US 3871506 A
An exchangeable keyboard for ball typewriters, adapted to be employed when the type ball of the typewriter is exchanged for another ball carrying characters which differ in respects other than that of letter type, with the keyboard consisting of indicia-bearing caps which are fitted over the typewriter keys, and including durable, elastic strips extending between the caps so as to bind these together to form an assembled or unitary arrangement.
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Description (OCR text may contain errors)
United States Patent [191 Von Luders 1 Mar. 18, 1975 EXCHANGEABLE KEYBOARD FOR BALL TYPEWRITERS  Inventor: Kirill von Luders, Pohjolankatu 43 A 3, 00610 Helsinki 61, Finland  Filed: Aug. 8, 1973  Appl. No.: 386,742
 U.S. Cl. 197/98, 197/102  Int. Cl B41j 5/08  Field of Search 197/98, 100, 102, 103, 197/4, 36, 37
 References Cited UNITED STATES PATENTS 527,112 10/1894 Harte 197/4 2,435,130 l/1948 Cunningham 197/4 3,290,439 12/1966 Willcox et a1 197/98 X 3,317,019 5/1967 ,Braune 197/98 3,387,693 6/1968 Wirth 197/98 3,507,378 4/1970 Stuckert 197/102 X 3,648,394 3/1972 Hepner 197/102 X OTHER PUBLICATIONS Plastic Keyboard Translater, IBM Techn. Discl.
Bulletin, Vol. 4, N0. 12, May 1962, pp.3-4. Keyboard Transducer," IBM Tech. Discl. Bulletin, Vol. 7, No. 12, May 1965, p. 1170.
Keyboard with Changeable Encoding and Key Designation," lBM Tech. Disc]. Bulletin, Vol. 13, No. 7, Dec. 1970, pp. 2041-2042.
Transfer Tray for Separable Keybutton Caps," IBM Tech. Discl. Bulletin, Vol. 11, No. 4, Sept. 1968, p. 389.
Primary Examiner-Edgar S. Burr Assistant Examiner- E. H. Eickholt  ABSTRACT An exchangeable keyboard for ball typewriters, adapted to be employed when the type ball of the typewriter is exchanged for another ball carrying characters which differ in respects other than that of letter type, with the keyboard consisting of indicia-bearing caps which are fitted over the typewriter keys, and including durable, elastic strips extending between the caps so as to bind these together to form an assembled or unitary arrangement.
4 Claims, 4 Drawing Figures EXCHANGEABLE KEYBOARD FOR BALL TYPEWRITERS 1. Field of the Invention The present invention relates to a keyboard for typewriters and, more particularly, an exchangeable keyboard for ball typewriters.
In effect, the invention concerns itself with an exchangeable keyboard for ball typewriters, adapted to be employed when the type ball of the typewriter is exchanged for another ball carrying characters which differ in respects other than that of letter type, with the keyboard consisting of indicia-bearing caps which are fitted over the typewriter keys, and including durable, elastic strips extending between the caps so as to bind these together to form an assembled or unitary arrangement.
2. Discussion of the Prior Art It is well known in the art that ball typewriters such as, for example, IBM ball typewriters, may be adapted for the typing of characters of varied languages having different alphabets, incorporating Cyrillic, Greek, I-Iebrew, Arabic, Chinese or Japanese characters, mathematical symbols or symbols associated with chemical formulae and the like, by substituting an appropriate type ball suitable for each particular need and purpose. However, the typist is required to know the correspondence between the character on the ball and each respective key on the keyboard. In the prior art it is known to use, for this purpose, separate reference tables which are consulted by the typist, when using a substitute ball, in order to determine the correspondence between the characters and keys. However, the use of such separate reference tables is awkward, involves a large chance of typing errors being made, and considerably lowers the speed of the typing.
Exchangeable keyboards of the type mentioned hereinabove are known in the prior art, for instance, from US. Pat. Nos. 527,112 and 3,317,019. In these earlier patents, however, the problem of interconnecting the caps and the strips interconnecting the former has not been satisfactorily resolved.
SUMMARY OF THE INVENTION It is, accordingly, an object of the invention to eliminate the drawbacks encountered in the prior art by providing an exchangeable keyboard in which the caps are formed of two parts, in effect, a cap body portion and a hat or cover portion mounted thereon, with a connecting strip passing along each row of keys uninterruptedly through the entire key row, and with the strip being fastened to each cap intermediate the cap body portion and the hat or cover portion.
The use of typewriter key caps which are detached from each other is unsatisfactory since their mounting on the keys, one by one, would be much too time consuming. In contrast thereto, when the caps are mutually joined so as to form an entity or assembly, by means of durable, elastic connecting strips extending therebetween, and which extend, for instance, uninterruptedly along each row of keys for the full length of the key row, the entire keyboard may be adjusted or converted into position, row by row, within a few seconds. Advantageously, the extreme left end keys in each row may be mutually joined by a similar connecting strip so that parallel key rows are linked together at their left-hand margins whereby the whole keyboard forms an entity.
This will also ensure that the installation or overlay of the entire replacement keyboard is automatically attained in the correct sequence and order.
BRIEF DESCRIPTION OF THE DRAWINGS The present invention is now described in greater detail, having reference to the accompanying drawings, in which:
FIG. 1 illustrates in a perspective view an exchangeable replacement keyboard according to the invention shown installed in a typewriter;
FIG. 2 shows, in an enlarged scale, a fragmentary portion of a row of keys fitted with replacement keys including the caps and connecting strips according to the invention; and
FIGS. 3a and 3b respectively show details of the cap and strip of the exchangeable replacement keyboard.
DETAILED DESCRIPTION The exchangeable overlay or keyboard, as illustrated in FIGS. 1 and 2, comprises caps 1 formed of thin plastic foil which are dimensioned so as to closely conform to the respective keys 5 of the typewriter. Between the caps 1 in each row there extends a continuous ribbon or strip 2 made of a very tough, durable and exceedingly thin plastic which interconnects the keys in each row to form an assembly or single entity while still permitting relative motion between the individual keys so that when a given key is depressed the adjacent keys will not move along in conjunction therewith.
Each of the caps 1 consists of two parts, a cap body portion 3 and a hat or cover 4 superimposed thereon. The strip 2 connecting the caps is located so as to extend over the entire length of the key row so as to pass between the cap body portion 3 and the hat portion 4 of each respective key so as to be clamped therebetween.
Since the strip 2 is formed of a tough, durable, and flexible material, this concurrently implies that its gluing properties are generally poor. Consequently, it is most advantageous to fix the strip 2 through a formfitted attachment between each cap body portion 3 and hat or cover 4, as illustrated, for example, in FIGS. 3a and 3b. In FIG. 3a the strip 2 is illustrated as having been provided with notches 6 having a shape in conformance with the contour of a depression 7 formed in the inner surface of the hat or cover 4, as shown in FIG. 3b from the lower side. It is possible to produce notches 6 in the strip 2 by punching, and also at the same time it is quite advantageous to make the whole stip by punching, in which case it may be formed so as to have the curving shape shown in FIG. 3a, thereby making it possible to compensate for the slope of the key top face so that the fold between adjacent keys formed by the strip 2 will extend in a direction in conformance with the direction in which the keys are adapted to move.
The various key rows of the keyboard may furthermore be connected along the left end edge of the keyboard by means of similar ribbons or strips 2a, in view of which the whole exchangeable keyboard forms a single entity or assembly. It then becomes possible to rapidly snap on the keyboard, first by placing the key caps at the left-hand end in their proper positions and then sequentially positioning the key caps of each row over the respective keys of the typewriter, row by row. The strip 2 preferably is fastened to the caps proximate to their upper portions, whereby the folds of the strip 2,
which are necessary so as to permit for the relative motion or depression of the keys, is suitably disposed in the spaces between each of the keys.
The new symbol or indicia for each respective key is provided either on a separately printed film and then positioned below the transparent hat or cover 4, or alternatively may be printed on the inside of the upper surface of the transparent hat 4. However, preferably, the hat or cover is formed of the same material as the original typewriter key it covers and the new symbol or indica is printed or embossed on the hat in the same manner as on the original typewriter key.
Although according to the drawing the side walls or skirt edge of the cap does not extend completely down to the lower edge of the key, in an advantageous and practical embodiment the skirt extends slightly past the lower margin of the key so as to thereby provide a positive attachment of the exchangeable or replacement keyboard. However, the attachment of the individual caps to their respective keys should not be unduly firm in order to make it possible to detach the whole keyboard by means of a single pull.
While there has been shown what is considered to be the preferred embodiment of the invention, it will be obvious that modifications may be made which come within the scope of the disclosure of the specification.
What is claimed is:
1. In an exchangeable keyboard least one ball typewriters, adapted for use upon the type ball of the typewriter being exchanged for another ball having indicia or characters thereon which differ from that of the first-mentioned ball, said keyboard including a plurality of caps adapted to be superimposed on respective of the typewriter keys, and at leastone durable elastic strip extending between adjacent ones of said caps so as to interconnect the latter into a single entity; the improvement comprising said caps each including a cap body portion, and a cover portion mounted on said body portion, said strip continuously extending along each row of keys for substantially the full length of the key row, said strip being fastened to each said cap intermediate the cap body and cover portions, notches formed in said strip, said strip being engaged in a form-fit attachment between each said cap body and cover portions in the region of said notches.
2. Exchangeable keyboard as claimed in claim 1, said cap cover portion being transparent, film means being positioned in said cap below said cover portion, and indicia or characters being printed on said film means in conformance with the indicia or characters on said other type ball facing upwardly toward said cover portion.
3. Exchangeable keyboard as claimed in claim 1, said cap cover portion being formed of material essentially similar to that of the keys on the typewriter keyboard, and indicia or characters being imprinted on the upper surfaces of said cover portions in correspondence with the indicia or characters provided on said other type ball.
4. Exchange keyboard as claimed in claim 1, comprising at least one said strip interconnecting caps of adjacent rows on said keyboard along one edge of said typewriter.