle linember .to .shift its pawl from one toj'the other of .its alternate positions of engagement with .tlie respective ratchet Wheels.

.3. A;typewriter ribbon feeddeviceil' ayingtwo winding spools forthe ribbon,f.ratchet wheelscoaxially .mounted with respect to said ljsp'ools, .a retaining ,-pa w1 for each ratchet wheel. ,a spring tensioned; toggle member having amintegral portion thereofi constituted asa two pronged' engaging pawl, a draw-bar providing supportgforl'saiui toggle :member and movable dongitudinally along an vaxis which bisects ,and .isperpendi uIarlO ,a line ,of inter-connection between the axes of said spools, a stationary pin-extending through. aslot .in said drawbar. for, positioning the upper ,end thereof, a spring for retracting ,fsaid nraw-bar upwardly, a-icam-controlled lever ,for positioning said draw-bar at itsi lower-en d and;for actuating the same, and means including a .rib bon controlledlmechanism for causingjsaid toggle member to alternately shift its l-pa wl including gave bell-crank levers ,;,a,dapted arranged ,toibe selectivelyactuated by theribbon in dependence upon the relativeangles; of deflection offsaid ribbon-at points of. contact -.-ther eof, with one, and the otherrespectively ,of two-rpllerseach. mounted on :arespective bellecranle lever.

,4, In ,a typewriter ribbon feed mechanism, two ribbon .spools and associated. .ratchet 7 wheels, ,a two-pronged drivingpawl alternatively engageable with one and ,the other of .said\-ratchet wheels, said pawl being constituted aslan-cxten- *sion from a,,toggle-acting. member, tensional means for tilting said member 'to,.one., side..or the ;other, i thereby to engage its -.-p3rW1. ,wi-th a, given ratchet wheel, cam-controlled means. fonreciproeating,- said pawl tangenunwwnn respect to h ratchetwheel with which. disengaged, a, pivoted retainingpawl for each ,ratchetjwheel and means operable by said togglesaoting member fonholdingan appropriate one of said [retaining pawls in a, position lof disengagement from its ratchet wheel for. permitting jpayout, of, ribbon from ,the associated spool. o

,5. The ,device according, to .claim ,4 and including ,an j. automatic feed, reversing device operable iniresp'onse lto an increase inlir'ibbon tensionfbe tween its two spools for controlling said toggleacting member thereby to shift the engagement of said driving pawl from one to the other ratchet wheel.

6. In a device for reversing the direction of feed of a typewriter ribbon, two spools having ribbon anchoring means at their cores, a ratchet wheel for each spool, reciprocating means including a spring tensioned toggle member forming a two-pronged driving pawl for selectively engaging with a single one of said ratchet wheels to turn the same with its spool and thus to wind up the ribbon, two bell crank levers each of which carries a roller for engagement with said ribbon, other rollers mounted on stationary pivots and serving to guide said ribbon in directions such that the ribbon is variably deflected by said lever-carried rollers, and means mechanically linking an appropriate one of the bell crank levers to said driving pawl and operable to shift said pawl from one to the other of, its ratchet wheel engaging positions, the greater deflection of the ribbon on the side of the full wound spool being determinative of a relatively greater vector value of force applied to the bell crank lever v on the operating side due to tightening of the ribbon when its spool on the other side becomes fully unwound.

7. A typewriter ribbon feed mechanism comprising two ribbon spools with associated ratchet wheels attached thereto, a pivoted spring tensioned toggle member having engaging pawls to bear against either one or the other 01 said ratchet wheels, said pivoted spring tensioned toggle member also having upwardly extending arms associated therewith, a draw bar having supporting means for said pivoted spring tensioned toggle member, two retaining pawls each positioned between one of said ratchet wheels and one of the extending arms of said toggle member, a sprin for retracting said draw bar upwardly, a cam control lever linked to said draw bar at its lower end for actuating the same, and means including a ribbon controlled mechanism with two pivoted rollers, each roller being in contact with the ribbon, for causing said toggle mem her to shift the engaging and retaining pawls from one to the other of their alternative positions of engagement with the respective ratchet wheels.

LEONHARD F. REINHOLD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 917,803 Scott Apr. 13, 1909 1,082,774 Sohm Dec. 30, 1913 1,397,895 McCabe Nov. 22, 1921 1,980,723 Hartley Nov. 13, 1934 2,090,811 Salmon Aug. 24, 1937 2,229,397 Thomas Jan. 21, 1941 FOREIGN PATENTS Number Country Date 184,042 Germany of 1907 477,292 Great Britain f 01- 1837 682,804 Germany of 1939