US2142375A - Typewriting machine - Google Patents

Description

Jan. 3, 1939. T R. v 'REPPERT TYPEWRITING MACHINE Fild sept. 22, 1954 Ra/M Eg TOR.

' A TT NE YS.

' the printed characters.

Patented Jan. 3, 1939 UNITED STATES PATENT OFFICE to International Business Machines Corporation, York, N. Y., a corporation of New York Application September 22, 1934, Serial No. 745,050

13 Claims.

This invention relates to typewriting machines in general.

'Ihe broad object of the invention is to generally improve type bar actions used in typewriting machines of the so-called silent or noiseless type.

'I'he invention will be described herein in connection with a typewriting machine but it is not limited in use to such a machine as it may be used in any machine in which quietness of operation is desired and wherein printing is accomplished by means of type bars.

YHeretofore the type bars or type slugs of socalled noiseless typewriters have been actuated by very complicated linkages in which toggles and weights are an important part, the object, in the main, being to cause the types to be impressed against the work sheet on the platen by pressure rather than by a percussive or hammer-like blow. These complicated linkages have many pivots, springs and small and delicate parts which are subject to rapid wear due to the not inconsiderable mass of the parts and the difculty of keeping the connections adequately lubricated. It is necessary to keep these complicated linkages carefully adjusted as wear has a cumulative effect by which a small amount of wear in a few pivots has a very pronounced eiect on the quality of the impressions made by the types, affecting both the alignment and clearness of As a rule, these linkages are not very readily accessible for adjustment, cleaning or lubrication so that there is room for considerable improvement in these respects alone. Due to the. large number of parts required per type bar or slug, when compared with the type bar actions of theA conventional type of machine long in use prior to the development of noiseless machines and now the most extensively used, the noseless machines developed and on the market up to the present time are very expensive to manufacture.

The well known conventional type bar action, .in which a simple type bar pivoted in a curved wire segment is rocked through an angle of approximately 90 to strike normal to the surface of the platen, has been found by long experience to be the cheapest and most satisfactory of any, and is now the construction adapted by the great majority of the manufacturers of typewriters. automatic-letter writers, and printing telegraph receivers. This form of construction is the simplest and cheapest to manufacture but has one serious defect in being very noisy as the types strike the work sheet by a percussive or hammer-like (Cl. IWI-27) blow which is very loud, particularly in machines operated by power like the well known Electromatic, Woodstock, and others. Attempts to eliminate or even reduce the noise of impact of the type bars by the use of special noise absorbent platens have been unsuccessful, hence the only real solution of the noise problem seems to lie in controlling in some fashion the type bars whereby their movement is arrested or retarded just before they strike the work sheet and they are caused to strike the work sheet practically noiselessly yet with sufficient pressure to produce clear impressions. Prior attempts to accomplish this result have led to very complicated linkages having many small parts to lubricate and adjust. As it is difcult to adequately protect vthese linkages against dust they soon become very dirty and the oil often becomes so gummy that the parts stick and bind, the type bar action becomes sluggish, and the keys feel stiff in action. As a result the general quality of the impressions produced by the types suffers considerably. y

All of the commercial noiseless typewriters employ, in some form, the complicated toggle and weight linkages mentioned above to secure noiseless operation, Patent No. `1,817,253 disclosing the type-bar action of a Remington-Noiseless No. 6 machine being merely an example of a typical construction. 'Ihis machine has given 30 excellent results but is too complicated and costly to manufacture. As a general rule the noiseless machines are more costly than the conventional machines.

The present invention has for its main purpose to reduce the number of working parts and pivotal connections necessary to produce silent operation of type bars and eliminate thecomplicated toggle mechanisms heretofore thought necessary and replace them with simple impression controlling elements not positively connected with the type bar as by meansv of links but adapted to regulate the pressure of the type bar at the printing point preferably by rolling contact between the type bar and impression controlling element while the type bar is being moved to the printing point.

Various more specic objects. advantages, and features of the invention will be mentioned at appropriate points in the following description.

The two figures of the drawing illustrate diagrammatically how the invention may be incorporated in a machine of the so-called portable type, Fig. l showing the type bars and associated parts in normal position while Fig. 2 shows them in printing position.

'l'he keys Il may take any well known form and may be pivoted. on a cross rod or wire I I supported in any desired manner, or individual pivots may be provided. Springs I2, each anchored to one of the keys I 0 and to a bar I3 extending crosswise of the machine, hold the keys Ill up against a stop bar Il which is usually faced with a. strip of felt or other sound deadening material I5.

'Ihe type bars I6 may be pivoted in the conventional Way in slots I'I in a segment I9 by means of a wire I9 secured in a slot cut in the segment I8, The slots I1 are arranged in an arc in the conventional way and the free ends of the type bars, adjacent the types 20, normally rest on a rebound pad 2I suitably supported. The type bars I6 are bent laterally diilerent extents adjacent types 20 to enable them to strike the platen 22 normal to the surface and in the same vertical plane and are spaced sufilciently to enable the types to rest on the rebound pad 2l without interference. Secured to the segment I9, and extending upwardly to a point just below the printing point, is a type bar guide 23 of conventional form. This guide merely steadies the type bars I6 against transverse vibration due to lateral spring action of the type bar and the slight looseness of the type bar in its slot Il. It also compels type bars which by accident may have become veryslightly sprung to one side or the other to strike always at theV same point and in the same vertical plane.

Each type bar has a short operating arm 24 connected by a link 25 to one arm of a bell crank 26 pivoted at 21 on a cross rod or upon an individual pivot as desired. Each bell crank 26 is connected to one of the keys I 9 by means of a link 29.

'I'he general construction so far `described is typical of the majority of the type bar actions employed in typewriters and many other ma chines such as automatic letter writers, printing telegraph receivers, and combined typewriters and statistical record card punches. It is cheapest to manufacture and assemble and givesexcellent service as it is easy to clean and oil, and is readily disassembled for repair. This is the conventional construction mentioned above.

It will be noted that depression of any key III causes the associated type bar I6 to move very rapidly so that the type 20 strikes the platen with considerable force producing a loud noise. This noise is very disagreeable in manually operated machines and considerably more so -n power operated machines.

Attempts to silence this noise in machines having the foregoing conventional type of construc-` tion have not been completely successful and have resulted in very complicated mechanisms which are difllcult to clean, oil, and adjust and expensive to manufacture. In present types of commercial noiseless machines, the printing is eifected by intricately shaped type bars or slugs unlike the type bars I6 and mounted in various san-raars at an acute angle which is not a circumstance favorable for producing a clear impression, par. ticularly when carbon copies are desired.

Type bars like those designated I6 in Fig. 1, on the other hand strike normal to the surface of the platen and produce clear, even impressions, provided, of course, the ribbon is not too dry.

The present invention retains all the desirable features of the conventional type bar construction while obtaining quietness and cheapness of manufacture. These added features are obtained merely by providing each type bar with an impression controlling element 29, which is designed to have a rolling contact with a part of the type bar. 'Ihe elements 29 are pivoted on a rod or wire 30 secured in a groove cut in a. frame 3| which frame fis arcuate in shape so that wires I9 and 30 are substantially concentric with respect to a common axis. Each element 29 is adapted to store kinetic energy and for this purpose is made of metal considerably thicker than the sheet or strip from which type bars I6 are blanked., The elements 29.are spaced from. each other by being mounted in slots 32 cut in frame 3|, so that the manner of mounting elements 29 is the same in principle as the manner of mounting type bars I6 in segment I9. 'I'his construction greatly facilitates.V assembly and removal for repair or replacement of broken parts. Anchored to an ear formed in each element 29 is a restoring spring 33 the other end` of which'is anchored to an arcuate bar 34.

Elements 29 have a bulbous outline which may be aptly likened to that of a very common form of gourd. One edge is adapted to have rolling contact with a curved extension 35 formed in the associated type bar I6 and for that purpose a portion of element 29 conforms at 29a to a lsuitable curve such as a logarithmic spiraland at 29b to the curve of an involute.

The extension 35 likewise has curved portions 35a, 35h conforming in reverse to the portions 29a, 29h. The curved portions 29a, and 96a, are so disposed that contact between element 29 and extension 35 is as nearly true rolling contact as quantity production of the parts will permit. The curves of contact are so selected that the initial angular velocity of the type bar produced by depression of a key I0 is very rapid but is gradually reduced as the driving ratio between the extension 36 and element29 becomes greater, until, when the type bar is about to strike the platen (Fig. 2) ,.the angular velocity of thetype bar is very low. The reverse is true of control element 29 due to the initial low driving ratio and the ultimate high driving ratio between extension 35 and element 29 attained when the type 20 reaches the printing point. In other words, the angular velocity of the type bar ranges from zero in the initial position of Fig. 1 through a maximum to approximately zero in the position of Fig. 2, while the angular velocity of element 29 ranges from zero in the position of Fig.

1 to a maximum in the position of Fig. 2. As a result the element 29 stores a large amount of kinetic energy during its movement which reaches a maximum value when the type 2I| is about to make an impression and this energy is available for producing the impression.

The element 29 is provided with an rextension or heel 29e which is connected to the pivoted portionl of element 29 by a bowed portion 29d preferably having a certain amount of resiliency. The extension 29c is spaced a short distance from the curved portion 29h to provide a bulbous gap or opening for the tip 35e oi.' the extension 35 to enter.

Extension 29e is adapted to contact with the part of the extension 35 behind curved portion 35h when the type bar is very close to the printing position. Curves 29h, 35h are so chosen that,

as the type bar is about to reach printing position movement of the type bar at the point of contact with element 29 is at right angles to the movement of said element so that pressure exerted by the curved surface 35h on the surface 29h is directed toward or slightly to one side of the center of pivot wire and has no tendency to turn element 29. As a result the type bar beyond this point, is locked against further movement in response' to pressure exertedv on the key. Thus element 29 has the effect of reducing the velocity of the type bar almost to zero which would actually be the case if the element 29 moved no further.

At the point where the locking action takes effect, the extension or heel 29o comes into position behind curved portion h so that the tip ofthe extension 35 slips partly into the bulbous gap formed by the bowed portion 29d. The kinetic energy which has been stored in element 29 now causes the latter to exert pressure on the extension 35 through heel 29o and the relation of surfaces 29h, 35h is such that continued movement of element 29 permits the type bar to move slowly a very small amount toward the platen in response to the pressure exerted by the heel 29c in element 29. This pressure is quite considerable and is effective to cause the type 20 to make a clear sharp impression on the Work sheet.

The elements 29 may be hardened and given a spring temper in the bowed portion 29d in order to avoid the necessity for very accurate machining of the portions 29h, 29d of element 29 to said tip as by welding, brazing, or riveting.'`

, The key action is very light due to the fact that links 25 and the arms of bell cranks 26 to which the links are attached are in substantially a straight line and therolling contact relation between element 29 and extension 35. As has already been pointed out,the initial driving ratio between extension 35 and element 29 is quite low whereby little force is required to initiate movement of the type bar. This feature enables a high angular velocity to be initially imparted to the type bar which is quickly reduced when the type bar is close to the printing position. This permits operation of the machine at high speed. Since there are few pivots and links used there is less sluggishness in action due to inertia and pivot friction and this feature of the construction also enables operation of the 'machine at high speed. Y

It will be noted, that considering only the type bar 35 and its controlling element 29, and disregarding the specic means used to actuate the type-bar ( links 25, 28, bell crank 26, and key I0), only two pivots are required, both of which are fairly accessible to the operator making the machine easy to clean and lubricate. Furthermore, vertical alignment of the printed characters depends only on the wear at the pivot wire I 9 which has been found by experience to be negligible even in standard machines for oilice use where service is severe.

An important feature of the invention is the elimination of yfrictional losses and structural complexities, and long service obtainable by the use of a type bar mounted in the conventional way and striking normal to the platen;

Another featureis the quietness of operation which is a consequence of theoperation and control of the movement of the type bar by rolling contact with the control element.

It is usual in noiseless typewriters to adjust the machine so that the type bars are positively arrested in front of the platen without actually striking it, the adjustment being such, however, that the faces of the types strike the surface of the work sheet, regardless of its thickness. For this purpose, there is usually provided an impression controlling device for regulating the distance from the platen of the point at which the type bar is positively arrested. In the present invention the curve 29h is so designed that the tip 35e of extension 35 is positively stopped by element 29 before the type can strike the platen but far enough from the platen to enable a clear impression to be had. In order to regulate this distance to allow for different thicknesses of paper, cards, and envelopes, andto make carbon copies, any suitable means may be provided to cause the platen 22 and segment I8 to move relative to each other.

The specific means for applying the initial operating force to the type bars is not a vital feature of the mechanism described. When used in portable machines where compactness, simplicity, and low cost are important, the key connections shown in the drawing may be used. In the case-of manually operated machines designed for olce use, the type bars may be operated initially by means of any of the common forms of sub-levers, such as the well known pin and cam slot construction.

Power units like the ones used in Electromatic, Woodstock, and other power operated machines may be employed as an alternative form of operation.

Many modifications may be made in the construction described herein Without in any way departing from the broad principles of the invention; therefore, it is not desired to be limited to either the specic form of construction or the specific means for operating the mechanism disclosed, but to be limited only by the extent of the prior art.

I claim:

1. In combination with means to actuate a printing element to a printing position, and a member driven by the actuating means, a control element having smooth rollingcontact with said member to regulate its velocity and hence the velocity of the printing element, said control element absorbing kinetic energy from the actuating means while the printing element is being actuated to printing position, and being provided with means to exert a pressure on said member in consequence of the kinetic energy stored in the control element 4whereby the impression of the printing element is eiected by pressure.

'2; In combination with means to propel a type bar to a printing position and a member driven thereby, a velocity control element for controlling the velocity of the type bar, said member and element being provided with complementary and continuous rolling contact surfaces adapted 3. In a typewriting machine, the combination of a pivoted type bar having one edge thereof formed as an unbroken accelerating curve, a key lever, connections between the key lever and the type bar for initiating operation of the latter, a pivoted weight member having an unbroken curved edge including an accelerating curve and a locking curve and mounted in alignment with the type bar, said member and type bar being operatively connected by continuous rolling 'contact between the accelerating curves thereon,so that initial operation of the type bar by the key will actuate 'the weight member with accelerated velocity until the movement of the type bar is brought under control of the locking curve on the Weight member at which point the kinetic energy stored in the weight member becomes effective to cause the weight member to exert operating pressure on the type bar to move the type bar to printing position with greatly reduced velocity and enhanced pressure.

4. In a typewriting machine, the combination of a pivoted type bar, a key lever for initially operating the type bar, an extension on the type bar having an unbroken accelerating curve; and a pivoted control member also having an unbroken accelerating curve which, near the pivot of said member lchanges into a locking curve, said member and type bar being operatively connected by` continuous rolling contact between the said curves so that the operation of a key lever initially moves the type bar toward printing position and simultaneously actuates the control member with accelerated velocity, for the purpose of controlling the speed and force exerted by the type bar at the printing position.

5. A type bar action comprising a segment, a type bar mounted in the segment and adapted to swing in an arc to effect an impression by striking normal to the impression receiving surface, means for operating the type bar to swing the latter in an arc, and a control element pivoted in alignment with the type bar and having a smoothly curved surface coacting with an unbroken edge of the type bar so as to be operated by the type bar by rolling contact therewith and so shaped as to permit a high initial velocity to be imparted to the type bar by its operating 4means with an ultimate rapid deceleration of the type'bar until the velocity of the type bar approaches zero near the printing point, said element being adapted at the printing point to expend on the type bar kinetic energy stored in said elementwherebyto exertsumcient pressure on the type barto effect an impression.

6. A type bar action comprising a type bar, means for operating the type bar adapted to impel the latter toward. a printing position with an initial high rate'of acceleration; and a velocity control element for' regulating the velocity of the typei bar, said element having one edge provided with asmoothly curving outline adapted to have roller contact with the type .bar to be actuated by the latter at a variable rate ranging from zero to a maximum attained when the type bar has reached printing position and also having a heel portion adapted to transfer the kinetic energy stored in the control element to the type bar as a pressure exerted on the type bar at the printing point without substantially changing the velocity vof thetype bar at the printing point whereby to effect the impression by a pressure rather than by percussive impact.

7. An impression control element for type bars of a conventional type which strike normal to the impression receiving surface, comprising a gourdshaped or bulbous weight member provided with a smoothly curved contact portion adapted to coact with the type bar by rolling contact, a narrow pivot portion located at one end of said element with respect to which pivot portion the center of mass is eccentric and provided with a heel portion adjacent the pivot, said heel portion adapted by direct contact with the type bar to transfer to the type bar rotational force due to the inertia of said member.

8. A type bar action comprising a type bar, means for impelling the type bar toward printing position; and a velocity controlling element in alignment with the type bar and having one edge formed with a smoothly curved outline adapted for rolling contact with the type bar whereby the type bar drives said element for a substantial part of the stroke of the type bar toward printing position, the contactual relation between the type bar and element being such that the respective velocities range from zero to a maximum in the case of said element and from zero to substantially zero in the case of the type bar, said element having a portion thereof adapted to contact with the type bar when the latter attains substantially zero velocity to force the type bar against the impression receiving surface with negligible velocity and by ypressure instead of percussive impact.

9. A type bar action comprising a pivoted type bar, means for rocking the type bar on its pivot to impel it toward printing position, and a velocity controlling element pivoted a fixed distance from the axis of rotation of the type bar, an unbroken edge of said element having a direct contactual driving relation to the type bar such that the type bar drives the element with a constantly increasing velocity ratio, said element also having a differently curved portion adapted', when the type bar reaches printing position, to transfer to the type bar the kinetic energy stored in said element. f

10. A type bar action comprising a pivoted printing element adapted to strike a printing surface to produce an impression, said element having an arm smoothly curv'ing radially from a CII point adjacent the pivot of said element to the practically zero velocity when the printing ele- .ment is about to strike the printing surface, said velocity control element having a part thereof adapted to engage the arm when the printing element strikes the printing surface and impart pressure to the printing element to etlect the impression on the printing surface.

11. In combination, a type bar having one edge thereof curving smoothly in an unbroken line, means for initially operating the type bar to propel it toward the point where printing. is effected, and a type bar controlling element having an edge thereof similarly provided with a smoothly curving outline adapted to roll over the curving edge of the type bar when the type is being propelled by the operating means, the smoothly curved edges of said type bar and controlling element being shaped to permit an initial high velocity to be imparted to the type bar by the operating means followed by a rapid reduction in velocity as the type bar approaches the printing point and, finally, to cause the controlling element to -eiect printing by pressure on Athe type bar produced by the kinetic energy stored in the controlling element whileit is being propelled by the operating means.

12. In combination with means to propel a ber actuated thereby, a velocity control element for regulating the velocity of the printing element,`said velocity control element having a smoothlycurving portion engaging the actuated member whereby said element rolls over said member as the printing element is actuated by the propelling means, said velocity control element being adapted to exert a pressure on the actuated member when the printing element reaches printing position to eii'ect the impression by the kinetic energy stored in said velocity control element.

13. An impression control element for controlling the velocity of a printing member comprising a weight having a pivot portion located eccentric of the center ofv mass ofthe weight, a smoothly curving portion adapted to have rolling conta/ct with a part connected to the printing member to regulateits velocity, and a portionh adapted to transfer kinetic energy stored in the weight to the part connected with the printing V. REPPERT.

member. printing element to printing position and a mem-

Images