US2615549A - Keyboard key - Google Patents

Description

Oct. 28, 1,952 c K, MARLQW 2,615,549

KEYBOARD KEY I Filed Oct. 28, 1949 FIE-z INVENTOR. FIE- E CHESTER K. MARLOW Patented Oct. 28, 1952 KEYBOARD KEY Chester K. Marlow, Oakland, Calif., assignor to Friden Calculating Machine 00., Inc., a corporation of California Application October 28, 1949, Serial No. 124,095

Claims.

This invention relates to an improved means of securing a control key'to a keyboard key stem, and more particularly to a means of pressure fit ting a relatively heavy but slightly elastic control button to the associated key stem of a business machine or the like in such a manner as to produce at normal room temperatures a bond which will effectively resist forces tending to separate the finger button from the key stem during continued high speed operation of the keyboard.

In the construction and operation of automatic calculators, typewriters, and other similar machines, it frequently is desirable to return the control keys to their inactive or fully raised position as rapidly as possible, while at the same time enhancing the general appearance of the keyboard by providing control buttons having a shape and configuration adapted to conceal from view as much of the upwardly extending key stems as possible. This practice frequently increases the mass of the individual key assemblies to such an extent that keystones and other conventional securing means are not entirely satisfactory in preventing relative movement or separation between each such control key and its associated key stem, particularly in instances wherein it is desirable to directly apply resilient pressure to the base of each control button in order to accelerate the upward movement of each individual key assembly during release. The problem of establishing an elfective bond between such a control button and its associated key stem becomes even more difficult to solve when the keyboard must be operated at relatively high speeds for prolonged periods while being at the same time subjected to higher than normal operating temperatures.

It is an important object of the present invention to provide a means of effectively securing a slightly elastic and relatively heavy control button to the corresponding keyboard key stem of a business machine or the like in such a manner as to produce an effective bond therewith, even though such a control key must be rapidly decelerated at the end of each high speed release operation.

It is also an object of the instant invention to provide a means of establishing at normal room temperatures an effective bond between a relatively elastic keyboard control button and its ssociated substantially inelastic key stein as a result of the application of downwardly directed pressure tending to press or force fit the button onto the key stem.

It is another object of the present invention to form a self-locking means for securing a relatively heavy plastic control button to its associated key stem in such a manner as to produce an effective bond and to substantially prevent relative movement between the button and the key stem whenever each such key assembly is frequently and repeatedly decelerated rapidly during release while being at the same time subjected to resilient pressures tending to separate the control button from its associated key stern.

It is still a further object of this invention to produce a means of eilectively securing a slightly elastic control button to relatively inelastic keyboard key stem in such manner as to establish a self-locking shear engagement therewith, which engagement is particularly adapted to eifectively resist intermittently induced inertial forces tending to release the same and tending to cause a progressive separation of the control button from the key stem whenever the keyboard is operated at elevated temperatures for pro longed periods and at high speeds.

Further objects are to provide a construction of maximum simplicity, economy and ease of assembly and disassembly, also such further objects, advantages and capabilities as will fully appear and as inherently possessed by the device and the invention described herein.

The invention further resides in the combination, construction and arrangement of parts illustrated in the accompanying drawings, and while there is shown therein a preferred embodiment thereof, it is to be understood that the same is illustrative of the invention and that the invention is capable of modification and change and comprehends other details of construction without departing from the spirit thereof or the scope of the appended claims.

Referring to the drawings:

Fig. l is a plan view of a typical keyboard. key assembly embodying the instant invention.

Fig. 2 is a transverse cross-sectional view taken along the lines 2-2 in Fig. 1.

Fig. 3 is a longitudinal cross-sectional view taken along the lines 3--3 in Fig. 1.

Referring now more particularly to the drawings, in which like reference numerals indicate like parts in the several views, there is shown a keyboard key assembly for an automatic calculator, typewriter, or similar business machine, which assembly includes a relatively elastic control button 20 adapted to be pressed onto and retained in self-locking engagement with the similarly formed top portion 22 of a substan- 3 tially inelastic key stem 23. This manually depressible control button 20 is molded or otherwise formed of a thermo plastic material, such as a suitable vinyl or polystyrene resin, which is slightly elastic and has limited flow characteristics when subjected to pressure at normal room temperatures. Button 20 may be of modified cylindrical shape and of a generally elliptical cross section having flattened end portions 24 as illustrated in Fig. 1, or the keyboard control buttons may be of circular or other suitable cross section, if desired. A plastic inlay 25 in the form of a suitable identifying numeral or letter is cemented, molded, or otherwise embedded within the upper contact surface 2| of each button, and

inlay 25 preferably is formed of a suitably colored plastic which will provide a pleasing visual contrast with the background color of the control button 20. 1

Key stem 23 preferably is punched or pressformed from a relatively thick and rigid sheet of metal, and has a rectangular, round, or other suitably shaped aperture 26 disposed centrally therein-at a convenient distance below the uppermost surface 2'1 of control button 20. Key stem,

23, preferably but not necessarily, has a shoulder 28 extending inwardly from the opposing vertical a seat for the button 2|] when the top portion 22 of the key stem is pressed into engagement with the coacting recess molded or otherwise formed interiorly within button 23. In some applications, however, it may be desirable to elirni nate the shoulder 28 so that the top portion 22 of the key stem has a lateral dimension substan-,-,

tially equal to the distance between the opposing vertical edges 29 thereof, in which case the vertically disposed interior slot or recess 30 is formed within button 20 so that the top surface 21 of key stem 22 seats against the coacting interior hori-;

zontal surface 3| of recess 3|). Thus, the configu ration of the interior cavity or recess 39 in the control button 20 is substantially the same as but slightly larger than the coacting top portion 22, so that the latter will normally be received in a close running fit or in sliding engagement therewith.

Means is also provided for securely retaining the relatively heavy control button 20 in a predetermined position on key stem 23 and in efiec-, tive self-locking engagement therewith, even" though resilient pressure of considerable magnitude is continuously applied to the; lower surface of the button for the purpose of accelerating the upward movement and causing a rapid release, of the key assembly from its depressed positioni Referring now to Fig. 2, it will be apparent that the thickness of the recess 3i) formed interiorly within button 20 is equal to or only sli htly greater than the thickness of key stem 23, and,

.that a resilient clip or rodlike spring member has been interposed therebetween. This .clip preferably is of round cross-section and is formed of spring steel, piano wire or similar resilient wire having a diameter sufiiciently greater than the,

of square cross-section, if desired. The length edges 29 thereof, which shoulder preferably forms of clip 35 is substantially equal to the distance between the top surface 21 of the key stem andv the uppr surface 38 of aperture 26, and clip 35 has a U-shaped hook 39 at the lower end thereof which is adapted to form a clasping or clamping engagement with the adjacent portion of the key stem which is immediately above aperture 26. Thus, whenever clip 35 is installed on the key stem in the manner illustrated in Figs. 2 and 3, the shank 40 thereof isflongitudinally disposed along one surface of key stem 23, and the resilient barb or prong 4| of clip 35 extends across the top surface 21 of the key stem and projects angularly downwardly therefrom to form a shearing engagement between resilient member 4| and button 20.

During the force fitting operation,'clip 35 is first installed on the upper portion of the key stem with the lower hooked end 39 in engagement with the top of aperture 26, and with the upper resilient member 4| projecting downwardly and outwardly from the top of the key stem as shown in Fig. 2. The control button 20 is then placed on top of the key stem, and thereafter the assembly is placed in a suitable press so that sufficientdownwardly directed pressure may be exerted on the upper surface 2| of the button to force top portion 22 of the key stem into the recess 30. As button 20 moves downwardly during the press-fitting operation, spring member 4| is first forced inwardly in opposition to the inherent resilient action which normally urges the element 4| into the extended position illustrated in Fig. 2. Thus, clip 35 causes a plastic deformation within button 20 without removing material therefrom or producing shear therein. After button 20 has been fully seated on the key stem, however, the continuous resilient act-ion exerted by the member 4| on the adjacent plastic material causes the plastic material within button 20 to flow underneath the member 4| and allow it to gradually resume the normal angularly downward position which is illustrated in Fig. 2. Thus, spring element 4| functions as a resilient barb or spike adapted to form an-efiicient and highly effective self-locking shear engagement between key stem 23 and the control button 20,

in the structural strength of the plastic button whichv normally occurs whenever such a, button is subjected to higher than normal operating temperatures for prolonged periods of time.

I claim:

1. In a keyboard key assembly, the combination which comprises a key stem having an aperture in the top portion thereof, a rodlike securing member extending between and anchored by the said aperture and the uppermost extremity of the said key stem with an integral prong extending outwardly and angularly downward therefrom, and a slightly elastic finger button pressure-fitted onto the said key stem thereby compressing the said prong to eifectively lock the said finger button in a predetermined position thereon as the said prong is resiliently urged outwardly so as to become imbedded within the slightly elastic material within the interior of the said button.

2. In a keyboard key assembly, the combination which comprises a key stem having an aperture in the top portion thereof, a slightly elastic control button in engagement with the said key stem and pressure-fitted thereon, and a rodlike securing memberhooked in the said aperture and having an integral resilient barb extending across and angularly downward from the top of the said key stem, the said barb becoming imbedded within the adjacent interior of the said button to establish an effective self-locking engagement therewith.

3. In a keyboard key assembly, the combination which comprises a key stem having an aperture in the top portion thereof, a relatively heavy plastic control button in engagement with the said key stem and pressure-fitted thereon, and a rodlike securing member interposed between the said button and the said key stem, the said member having a lower hook portion interlocked in said aperture and a resilient prong thereon extending across and angularly downward from the top of the said key stem and becoming resiliently imbedded within the adjacent interior of the said button to establish an effective shear resisting engagement therewith in such a manner that the securing action thereof is not substantially diminished by rapidly operating the keyboard while the latter is continually exposed to elevated operating temperatures.

4. In a keyboard key assembly, the combination which comprises a key stem having an aperture in the top portion thereof, a plastic controlbutton slidably engaged with the said key stem and pressure-fitted thereon, and a resilient wire clip interposed between the said button and the said key stem, the said clip having at one extremity a normally angularly outwardly extending compressible spring member engaged with said key stem and the other substantially U- shaped extremity hooked on the edge of the said aperture, the said compressible spring member being resiliently urged into the adjacent ductile interior of the said button so that the effectiveness of the bond between the said key stem and the said button will be substantially increased by forces tending to separate the said button from the key stem.

5. In a keyboard key assembly, the combination which comprises a key stem having an aperture in the body portion thereof, a slightly elastic control button having a recess therein for engaging the said key stem, and a wire clip with a hook at one extremity engaging an edge of the said aperture for restraining movement of the said clip with respect to the said key stem, the said wire clip having a resilient prong at its other extremity hooked over the end of the said key stem and resiliently urged angularly outward from the plane of the said key stem in such a manner as to effectively lock the said button in a predetermined position on the said key stem by becoming embedded within that portion of the ductile button which is immediately adjacent thereto.

CHESTER K. MARLOW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,052,616 Gardes Sept. 1, 1936 2,210,562 Anderson Aug. 6, 1940 2,304,036 Legarty Dec. 1, 1942

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