US2153720A - Noiseless typewriter - Google Patents

Description

April 11, 1939. R. LEVI uoxsmmss TYPEWRITER Filed July 14, 1936 2 Sheets-Sheet 1 RICGARDO LEVI wj w w *JW April 11, 1939. R. LEVI NOISELESS TYPEWRITER Filed July 14, 1936 2 Sheets-Sheet 2 Ia/ante;

RICOARDO LEVI. V

Patented Apr. 11, 1939 PATENT OFFICE "norsnuiss mnwnrrna -.Riccardo .Levi, "I'orino, Italy, assignor -to the s Firm Q. Olivetti & 0., Ivrea, Italy In 1m; July 16, 1935 ApplicationfJuly 14, 1936, Serial No. 30,602

scum. (01. 197-31) Itis well known that in ordinary-typewriters the typeszhave an impression surface which is disposed at right angles to the plane or movement of the type barswhich carry them. In the fol- 5 lowing description'the word type" designates 'the' metal partwhich in most cases carries. two characters. These types are, however, secured to type bars with which they form a given angle, namely the same angle as the type bar itself makes with the plane of symmetry of the machine.

This angle is obtained by bending or twisting the end of the type bar or by providing the type with a pin which is welded to the type bar in such a manner as to form the desired angle. In all previous constructions for obtaining this angle, the body of the type is, however, always arranged out of the plane of the type bar, where by the lateral space requirements are increased. In the middle the space requirement is equal to the breadth of the type, whilst it increases towards the sides and for an angle of 90 is equal to its length. It must also be taken into consideration that. the type, or the part which carries it, is usually provided with an extension the purpose of which is to engage in a central guide which is consequently known as the type guide. For this reason its length is in practice greater than the extent of the characters which it carries. On account of this increase in effective size, ordinary machines also have from the middle towards the sides greatly increased angular distances between each pair of adjacent type bars. Then also, due to the necessity of providing the machine with a large number of characters, use is made of the fact that the adjacent types, in spite of their gradually increasing inclination relative to the type bars which carry them, extend practically parallel to each other.

The present invention, which is chiefly applicable to noiseless machines, is essentially characterized in that the type or a part secured thereto by welding or the like is not rigidly connected to the type bar, but is pivotally connected to the head of the type bar in such a manner that, when in the rest position, it lies in the same or almost the same plane as the type bar, but, when in the writing position, it assumes the inclination necessary therefor. This is attained in that the type performs a progressive pivotal movement relatively to the type bar, which movement takes place during and as a result of the movement of the type bar. The movement of the. type relative to the type bar must commence with a velocface 6. A suitable head I, which may have the form of a nut or of a washer and is as easily ity, which is initially equal to zero or is very small, in order that the space required by the type should not in practice exceed its breadth shortly after leaving the rest position.

A preferred constructional form of the present invention is illustrated by way of example in the accompanying drawings in which:

Fig. 1 is across-section through the part which .carries the type bar, taken in the plane of movement of a lateral typebar, the actuating mecham nism of which is not shown,

Fig. 2 is a cross-section at right angles to that shown in Fig. l and shows the type bar ,"in the rest position,

Fig. 3 illustrates a lateral type bar and its type in" the writing position viewed from the direction of the platen, V

Fig. 4 illustrates details of the mounting of the type and of the guide members on the type guide means, and

Fig. 5 illustrates the actuating mechanism for a moving unit near the middle, in which the angle of pivotation of the type is small.

Iii-Figures 1 and 5 the rest position is illustrated 1:1 full lines and the writing position in dotted l nes.

The type bar I is pivotally mounted on an arcuate wire 2 arranged in a fixed bearing member I3 and is guided in slots in the said bearing member. The type bar is provided at its head with a thickened part which forms a pivot hearing for a pin S-connected with the type carrier 5 (Fig. 4). The type 4 is secured to the type carrier 5 by welding. Thus the type I can pivot about the axis of the pin 3 relatively to the type bar I.

The writing pressure is transmitted from the type bar to the type at the plane supporting surremovable as possible, prevents the type carrier 5 from becoming detached from the type bar I. The type carrier 5 in the rest position lies against a projection '5I on the type bar I and is connected by a pin 8 to a pushrod 9 which is in turn connected by means of a pin ID to a slider II (Figs. 1, 2 and 3) which slides in a slot I2 in the type bar I. As can be seen from Fig. 2 the pin III is arranged at the opposite end 'of the rod 9 to the pin 8 and at right angles to the type bar, in such a manner that, even in the rest position there is an adequately long lever arm relative to the pin 3 for effecting the pivotal movement of the type carrier 5 and the type 4. In other words the type carrier 5, the push rod 9 and the slider II form a non-concentric crank mechanism (since the pin III does not move axially) if the type bar I is regarded as a fixed support, the type carrier as a crank, the push rod 9 as a push rod and the slider II as a sliding shoe. In this crank mechanism the slider II is the force imparting member.

' In order to effect the displacement of the slider I I, there is provided in the fixed bearing member I3 a further arcuate wire I4 which is bent about the same axis as the wire 2, is disposed in a plane parallel to that containing the said wire 2 and has a diameter of curvature greater than that of the said wire 2. In the recesses in the bearing member I3, which serve for guiding the type bars I, there are also arranged for movement levers I5, which however are also pivotally mounted on the wire It already mentioned. A bell crank lever I1 is pivotally mounted on the type bar I by' means of a pin I5 and is connected at one end to the lever I5 by a pin' I8 and controls the movement of a pin I! by means of a fork at its other end, which pin I9 is in turn secured to the slider II. In order to explain the manner of operation of this arrangement, it must first of all be assumed that the type bar I is stationary while the bearing member I3 rotates relatively to it. The bearing member may then be regarded kinematically as a crank arm which is pivotally connected to the type bar I at 2 and is of a length equal to the distance separating the wires 2 and I4. The bell crank lever I1 is pivotally mounted at I5, acts as a driven crank and is connected to the driving crank by the lever I5 which acts as a push rod. It is clear then that the pivotation of the said crank arm between 2 and I4 brings about the rotation of the crank I1 which moves the slider I I by means of the pin I9. This causes in turn a corresponding rotation of the type 4.

The movements described above, which are brought about by the pivotation imparted to the crank arm between 2 and I4, are in fact produced by the pivotal movement of the type bar I. In this way each position of the type bar I corresponds to an accurately determined position of the type. Since at the commencement of the movement the points 2, I4 and I8 lie in or nearly in a straight line, the initial velocity of the lever II in its movement relative to the type bar I as well as the initial angular acceleration of the type are qual or nearly-equalto zero. Thus the requirement is fulfilled that the type is disposed, not only when in the rest position but also when it is near that position, in aplane which is the same or nearly the same as that of the type bar which carries it. There is arranged for longitudinal adjustment in the slot I2 an abutment 20 which provides for the slider II or any desired part'connected thereto a definite adjustable end position in order to enable the angle of pivotation of the type to be adjusted and to cause this rotation to finish somewhat before the end of the movement of the type bar I. Since, however, the elements described form a definite kinematic chain, this premature cessation of movement necessitates'the inclusion of a resilient member in the chain so that'the type bar I can move still further, although the relative movement of the type has already ended.- This resilient member may for example have the form of a spring 2I,

which resiliently connects the pin I8 to the lever I5. The pin I8 may slide in a longitudinal slot in the'lever I5, but is normally held back by the spring 2|. When. however, the slider II comes ,as small as possible.

to rest against the abutment 20, the spring 2| stretches so as to permit of a kinematic lengthening of the lever I5 and at the same time the further angular movement of the type bar I.

The pivotalmovement of the type must increase from the middle, where it is practically nil, towards the sides of the machine. The arrangement described makes this possible in a simple manner in that only the position of the pin I6 of the bell crank lever relative to the type bar I and to the ends of the bell crank lever need be altered. In other words the parts which are necessary for the pivotation of the individual types differ only in the lever transmission mechanism, which can be altered merely by varying the positions of the pin I6 and the abutment 20.

In the zones near the middle, however, the pins I6 must be disposed closer to the pins IS in order to cause a very small movement of the slider II and at the same time a very small pivotal movement of the type. In this case (Fig. 5) the lever I'I may be replaced by a lever 52 which is pivotally connected to the lever I at a point I6 ,removability already referred to of the head 1 and also because the guide slot I2 is provided with an enlarged part 22 at one end which is never reached in practice by the slider II during its movement, which part 22 permits the head of the guide pin of the slider II to pass through.

It is here recalled that the invention is concerned chiefly with noiseless machines, in which, as is well known, the writing is produced by means of the static pressure of a system of toggle links or other similar devices. The following description is concerned with the principal of these toggle links which co-operate directly with the typebar.

The types are each provided with two characters, one for the small letters and the other for the capitals. The connection of the principal toggle link with the type bar cannot lie in the axis of pivotation of both characters. The impression of the type against the roller produces an opposite pressure which does not pass through the pin 44 which connects the principal toggle link to the type bar (Figs. 4 and 5) and consequently produces a moment. In Fig. 4, the principal toggle link is connected in the middle between the two characters so that this moment is It acts, however, in both directions. If, instead of this, the connection were provided in the axis of one of the characters, e. g., of the small letter, the arrangement would have the advantage of being able to obtain a moment only when the pressure is applied to one of the capitals, but this moment is doubly large. To return to the case illustrated in Fig. 4, the moment is equal to the product of the writing pressure and half thedistance between the small letter and the capital (usually 3.3

Due to this arrangement the resultant of the forces, which act upon the moving mechanism, passes through the axis of the pin 3 of the type and is resolved into a pressure acting along the toggle link and a tractive force acting along the type bar I.

It is obvious that the arrangement of the pin .and recess on the type carrier 5 and type guide 21 correspondingly forms only one constructional example by means of which the problem can be solved, since the moment referred to can also be taken up from a fixed part by other means. in so far as these means constitute vertical supports which are consequently at right angles to the main force. It can also easily be seen that the vertical supports completely fulfil their purpose without moreover weakening the main writing r force, but by a component of friction. Since the horizontal distance between the two supports can be very much greater than thelever arm (3.3 mm.) of the moment, the pressure and the corresponding frictional loss are very small. Finally the wear of the type guide 21, to which as has already been explained very little pressure is transmitted, cannot cause either alteration in the spacing or in the even level of the writing. This wear acts only as a reduction of the stiffness of the movable system, that is to say it reduces the writing force.

It is also clear that the noiseless operation of the type causes neither a reduction in the writing speed nor an increase in the initial velocity and consequently an increased finger pressure as compared with ordinary machines which operate by impact. This holds good, if the dis-' tance which has to be covered by the type is equal in both machines. If, however, this distance can be reduced, this disadvantage is reduced or avoided or the noiselessness-as compared with ordinary machines is even improved upon. As regards the ability of the type to pivot, the space required from the middle to the sides is none the less constant, that is to say it is never greater than its actual breadth. Consequently the total space requirement of all the types is much smaller than in a machine with fixed type, and at the same time, if the angle between the lateral type bars and the axis of symmetry of the machine and the'angle of pivotation, e. g. are both equal, the length of the type bars in the machine according to the present invention.

is much smaller than that in machines with fixed type. The shorter type bar has a shorter stroke and a smaller mass to be displaced-and consequently produces a soft operation of the mach ne. It also follows that a further essential advantage of the machine according to the present invention is the possibility of reducing the length of the type bar and of making the touch more gentle. These advantages are especially important in noiseless typewriters the touch of which is, for other reasons already mentioned, worse than that of ordinary machines. Finally the reduction of the distance ,through which the type moves results in a reduction both in the space required and also in the distance to be travelled by all the parts interposed between the keys and the type bars, so that constructions are possible which were formerly impossible to carry out because of the large amount of space necessitated. It is thus made possible, to select a'particularly suitable construction, which is described with refercnce to Fig. 5 as a constructional example of the invention.

The key lever 24, which is pivotally mounted,

means of a connecting link 32 which is pivotally connected by pins 3I and 33 to the levers 28 and 34 respectively. The intermediate lever 34 is pivotally mounted in the frame 30 of the machine by means of a horizontal wire 35, which is parallel to the wire 29 on which the key lever is mounted. The distances are so chosen that at the end of a stroke (as shown in dotted lines) the axes of the pins 3I', 33 and of the wire 35 lie in a straight line, and thus form a rigid and noiseless stroke limit for the key lever 28. The transmission ratios between the levers 28 and 34 are so chosen that, if the strokes of the keys in all rows of keys are equal, each intermediate lever 34 will rotate an equal amount. In this way a universal bar 36, which is pivotally mounted at 3'! and cooperates with the levers 34, always rotates through the same angle, the movement being always derived from the said key. Consequently the part of the universal bar against which the levers 34 act may be made rectilinear, which results in a particularly simple constructional form. The universal bar 36 serves in known manner for causing the travel of the carriage and the movement of the ribbon.

The lever 34' cooperates directly with the push lever 38 which forms the first part of the main toggle link which actuates the type bar I. The transmission between the levers 34 and 38 is effected by means of a spherical pin 33. The levers 38 are pivotally mounted on a wire 40 which is arcuate and extends parallel to the wire 2 of the type bar I. Thus the intermediate levers 34 are of unequal length and since, as has already been explained, they all rotate through the same angle, their pins 39 travel different distances.

Nevertheless all the push levers 38 rotate through the same angle since the pins 39, which they move through forks 4I, act on lever arms which are diflerent to suit the lengths of the lever arms betwen 35 and 39. This transmission from the key levers to the push levers has the following advantaeesz- 1. The possibility of making use of a rectilinear universal rod.

2. The possibility of making all the key levers 28 of any one row and the connecting links 32 and push levers 38 of the whole machine equal in length.

Other systems designed to attain the same ends do not possess the above advantages.

The push levers 38, which are actuated from the keys by the mechanism described above, drive the type bars I through the connecting links 42 which are pivotally connected at 43 to the push lever 33 and at 44 to the type bar I (see also Fig. 4). The same lever 38 also actuates an inertia mechanism the first part of which, the link 45, is pivotally connected at 46 to the lever 38 which finger already has to accelerate the type bar in order to move it from the rest position to the proximity of the writing position. In asecnd phase it must receive the energy which the lever and type have previously had imparted to them, in order to retard the movement of these parts, so that the type itself is pressed with the smallest possible velocity against the paper, thereby attaining a noiseless contact. In a third phase the inertia mass 50 has to restore the energy previously imparted to it in the form of static pressure, which is exerted through the extended position of the toggle mechanism, for the necessary writing force. The construction described seems to be particularly advantageous in this respect. During operation the link 35 is first of all in the starting position and shortly after, the momentary axis of pivotation is close to the centre of gravity of the mass 50 which thus has a minimum velocity (phase I). When the type bar has had imparted to it by the main toggle link its highest velocity, the momentary axis of pivotation and the centre of gravity of the mass 50 move rapidly apart (phase II). Finally, the mass 50 tends thereafter to bring the three pins l8, l1, 49, together with the three pins 40, 43, 44 into a straight line (phase III).

A spring 53, which has to return the whole moving mechanism to the starting position, is secured to the lever 48. Thus it exerts the greatest force at the commencement of the return movement, so that it can move the toggle link out of the extended position. Furthermore, in this way the return is accelerated and the danger of the type bar sticking in the type guide due to friction is avoided. Obviously the spring may be arranged in another position and may be secured to other suitable parts of the moving mechanism.

I claim:

1. A typewriter comprising a frame, a type bar pivotally mounted on said frame, a type carrying member pivotally mounted on said type bar about an axis substantially tangential to the circle of movement thereof and arranged to lie substantially parallel to said type bar when said type bar is in the rest position, means for actuating said type bar, and a lever system connected between said type carrying member and said frame for causing said type carryin member to rotate during movement of said type bar into the correct position for writing.

2. A typewriter comprising a frame, a type bar pivotally mounted on said frame, a type carrying member pivotally mounted on said type bar about an axis substantially tangential to the circle of movement thereof, and arranged to lie substantially parallel to said type bar" when, said type bar is in the rest position, means for actuating said type bar, and means connected between said type carrying member and said frame for causing said type carrying member to rotate during movement of said type bar into the correct position for writing, said last mentioned means including a slider slidably mounted on said type bar, a push rod connected between said type carrying member and said slider and means connected between said slider and said frame for causing said slider to move when said type bar is actuated.

3. A typewriter comprising a frame, a type bar pivotally mounted on said frame, a type carrying member pivotally mounted on said type bar about on said slider, a forked bell crank lever pivotally mounted on said type bar, the forked end of said bell crank lever engaging with said pin, a lever pivotally mounted on said frame about an axis near the axis of pivotation of said type bar and pivotally connected with the other end of said bell crank lever.

4. A typewriter comprising a frame, a type bar pivotally mounted on said frame, a type carrying member pivotally mounted on said type bar about an axis substantially tangential to the circle of movement thereof and arranged to lie substantially parallel to said type bar when said type bar is in the rest position, means for actuating said type bar, and adjustable means connected between said type carrying member and said frame for causing said type carrying member to rotate during movement of said type bar into the correct position for writing.

5. A typewriter comprising a frame, a type bar pivotally mounted on said frame, a type carrying member pivotally mounted on said type bar about an axis substantially tangential to the circle of movement thereof and arranged to lie substantially parallel to said type bar when said type writing, said last mentioned means including a slider slidably mounted on said type bar, a push rod connected between said type carrying mem ber and said slider, adjustable means for limiting the path of movement of said slider and means connected between said slider and said frame for causing said slider to move when said type bar is actuated.

6. 'A typewriter as claimed in claim 5 and comprising resilient means connected between said slider and said frame for enabling said type bar to continue movement after said slider has come to rest against said adjustable limiting means.

'7. A typewriter comprising a frame, a type bar pivotally mounted on said frame, a type carrying member pivotally mounted on said type bar about an axis substantially tangential to the circle of movement thereof, and arranged to lie substantially parallel to said type bar when said type bar is in the rest position, means for actuating said type bar, and means connected between said type carrying member and said frame for causing said type carrying member to rotate during movement of said type bar into the correct position for writing, said last mentioned means including a slider slidably mounted on said type bar, a push rod connected between said type carrying member and said slider, an adjustable stop on said type bar for limiting the path of movement of said slider, a mechanism connected between said slider and said frame for causing said slider to move during movement of said type bar, said mechanism comprising a pin mounted on said slider, a bell-crank lever pivotally mounted on said type bar, said bell-crank lever having one arm connected to the pin on the slider, a link pivotally connected at one end to the other end of said bell-crank lever, and a pivot connecting the other end of the link to the frame.

8. A typewriter comprising a frame, a type bar pivotally mounted on said frame, a type carrying member pivotally mounted on said type bar about an axis'substantially tangential to the circle of movement thereof, and arranged to lie substantially parallel to said type bar when said type bar is in the rest position, means for actuating said type bar, and means connected between said type carrying member and said frame for causing said type carrying member to rotate during movement of said type bar into the correct position for 'writing, said last-mentioned means including a slider slidably mounted on said type bar, a push rod connected between said type carrying member and said slider, an adjustable stop on said'type bar for limiting the path of movement of said slider, a mechanism connected lm said slider, a bell-crank lever pivotally mounted on said type bar, said bell-crank lever having one arm connected to the pin on the slider, a link vpivotally connected at one end to the other end of said bell-crank lever, and a pivot connecting the other end of the link to the frame, the pivot about which the type bar moves; the pivot connecting the link to the frame and the pivot connecting the link to the bell-crank lever being in alignment when the type bar is in the position of rest, so that at the begimiing of movement of the type bar from its position of rest the bellcrank lever remains practically immovable relative to the type bar whereby the slider and type carrying member remain substantially immovable relatively to the type bar.

RICCARDO LEVI.

Images