US2238518A - Ribbon spool drive for typewriting machines - Google Patents

Description

April 5 1- w. DIECKM 2,238,518

RIBBON SPOOL DRIVE FOR TYPEWRITING ll ACHINES Filed Oct. 14, 1940 Meta/L BM attozw Patented Apr. 15, 1941 Walter Dieck, Eri'nrt, Germany, assignor to Olympia Biiromaschinenwerke A. G., Erfnrt, Cermany, a corporation of Germany Application October 14, 1940, Serial No. 361,162 In Germany October 6, 1939 2 Claims.

The invention relates to an arrangement for advancing the ribbon of typewriting machines in which the ribbon in the printing position is highly deflected out of its path of longitudinal movement. Such deflection occurs, for example, with machines having an inclined type bar segment, level ribbon spools, and a ribbon shift arrangement, especially in typewriters of low and flat construction.

Usually the portion of the ribbon between the spools is carried closely before the typing cylinder in a ribbon vibrator, the direction of motion of which corresponds to the inclination of the type bar segment and which is in the restin position below the printing position at about the same height as the ribbon spools, one spool, the winding spool, is positively driven, while the other, the unwinding spool, runs as required by the pull of the advancing ribbon.

With typewriters of flat construction, naturally the arrangement of the machine parts is compressed, as far as possible, in height. The segment with the vibrator mounting therefore lies, even though it is already in inclined position, relatively higher than the ribbon spools, because of which the ribbon must be pulled considerably out of its path at the striking point. This displacement occurs most strongly in the uppermost position of the vibrator, that is, on shifting to the uppermost zone of the ribbon, the "red shift, as well as upon shifting the paper vibrator to its raised position for typing capitals, and causes, in combination with the upright position of the ribbon vibrator, a momentary cramping of the ribbon in the repeateddisplacement of the ribbon vibrator head.

The lifting of the ribbon vibrator, therefore also the cramping of the ribbon, occurs simultaneously with the ribbon advancement so that the excessive tensioning of the ribbon at the winding-up side is not responded to by an immediate supply of ribbon from the unwinding spool, which has a retarding effect on the operating bar of the ribbon vibrator and causes it to spring or deflect, since for many reasons it is only weakly made. The consequence of this is a too short advance of the ribbon and thereby.

an unsightly two-colored type impression.

A further disadvantage is connected with this condition since the advancement of the ribbon is brought about by the pushing down of the key levers which raise the type bars. A binding of the ribbon advancement, and thereby of the ribbon vibrator movement, entails therefore a braking of the type bar operation so that in order to overcome this resistance a stronger, undesirable increase in strain of the blow on the keys is required.

These dimculties are eliminated in the present invention, which, for equalizing the tension caused in the ribbon by the ribbon vibrator movement, provides a yielding driving connection permitting an additional removal of ribbon from the currently winding-up spool counter to its normal turning direction.

Advantageously. the purpose of the invention is obtained by providing as an engaging device for the spool a sleeve freely carried on the drive shaft having a projection continuously urged by a spring against a projection on an engaging member fastened to the drive shaft.

The invention will be more particularly described with reference to the accompanying drawing in which:

Fig. 1 is a semi-diagrammatic representation of a ribbon advancing mechanism embodyini the principles of the invention viewed from above; and

Fig. 2 is a vertical section through the right hand portion of the ribbon drive mechanism of Fig. 1.

The arrangement for advancing the ribbon of a typewriter machine shown in the figures consists, as usual, of driving devices carried by the machine frame for moving the ribbonto the left or right end and a ribbon vibrator i positioned between them which raises the ribbon into printing position. The machine elements connected to the ribbon drive units and with the ribbon support are conventional and are not shown. The

ribbon 2 is represented in its lowermost and up permost end positions by full and dashed lines, respectively. Position I represents the resting position of the ribbon vibrator, while 11 represents the uppermost position of the ribbon vibrator, that is, when the red portion of the rib. bon is in position tor the printing of capital letters, showing the large displacement of the ribbon required. For eliminating the disturbing excessive tension on the ribbon caused thereby, an auxiliary device is provided on each of the drive units for advancing the ribbon, as is to be described.

The drive shaft 3, to for the ribbon spool 4, 40 carries on its upper portion a freely turning sleeve 5, 6a, the outer diameter of which corresponds to the central hole of the ribbon spool. The middle of the drive shaft, a toothed wheel 6, 6a, is fastened by means of a central boss I, la which has an upward extension having a central de pression and a lower extension resting on the U-shaped bearing member 8. Bearing member 8 is provided with vertical perforations to carry the drive shaft 3, 3a, and within the arc of this hearing member a U-shaped lever 9 is freely mounted directly on the drive shaft. A pull wire Hi linked to the shorter underarm of lever 8 provides the necessary connection with the machine for the swinging movement of this lever. Its upper arm carries a spring-loaded dog ll, Ila engaging toothed wheel 6, 6a. A similar dog It, 42a carried by bearing member 8 is provided for stopping the toothed wheel advanced by the firstmentioned dog.

The depression in the upper side of boss I carries two opposed projections lb projecting inwardly from the rim. At the lower end of sleeve 6; lia inside the depression in boss I and moving between projections lb are provided swinging arms I3. I31: which carry at one end a pin Nb and at the other end a perforation for the attachment of a spring i4, Ma. The other end of this spring is attached in a perforation in the outer rim oi boss 1. In order to prevent the unintended sliding of the sleeve 5, in from the drive shaft 3, 3a, a spring ring I5 is provided at the upper end of the shaft.

The method of operation of the follows:

As shown in Fig. 1, the dogs II and I! on the driving unit to the right of the ribbon vibrator are in engaged position for advancing the ribbon, while the dogs i la and Ila on the left-hand unit are disengaged. The left spool thereby can run freely as an unwinding spool. The device for moving the dogs into and out of engagement is not shown in the drawing in order to avoid confusion. In the condition shown in the drawing the ribbon runs in .the direction indicated by the arrow from left to right stepwise simultaneously with'the depression of the keys. Upon depression of a type key the dog i i imparts to toothed wheel 6 a turning motion inthe clockwise direction which strains spring M. The spool body itself, as well as sleeve 5, are at first unaffected by the turning movement, since with the type depression also the ribbon vibrator i is raised and thereby the binding'or pinching of the ribbon in the carrier head exerts a pull on the otherwise winding-up spool. The spring M serves in this period particularly as an energy'storer, that is, it remains tensed so long as the key depression or the carrier movement lasts and is untensioned when device is as the carrier, returning to the resting position, frees the ribbon for unhindered advancement (position I). The toothed wheel 8 is thereby, after advancement by I or 2 to the devices, held in the new position by dog l2, that is, it cannot run in counter-clockwise direction.

The same operations, except in the opposite direction, are provided at the left drive unit in order to obtain a. similar eifect in both directions of movement. It is conunon to both units that the turning motion of sleeve 5, 5a with respect to the toothed wheel 6, to can only extend over a quarter of a circle in order to insure spring I against excessive strain.

The drawing of the ribbon through the ribbon vibrator takes place with this arrangement easily and without binding so that on shifting to the red typing position no disturbances or difhculties are noticed. There is also a further advantage in that the drive which advances the ribbon isv not, as heretofore, positive and eifectlve during the raised position of the ribbon vibrator, but that the energy storing spring l4 only finds an opportunity for untensioning, that is, for carrying out the ribbon advancement when the ribbon vibrator returning to rest position ceases binding the ribbon in the vibrator head. Thereby the disadvantageous eflect of the moredifiicult drive because of excessive tension on the ribbon is avoided and the movement oi the ribbon vibrator is eased.

I claim:

1. Ribbon mechanism for typewriting machines including ribbon spools, supporting and driving means adapted to drive said spools for selectively reversible ribbon travel and a ribbon vibrator intermediate said spool supports in which the path of movement of the ribbon between the spools'in feeding position is substantially rectilinear and movement of the'ribbon vibrator from feeding position to aprinting position displaces the .ribbon by a substantial amount from the path of movement thereof in feeding position, comprising resilient connecting means between said drive means and said spools permitting limited movement of the one of said spools acting as take-up spool in reverse direction to the take-up direction during movement of said ribbon vibrator from feeding position to a printing position.

. 2. Ribbon mechanism as defined in claim 1 wherein said spool supporting and driving means comprises a fixed shaft, a sleeve mounted for rotation on said shaft and engaging the spool for rotation therewith, an intermittently advanced rotary member mounted on said shaft, spring connecting means between said sleeve and said rotary member and interengaging elements carried by said sleeve and rotary member adapted to limit relative rotary movement between the same.

'W ALTER DIECK.

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