US2078268A - Typewriter action - Google Patents

Description

April 27, 1937. A. F. MULHARE TYlEWRITER ACTION 2 Sheets-Sheet l INVENT/O.

Original Filed Aug. 11, 1922 A ril 27, 1937. A. F. MULHARE 2,078,268

TYPEWRITER ACTION Original Filed Aug. 11. 1922 '2 sheets-sheet" 2 BY MM oRN x Patented Apr. 27, 1937 UNITED STATES PATENT OFFICE 581,149, August 11,

1922. This application July 7, 1934, Serial No. 734,098

Claims.

The present invention relates to an improvement in the action or mechanism of a typing machine by which the printing is effected, and has for its principal object the provision of a novel, simple and reliable construction of key levers, type bar, type bar connections and mounting for the same in a combination and arrangement whereby a substantially uniform movement of the finger keys will produce an accelerated movement of the type bars, thus obtaining a crisp and eifective stroke with a prompt return of each type bar.

My improved mounting for the connections between key levers and type bars insures uniform action of the various type bars, and lends itself to prompt and easy assembling of parts. A further important advantage is found in the fact that my construction makes it possible to obtain direct and uniform connection between the parallel finger key levers and the series of cylindrically nested type bars at the end and intermediate positions as well as in the middle; and this is accomplished in my preferred construction by means of key levers interchangeably constructed throughout any one bank or row. Further advantages of the invention will become evident hereinafter.

The invention is illustrated in a preferred form in the accompanying drawings, wherein Figure 1 90 is a longitudinal sectional view of a part of a typing machine, showing one set of key levers and type bars in elevation together with a suflicient portion of the remainder of the machine to make the operation of my invention clear; Figure 2 is 05 a sectional view of certain details of mounting; Figures 3 and Ba; are respectively a partial plan view and an end elevation of the guide block for mounting the connecting bars; Figure 4 is a front elevation of the entire machine, certain parts being shown in section on the line 44 in Figure l; and Figures 5 and 5a are identical parts of any two key levers in the same bank or row.

The framework of the machine, shown at H], supports the platen on the usual carriage l2, as well as a set of type bars l3, nested in a well known manner in front of the platen. Each of the type bars has a rearward extension or arm |4 formed with a slot I 5, as clearly shown in Figure 1.

The finger key levers |6 are made of thin metal, and are normally supported as shown in Figure l.

A straight fulcrum bar I! is mounted in a bracket H1 at the rear of the frame, and extends from one side to the other of the same. Each finger key lever 16 is notched at its rear end, on its 55 upper edge, and each notch is fitted over the fulcrum bar l1, being held up against the same, as by the spring l9, which spring also keeps the forward upper edge of the bar normally in contact with the stop cushion 20.

Power is transmitted from each finger key lever l6 to its corresponding type bar l3 by a swinging connecting bar or lever 2|, preferably stamped out of sheet metal. Each lever 2| carries a pin or roller 22 at its upper end which engages the slot I5 in the extension M of the type bar, and a second pin or roller 23 at its opposite end engages a cam slot 24 cut or stamped in the key lever.

The upper edge of the slot 24 is shaped upon a curve, so calculated and arranged that, when the lever I6 is depressed, this edge acts as a cam upon the pin 23, forcing it to move toward the right in Figure 1, while sliding along said curved edge. This swings the upper end of the lever 2| to the left in Figure l, and the pin 22 is thus caused to slide along the front edge of the slot 5, while forcing the same forward, and causing the type bar |3 to swing rapidly upward and against the platen As the upper arm of the lever 2| is longer than the lower arm, and, as the forward extension of the type bar I3 is longer than the extension M, the full ninety degree swing of the type bar will be accomplished by quite a small angular movement of the lower arm of the lever 2|. Owing to the shape of the operating cam edge of the slot 24, this small angular movement of lever 2| will be accomplished by a still smaller swing of the key-lever 6.

It will be seen that, by using a roller or pin (22, 23) at each end of each lever 2| and by fitting it closely to the two sides or edges of the slots (I5, 24) through which the pins project, the movements of the type-bars I3 are confined, and all looseness is avoided and the position of each type bar is always controlled positively by the finger key lever, thereby producing a perfect impression on each stroke without danger of rebound with a consequent shadow impression. This arrangement also causes the key lever springs I9 to aid in producing the return of the type bars immediately after each impression is made. Furthermore, since each pin (22, 23) is constantly in contact with the operating edge of the corresponding slot, there is always a smooth action with a minimum of noise and wear.

To obtain the maximum effectiveness in an arrangement of the kind described, wherein the type bars l3 swing through ninety degrees, the shorter arm M of each type bar should swing through forty-five degrees on each side of the plane in which the type bar bearings lie; and in the embodiment illustrated, each of these fortyfive degree angles of the type bars i3 is produced by a swing of less than fifteen degrees of the longer arms of the levers 2|, 1. e., less than thirty degrees for the full swing of ninety degrees of the type-bars It. At the same time the two arms of the levers 2i make such an angle with each other that the shorter armsdescribe the total angleof somewhat under thirty degrees or less upon occurrence of a depression of the key-levers which is uniform for all the key levers, which depression is determined by the form of the operating cam slot 24.

If the velocity of each lever 2! were uniform throughout each swing, in the arrangement shown, the fact that the pin 22 first approaches and then departs from the type bar bearing, would produce at first an accelerating and then a decelerating swing of the type bar, which would be the opposite of desirable. I, therefore, prefer to so shape the operating curve of the slot 24 in each finger key lever 16 that the forward swing of the connecting lever 21 will be accelerated to such a degree as to overcome the effect above noted, and will produce, on the contrary, a material acceleration of the type bar i3, especially toward the end of its movement. This gives a snappy stroke and return action, which conduce to excellence of impression. By arranging the pin 23 to swing through a relatively small angle in the lower part of its circular arc of movement, as shown, the variation in the effective leverage of the lower (shorter) arm of lever 2! is minimized, and the exact degree of acceleration desired is easily produced by suitably calculating the curve of the cam slot 24.

Another of the important features of my present invention is found in the special mode of mounting the swinging connecting levers 21, so

that they can be readily assembled, and, at the same time, be perfectly aligned and guided, while accommodating their action to the usual semicircular nesting of the type bars shown in Figure 4.

For this purpose, a supporting guide block 25 is provided, which extends from side to side across and over the key levers l6. As shown in Figure 4, this block 25 is provided with a slot for the fulcrum-rod 29 which is curved downward (preferably on the arc of a circle having a radius of about eighteen inches) and the block is conveniently supported by lugs 26, removably secured to a part of the frame ill, as by screws 2?. Referring to Fig. 1 in which a type-bar it at the middle of the nest and its related key-lever l6 and connecting-lever 2| are shown, the two arms of lever 2i, upon depres sion of the key-lever it, are moved through angles of somewhat less than thirty degrees in. producing a movement of ninety degrees of typebar l3,'from the position shown, to a printing position in front of the platen H. The levers 2! from the middle of the nest toward each end produce movements of ninety degrees of the type bars I3, for equal depressions of the key levers l6 by movements through progressively less than thirty degrees, as hereinafter explained.

The rearward portion of the block 25 is cut to form as many parallel vertical guide slots 28 as there are connecting levers 2i, and each lever 2| is slippedinto one of these slots, where it is supported by a bearing rod or wire 29 which is passed through. holes or openings 30 pierced in the connecting levers 2!. These last named openings 30 are countersunk from each side, as shown in Fig. 2, in order that the connecting levers 28 may turn freely on the fulcrum rod 29, and may swing freely each in its own vertical plane, determined by the contact between the fiat sides of the levers 2! and the sides of the slots 28 in which these levers turn. The opening in the block 25 for the fulcrum-rod 29 is preferably in the form of a groove or slot 25 (Fig. 3a) running into said block from its upper face. When the parts are assembled, the fulcrum-rod 29 rests against the bottom of said slot.

The wire 29 (shown in dotted lines in Fig. 4) is curved on the arc of a circle corresponding to the curve of the slot 25 in block 25, so that this .Wire or rod may readily be threaded through the holes in the levers 2i and slid along the bottom of the slot 25' in the block 25.

As shown in Fig. 4, owing to the semi-circular nesting of the type bars R3, the upper arms of the connecting levers 2i furthest from the middle of the machine are bent inward considerably, and are necessarily much longer than those at the middle. This bending and this excess of length diminish gradually as the middle is approached. In order that a given or certain amount of depression of a key of one key-lever I6 may produce the same speed and acceleration of its type bar as is produced by the same amount of depression of every other key, the successively longer connecting levers 2| must be so mounted as to preserve a constant ratio between their two arms on opposite sides of their respective fulcrums on rod 29. It is a part of the arrangement for accomplishing this purpose that the bearing rod or wire 29 is curved as shown and described. Moreover, by reason of the progressively increas-.

ing lengths of the arms of connecting levers 2i,

from the middle position toward the end positions of the nested levers, the angles which these arms make with vertical planes at and lengthwise of rod 29 at the respective points of bearing on rod 29 of the connecting levers, are progressively less from the middle position to the end positions, so that the distance traversed or amount of movement described by the pins or rollers 22 will be equal to the lengths of the arcs of movement.

In practice it is found that this inclination of the plane in which the curve of rod 29 lies shouldv be substantially identical with the normal backward inclination of the connecting lever 2! in the middle of the group of these levers (as shown in Figure 1) and this angle is a little less than fifteen degrees from the vertical as heretofore described.

It is a peculiarity of my mounting that all the pins or rollers 22 at the upper ends of the levers 2! lie in a common vertical plane. This is indicated in dotted lines in Figure 1, wherein a circle indicating the pin 22 of a lever near one end of the row is shown connected by a vertical dotted line with the pin 22 on the middle lever 2 I. It is also a peculiarity of my arrangement that the pins or rollers 23 on the lower ends of lovers 2 I are all in alinement, notwithstanding the progressively greater length of the lower arms of the levers 2! from the middle to the ends of the group.

The importance of this arrangement is found in the fact that it makes it possible to make all the cam slots 25 identical in all the finger key levers It oi the same lengththat is to say--in the same bank or row. By thus making all the key levers of each row interchangeable it is not necessary to identify the position of each in its row-as hitherto essential-it being only necessary to put a given lever into the right row, which is instantly determined by the length of the lever. This greatly facilitates assembling. This feature is exemplified in Figures 5 and 5a. which show the slotted portions of any two key levers ill of the same row, showing the identical shape and position, with respect to the lever, of the cam-slots 24.

Various changes may be made in this construction without departing from the scope of my invention, which is not limited to the details herein shown and described.

This application is a substitute for my previous application, Ser. No. 581,149, filed August 11, 1922.

What is claimed is:

1. In a typewriter action, a pivoted type bar, a swinging connecting lever mounted between its ends, said lever having a pin and slot connection with the type bar and having a pin at its lower end, and a key lever fulcrumed behind said connecting lever and having a cam lying normally against said pin and adapted to swing the lower end of said connecting lever backward to approximately the vertical line through its pivot when the key lever is depressed whereby the variation in the eiiective leverage of the shorter arm of the connecting lever is minimized.

2. A typewriter action of the character set forth in claim 1 hereof wherein the rear end of the type bar and the upper arm of the connecting lever swing together across a line joining their respective bearings, and wherein the operative cam surface of the corresponding key lever is shaped to produce a sufficiently accelerated swing in the connecting lever to overcome the unfavorable changes in leverage due to the pin and slot connection at the type bar and impart an accelerated movement to said bar during the latter part of its movement.

3. In a typewriter action of the character set forth in claim 1 hereof, a guide block for the connecting levers having parallel guide slots and a common bearing rod for the connecting levers, said rod being bent in the arc of a circle and being laid in openings in the guide block and passing through the connecting levers; the openings in the connecting levers being countersunk to permit them to swing in parallel planes in said guide slots on the curved rod as a bearing.

l. In a typewriter action of the character set forth in claim 1 hereof, a series of bearings for the connecting levers arranged in an upwardly concave curve lying in a plane inclined backward from. the vertical.

5. In a typewriter action, a plurality of nested type bars converging to a common printing point, a plurality of pivoted connecting levers respectively connected therewith by direct pin and slot connections, and a key lever for each connecting lever, each connected by a direct pin and cam connection, all the functioning parts of the key levers in a row being identical in form and position so that all key-levers in a row may be assembled with their connecting levers without differentiation.

6. In a typewriter action, type bars, key levers, and intermediate connecting levers each connected directly to a type bar and to a key lever, in combination with a common mounting for the connecting levers comprising bearings for said levers which lie in a curve whose plane is inclined backward at substantially the same inclination as that of the position of rest of the connecting levers at the middle of the series.

7. In a typewriter action, nested type bars and connecting levers directly connected therewith by pin and slot connections and having pins at their lower ends, said type bars and connecting levers being mounted so as to swing together across a line joining their respective bearings; in combination with key levers fulcrumed behind said con necting levers and having cams engaging the pins at the lower ends of the connecting levers whose operative surfaces are shaped to produce a sufficiently accelerated swing in the connecting levers to overcome the unfavorable changes in leverage due to the pin and slot connection at the type bar and impart an accelerated movement to said bars during the latter part of their movement.

8. In a typewriter action, type bars, connecting levers operatively connected therewith, a guide block for the connecting levers having parallel guide slots and a common curved bearing rod for the connecting levers, said rod passing through openings in the guide block and connect ing levers; the openings in the connecting levers being countersunk to permit them to swing in parallel planes on the curved bearing rod as a bearing.

9. The combination, in a typewriter action, of a plurality of type-bars provided with operating arms, pivots for said type-bars arranged in a curve, said typebars lying substantially horizontal in their retracted positions, a plurality of keylevers having pivots below and at the rear of the type-bar pivots and arranged with their key-ends in a plurality of rows, connecting-levers joining each key-lever with a type-bar-arm, a pin-andslot connection between each end of a connectinglever, and a key-lever and a type-bar-arm, pivots for said connecting-levers intermediate the ends of said connecting-levers arranged in a curve which lies in an inclined plane, said connectinglevers having arms of progressively increased length from the middle to the ends of the set, the arms of said connecting-levers from the middle to the ends of the set being of progressively decreased angularity with respect to vertical planes passing through and lengthwise of the pivotal bearings of the respective connecting levers, and the key-ends of the key-levers having substantially the same amount of depression-movement.

10. A combination according to claim 9, wherein the ends of the connecting-levers move through arcs of substantially equal length.

11. A combination according to claim 9, wherein the type-bar-arms move across a line joining the pivots of the type-bar-arms and of the connecting-levers, and said slots of the connection between the key-levers and connecting-levers are shaped to accelerate the movements of the typebars in the latter part of their movements caused by the depression of the key-levers.

12. A combination according to claim 9, wherein the pin-and-slot connections between the keylevers (of any set in which the key-ends are arranged in a row) and the corresponding connecting-levers comprise identical slots in said row of key-levers.

13. A combination according to claim 9, wherein the slots of the connection between the keylevers and connecting-levers are shaped to accelerate the movements of the type-bars in the latter part of their movements caused by the depression of the key-levers, all of said key-levers of any set in which the key-ends are arranged in a row 10 being identical.

14. A combination according to claim 9, wherein the pins at the upper ends of said connectinglevers all lie in a common vertical plane and the pins at the lower ends of said connecting-levers all lie in alinement.

15. A combination according to claim 9, wherein the ratio between the lengths of the arms of the connecting-levers on each side of their pivots is constant.

ANDREW F. MULHARE.

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