US2192627A - Typewriting machine - Google Patents

Description

- March 5,1940. R. VON REPPERT TYPEWRITING MACHINE Filed April 29, 1937 VENTOR ATTORNEY Patented Mar. 5, 1940 UNITED. STATES PATENT OFFICE TYPEWRITING MACHINE Richard von Reppert, Rochester, N. Y., assignor to International Business Machines Corpo ration, New York, N. Y., a corporation of New York Application April 29, 1937, Serial No. 139.636

Claims. (Cl. 197-97) This invention relates to typewriting machines. The broad object of the invention is to provide an improved typewriting machine in which noise is reduced to a minimum.

An object is to provide power operated typewriting mechanism which is quieter and produces more even impressions than prior power operated typewriters.

Another object is to provide means for reducing the noise incidental to the operation of whether within or without the scope of the appended claims and irrespective of other specific statements as to the scope of the invention contained herein.

The single figure is a vertical 'section th'rough a power operated typewriter equipped with the present invention.

It will be convenient to describe the present invention with reference to the well known International" electric writing machine, formerly known as the Electromatic. It will be understood, however, that the invention is not limited in its application to a typewriter of the specific type shown, nor even to power operated typewriters alone, but may be used in manually operated typewriters as well.

The numeral I represents the usual carriage mounted by means of anti-friction bearings 2 on the rails 3 whereby the carriage is niovable for typing ofcharacters on a work sheet carried by the platen l which is rotatably mounted in the carriage I. The spacing of the carriage is effected by suitable escapement mechanism which may take any desired form, hence is here shown very diagrammatically as comprising an escape wheel 5, dog rocker 6 pivoted at I and carrying escapement dogs 8. The escape wheel 5 is mounted on a shaft 9 having a pinion Ill 50 meshing with the usual escapement rack ll secured to the underside of the carriage. By 'oscillating the dog rocker 6 in a counterclockwise direction by means hereinafter to be described, the carriage is caused to move step-by-step in a 55 well known way. The type bars 12 are pivoted pivoted on a fulcrum rod I6 and are guided at their front ends by a comb ll. Springs H3, interposed between the undersides of the key levers, and a fixed part of the framework, tend to restore the keys l5 after each depression and release thereof by the operator. Each key l5 controls a cam unit I9 of well knownform having a doublelobed cam 2|) adapted to cooperate with the power roller 2|. Each cam unit I9 is connected by a link 22 to a saddle 23 pivotally mounted at 24 on a toggle link 25. The right hand ends of the toggle links 25 are pivoted upon a fulcrum rod 26- mounted in the framework and are so shapedas to have stop shoulders 21 engaging a suitable stop such as a bar 28 for limiting the clockwise rotation of the toggle links 25; Sublevers 29, pivotally mounted on the fulcrum rod l6, are connected by links 30 to the type bars l2 which are restored to the position shown in the drawing by means of springs like 3!.1' The toggle links 25 at their left hand ends are connected by links 32 to the sub-levers 29 and are provided with springs 33 which normally tend to hold the stop shoulders 21 in engagement with the bar 28, as shown in the drawing.

As is customary in the typewriter art, the sublevers 29 mustbe of graduated lengths, and bent toward the segment varying extents owing to the fact that the type bars are arranged in a semi-circle in the segment ll whereby their pivot portions are on different levels. Due to the fact that the sub-levers 29 are both graduated in length and bent toward the segment, different extents, individual blanking and forming dies mustbe used in manufacturing each sub-lever. In cider to secure uniform impressions, it is neces ary to exercise close attention to the dimensions of the sub-levers, as well as other parts. and; even with precision manufacture, inaccuracies occur in the parts, particularly the sublev'ers, which, in theassembled machine, very materially affect the uniformity of the impressions made by the types. In order to offset these inaccuracies of manufacture and also to enable the machine to be adjusted for uniformity of impressions in view of difierences in the type face areas of the types, it is proposed to provide means for individually adjusting the type bars whereby each impression is efiected with a force commensurate with the area of the type face.

It is preferred to locate the adjusting means in the train of connections-extending from the type bar to the means'for supplying the propulsive force for operating the type bars. This last a means may be either a manually operated key the stimulus of the operating for'ce'which in the present case is applied by the power mechanism comprising the power roller 2| and cam units 20. The saddles 23 are U-shaped in vertical section so as to partly surround the toggle links with the pivot 24 passing through both arms of the saddle. Adjusting screws 34 are screwed into threaded holes in thesaddles opposite the top edges of links 21 on opposite sides-of the pivots 24. Screws 34 engage the top edges of the toggle links 25 and lock the saddles securely in their adjusted positions. These saddles, in effect, are arms which are pivotally adjustable in relation to links 25 by means of screws 34 to vary the radial distance from the center of fulcrum rod 26 to the point where the links 22 are pivoted to the saddles. The saddles 23 are adjustably rotated in a clockwise direction to reduce the amount of oscillation of the sub-levers 29 and counterclockwise to increase the oscillation of the sub-levers.

It is necessary in power operated typewriting machines to positively propel the type bar only a part of its stroke and then permit the type bar to finish its stroke by virtue of the momentum stored therein. The point at which the positive operating force applied by the power mechanism and momentum takes. effect is variable in the various machines being dependent on the mass of the movingparts and other factors. The reason for this is that in power operated machines, the type bars are operated with such speed that the type would cut through the ribbon and paper unless the momentum movement is provided which permits the type bars to decelerate some- I what or at least not to continue to accelerate as heavily that differences between them are not noticeable, but as the number of carbon copies increases, the impressions of the type faces having a large area become fainter whereby the last carbon copy is noticeably poorer than the first in respect to uniformity of impressions. In order to avoid this effect, it is necessary to resort to some such expedient as increasing the speed of the driving motor, but. thisis objectionable because the excessive force applied to the type bars having types of small area of face causes embossing and cutting of the copies and also excessive impactnoise.

In spite of careful m anufacturing, it is impossible to obtain and maintainprecise accuracy of the parts and these unavoidable inaccuracies or variations cause variations or non-uniformity of the typing impressions. A slight variation of the frictional conditions while the type bar moves by momentum, will afiect its impact velocity and this will show up as an accentuated variation in the typing impression, as the work done by the type bar or its kinetic energy increases as the square of its velocity.

By adjustably rotating the saddles 23, the point at which the positive operating force applied by the cam units acts on the toggle link 25 may be varied without, however, affecting the initial position of the type bars. Thus the extent to which each type bar is rotated positively and hence the point atwhich momentum takes effect to complete the stroke of the type bar may be adiusted to correspond with the area of the type face and to compensate for any frictionalcondition and dimensional differences in the sub levers and other slightly off dead center in a vertical direction.

when the stop shoulders 21 are engaging the bar 28 whereby it is impossible to rotate the type bar 3 in a counterclockwise direction except by applying a counterclockwise rotational force to the links 25. The toggles comprising links 25 and 32 thus provide means for preventing rebound of the type bars when they return to normal position.

When a key, I5 is depressed, its cam unit I9 is rendered operable by the power roller 2| in a well known way whereby the cam unit is rocked clockwise or counterclockwise, depending upon whether it is located at the back or the front of the power roller 2|, the front side of the power roller being, of course, the side on which the keys l5 are located. Theoperation of a cam unit by the power roller causes the appropriate one of the links 22 to be drawn downwardly, thereby rocking one of the toggle links 25 in a counterclockwise direction, which, of course, bends the toggle including that link and causes the associated sublever 29 to be rocked in a clockwise direction, thereby drawing link 30 to the right and causing the proper type bar l2 to be rocked in a counterclockwise direction to type on a work sheet on the platen 4. Springs 3| and 33 cooperate to restore the operated type bar l2. and the associated toggle link 25 to the position shown in the drawing.

Heretofore in typewriting machines, it has been customary to provide a semi-circular universal bar which was mounted on or adjacent the segment in such fashion that during the course of the movement of the type bar to printing position it would engage the universal bar and cause the universal bar to' be moved in the same direction as the type bar to thereby operate the escapement. The universal bar has in the past been mounted in various ways, of which the one used in the International electric writing machine may be used for purposes of illustration herein. In this machine, the universal bar takes the form of an open frame 35 mounted upon flat leaf springs 36 and having a semi-circular portion 31 thereof projecting into 'a semi-circular slot formed in the segment |4 so as to be engageable with the type bar at a point near the pivot wire |3. There are two leaf springs 36 which are mounted as shown in Patent No. 1,936,466 to support the universal bar at four points for movement of every part thereof an equal. amount under the impulsive force of the type bar.

In the present case, the universal bar is shown as connected by a link 31a to a bell crank 38 pivoted at 39 on a bracket 48 carried by the framework. The other arm of the bell crank 38 is connected by a link 4| to the dog rocker 6. In order to permit operation of the dog rocker 6 under control of a cam unit (not shown) which in turn is controlled by the spacebar of the machine,'link 31ahas a pin and slot connection to the universal bar whereby the parts 31a, 38, 4|, and 6 may be mocked independently of the universal bar.

It has been found that while the bulk of the machine is caused by the impact of the type on the platen, a very large part of the noise is attributable to the operation of the escapement mechanism and particularly to the impact of the type bar upon the universal bar which results in a sharp click every time a type bar is operated. This is due to the fact that the type bar in most commercial-machines rotates through quite an appreciable arc and acquires considerable momentum before it engages the universal bar. This means that the universal 'bar must be started from a stationary position and brought up to its maximum speed substantially instantaneously. One of the objects of the present invention is to modify the mechanism of the typewriter to such an extent that the universalbar is started into motion and restored to normal position gradually, whereby to avoid the impact noise of the type bar with the universal bar in machines heretofore known in the art. For this purpose there is associated with each type bar l2 a pendant 42 which has a contour 42a approximating a rolling contact curve which is adapted to roll over the surface 1212 on the edge ofthe type bar. pendants 42 are pivoted upon a fulcrum wire 43 mounted in the segment I 4 and rest upon the front edge of the semi-circular portion 31 of the universal bar. The pendants 42 are pressed against the edges of the type bars in the rear of the fulcrum wire l3 by means of the leaf springs 36 which support the universal bar.

When a type bar is operated, it will be noted from the drawing, that it will rotate a predetermined amount before it commences to actuate the pendant and will then actuate the pendant through the rolling contact engagement of the curved surface 42a with the surface l2a of the type bar, the pendant 42 associated with the operated type bar being rotated in a clockwise direction with increasing velocity, thereby causing the universal bar 31 to move rearwardly with increasing velocity which quickly decreases to zero as was formerly the case, but starts the universal bar from rest with gradually accelerated motion and, in restoring, the type bar permits the universal bar to be restored-by springs 36 with gradually decelerating motion. It is evident,therefore, that the-universal bar is started into motion and restored without any of the shock which characterized the prior universal bar mechanisms used in typewriters. By preventing this impact a between the type bar and universal'bar from taking place, a very large part of the noise incidental to aprinting operation is eliminated.

While there has been shown and described and pointedout the fundamental novel features of the invention as applied'to a single embodiment it "will be understood that various omissions and substitutions and. changes in the form and details of the device illustrated and in its operation may be made by thoseskilled in the art without departing from .the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is: I

bars

The,

1. In a typewriting machine, a segment, type bars pivotally mounted in the segment, a universal bar mounted adjacent the segment, a series of elements pivotally mounted in the segment, each element being in the plane of one of the type bars and also in engagement with the universal bar, said elements having curved edges contact- 4 ing with the edges of the type bars whereby a rolling contact driving relation exists-between ing to a maximum and then decreasing to a minimum throughout the stroke of the type bar. 2. In a typewriting machine, a series of type bars, means for actuating the type bars, a universal bar common to the type bars, and a series of pendants adapted to operate the universal bar, each associated with a type bar and having rolling contact therewith, the contact surfaces of the pendants and ,type bars being adapted to cause the universal bar to be started from rest with gradually increasing velocity during the stroke of the type bar.

3. In a typewriting machine, a platen, a segment, type bars mounted on the segment and movable toward the platen to write on a work sheet in front of the platen, carriage feeding mechanism, a universal bar connected to the car riage feeding mechanism, means to operate the type bars, and a series of elements pivotally mounted on the.;s'eg'ment, said elements engaging the universal bar and having a rolling. contact engagement with-"the type bars for imparting movement to the -universal bar, each of said elements being .adaptedto accelerate the universal bar from rest with'gradually increasing velocity.

4. In a machine of the class described a segment, a seriesof type bars pivotally mounted on the segment, said type bars having their pivots disposed in an arc on the segment, a-universal bar; a. series of interponents pivotally mounted on the segment and disposed in an arc concentrio with the are ofthe pivots for the type bars, said interponents being each associated with a type bar and each having a curved edge in rolling contact engagement with its type bar; and an arcuate universal bar engaged by the interponents and operated thereby, the curved edges of said interponents being adapted to start the universal bar from rest with increasing velocity as the type bar approaches the printing point and to decelerate the universal bar to zero to the printing point.

5.,In a machine of the class described, typing means comprising a series of'types-movable .to and from a printing: position and means to actuate the types including trains ofoperating connections to the types, a universal bar; and a series of interponents, each associated with a type and interposed between the universal bar and a part. of the train of operating connections to the corresponding type, said interponents being rotatably mounted on pivots which remain fixed while the types are moving to the printing point, each of said interponents being provided with a curved portion having rolling contact with the aforesaid part of the operating train to the associated type, said curved portions being so designed that the increasing velocity during the stroke of each type.

. RICHARD von REPPERT.

universal bar is started from rest gently with

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