US2307164A - Typewriting machine - Google Patents

Description

Jan. 5, 1943. .1. F. SMATHERS 2,307,164

TYPEWRITING MACHINE Filed Oct. 15, 1940 ATTORNEY.

Patented Jan. 5, 1943 aim-1p STATES PATENT oF'FlcE mnwmmo MACHINE James F. Smathers, Rochester, N. Y., assignor to international Business Machines Corporation, New York, N. Y., a corporation of New York Application October 15, 1940, Serial No. 361,208

2 Claims. (Cl. 197-35) This invention relates to typewriting machines.

The object of the present invention is to provide an improved type bar.

An object is to provide a type bar which is quieter in its operation than type bars now used in the art.

An object is to provide a type member in which the type element is movably mounted.

An object is to provide a type bar having a resilient construction in the head.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawing, which discloses, by way of example, the principle of the invention and the best modes, which have been contemplated, of applying that principle.

In the drawing:

Fig. 1 is a side view of one form of the type bar.

Fig. 2 shows a modification.

In Fig. 1 there is shown a form of type bar which, it has been found, is much quieter than the usual type bars of present commercial machines. The type bars as now used in the art invariably consist of a solid blank of suitable shape to the end of which is secured a type element 5 having upper and lower case characters 5a and 5b respectively. Such type bars are pivoted on the well known wire segment so as to swing in an arc of approximately 90 before striking the paper through the usual ribbon. Ordinary type bars are extremely noisy and efment 5 is in effect resiliently mounted on the end I of the type bar and is capable of a very limited yielding movement when the type strikes the paper through the ribbon.

The curved portion 4 extends to the left toward the opposite end of the type bar to form the usual aligning lug B which cooperates with the type guide to hold the type bar steady against lateral vibration at the printing point. Near where the curved portion 4 joins the body of the type bar, below the stop portion 3b, there is provided a collide lug I which prevents defacing of the characters 5a, 5b in the event of a collision between two type bars. The type bar is also provided with a long longitudinal slot 8, beginning near the center of the bar and extending close to the end of aligning lug 6 to give the type bar greater resiliency between the points where it strikes the anvil and the paper, respectively. An anvil stop lug 9 is provided which strikes the usual anvil.

The type bar shown in Fig. 1 may be propelled by any well known means but is particularly well suited to power operated typewriters in which the type bars are operated by some form of power means and the keys merely control the opforts to quiet them have not been completely successful. Efiorts to quiet the type bar have been centered on providing platens which have a tendency to absorb sound, as by providing thick soft rubber facings for the platen or a soft .rubber base for the platen surface, or by modifying the internal structure of the platen. However, the problem cannot be solved by using a softer platen because it quiets the noise of the type bars at the expense of clear type impressions, the platen then being too soft and permitting the type bars to emboss the paper. With the present invention, an ordinary hard platen or one with a medium surface may be used which is hard enough to give a clear impression.

As shown in Fig. 1, the head of type bar 3 is formed with a bulbous slot 3a to produce a reversely curved resilient portion 4 to which is secured the type element 5, as by soldering in the usual way. The curved portion 4, adjacent the left hand character 5b of the type element 5, is spaced from a stop portion 3b, formed in the head of the type bar, by a gap 4a which may be between .005" and .010", whereby the type eleeration of the power means. An example of such a machine is the well known Electromatic typewriter, which has also been known as the International. In power operated typewriters, the force of the blow exerted by the type bars is considerably greater than in manual machines, consequently, the noise is very distracting when the type bars and platens commonly employed in the art are used.

When the type bar 3 is close to the printing point, the anvil lug 9 strikes the anvil before the type characters 5a or 5b strike the ribbon. Thereafter the slotted end of the type bar flexes between the anvil lug 9 and the platen suinciently to allow the type element to strike with a whipping action which insures a clear sharp impression of the characters through the ribbon. After the type bar 3 strikes the anvil, the type character or 5b is obstructed by the platen, and then the kinetic energy of the type bar causes the gap 411 between the curved portion 4 and the stop portion 3b of the type bar to close.

As a result of the provision of the gap 4a, it has been found that the type bar actually is very much quieter than type bars most commonly used, owing, apparently to the fact that the final impression force is by a spring action through the resiliently curved portion 4 rather than by a solid blow. .Due to the small size of the gap and the resiliency of the curved portion 4!, no noise. results from the closing or the gap but, nevertheless, there is sumcient spring pressure to quiet the blow and produce an even impression.

In Fig. 2 there is shown a modified form which operates upon the same principle but in this case, the curved portion at Fig. i. which is free at one end, is replaced by a curved resilient bridge portion It). This resilient bridge portion IE3 is formed by a. continuation 8a of the slot 8 to the head of the type bar behind type element 5 so that the slot a, with the hook-shaped extension 80., is hooked or C-shaped to give maximum resiliency to the bridge portion iii. The extension 80. of slot 8 is constricted or reduced in width immediately behind the type element 5 to form a stop gap for the stop 312. Thus the type element 5 is resiliently supported at both ends instead of at only one end, whereby the type element 5 of Fig. 2 can yield in more nearly a straight line instead of moving in an are as in Fig. i.

In blanking both of the above type bars, sufficient metal is left adjacent the stop portion 3a to insure suificient kinetic energy to close the gap when the type element strikes. The gap in Fig. 2 may be the same in dimension as in Fig. 1.

While there has been shown and described and pointed out thefundamental novel features of V gitudinal slot extending from the anvil contact-,

ing portion of the type bar into the head of the type bar; said slot being formed hook-shaped adjacent the type element and curving away from the type element to provide a curved resilient bridge in the head to support the type element, said slot also being constricted behind the type element to form a gap which is closed upon impact of the type element.

2. A. type bar having a head, a type element, an anvil contacting portion intermediate its ends. and a type element supporting portion at one end; said type supporting portion being part of a curved bridge formed by a curved slotwhich extends from a point substantially close to the anvil contacting portion and into the head and is reversely curved behind the head toward the anvil contacting portion to provide a high degree of resiliency in the type supporting portion, said slot being constricted adjacent the type element

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