US 3808389 A
A key for use in an electric contact keyboard for a mini-computer comprising a downwardly open shell whose top is the key face, the bottom periphery of the shell being fused with an integral resilient seal and return which is accordion-pleated in cross-section. A shank projects centrally from the underside of the shell and is provided adjacent its lower end with a neck which seats inside a corresponding aperture in the keyboard. The bottom of the shank is bifurcated and beveled to facilitate assembly. The shank also carries a contact member having a plurality of generally vertical legs terminating in generally horizontal feet which, when the key is depressed, wipe over contact points provided on the keyboard which carries a printed circuit.
Description (OCR text may contain errors)
United States Patent [1 1 Ramsay et al.
[111 3,808,389 1 Apr. 30, 1974 KEY FOR ELECTRIC CONTACT KEYBOARD  Inventors: Richard Ramsay, Babylon; Joseph P. Lanfear, Jackson Heights; Michael Bach, Long Island, all of NY.
 Assignee: Three Dimensional Circuits, lnc., Plainview, NJ.
 Filed: Jan. 26, 1973  Appl. No.: 326,625
 US. Cl. 200/159 B, 200/168 G  Int. Cl. H0lh 3/12  Field of Search 200/159 R, 159 B, 159 A,
200/166 PC, 166 BC, 168 G, 5 A; 340/365  References Cited UNITED STATES PATENTS 3,641,286 2/1972 Berezowski 200/159 R X 3,506,795 4/1970 Schmidt 3,048,673 8/1962 Kirk 200/159 B X FOREIGN PATENTS OR APPLICATIONS Great Britain ZOO/159 B Primary ExaminerRobert K. Schaefer Assistant Examiner-William J. Smith Attorney, Agent, or Firm-Burgess, Dinklage & Sprung ABSTRACT A key for use in an electric contact keyboard for a mini-computer comprising a downwardly open shell whose top is the key face, the bottom periphery of the shell being fused with an integral resilient seal and return which is accordion-pleated in cross-section. A
shank projects centrally from the underside of the shell and is provided adjacent its lower end with a I neck whichseats inside a corresponding aperture in the keyboardf'l'he bottom of the shank is bifurcated and beveled to facilitate assembly. The shank also carries a contact member having a plurality of generally vertical legs terminating in generally horizontal feet which, when the key is depressed, wipe over contact points provided on the keyboard which carries a printed circuit.
3 Claims, 3 Drawing Figures KEY FOR ELECTRIC CONTACT KEYBOARD The present invention relates to a novel key for use in an electric contact keyboard such as a calculator or computer.
Small calculators generally comprise a housing provided with openings through which keys project. With the housing removed there is exposed the underlying structure which is the keyboard assembly. The keyboard may be made of plastic, fiberboard or the like and has printed thereon electric circuitry terminating in various contact points adjacent to the individual key assemblies. The individual key assemblies are attached by various means to this keyboard assembly. The keys are secured to the keyboard in a fashion which permits limited displacement of the keys relative to the plane of the board so that metallic members carried by the keys can make contact with the contact members and complete circuits as required. Means, such as leaf and compression springs, are usually required to urge the keys into non-contact position.
The foregoing structures take considerable space which is not always available with miniaturized machines, so frequently certain safeguards are omitted such as devices to shield the keyboard contact points from contaminants which would interfere with completion of a circuit. Othertimes the manner of assembly does not permit simple servicing or replacement of individual keys rather than the whole keyboard. Oftentimes, construction and assembly of the keys are complicated.
It is accordingly an object of the present invention to provide keys which can be manufactured and assembled inexpensively, joined easily to keyboards in a manner which permits easy repair and replacement, which make sure contact with the contact points on the key board and which are protected from malfunction du to contaminants and residues.
These objects and advantages are realized in accordance with the present invention pursuant to which there is provided a key for use in an electric contact keyboard comprising a downwardly open shell whose top constitutes the key face, a shank integral with said shell and projecting downwardly from said shell, the lower end of said shank being bifurcated and being provided with a neck, an annular contact member having a body portion surrounding said shank and a lower contact portion, and a resilient seal conforming to the periphery of the opening of said shell, whereby said key can be inserted into an aperture in a circuit member by flexing the bifurcation of said shank until said circuit member aperture is positioned about said shank neck with said seal being compressed between said shell and said circuit member thereby to maintain said key in raised non-contacting position, depressing of said key against the urging of said seal effecting contact between said contact member and said circuit member.
In accordance with a preferred aspect of the invention the resilient seal in cross-section is accordion pleated and is integral with the shell of the key. Desirably the lowennost end of the shank of the key is beveled so as to facilitate its insertion through the aperture in the circuit member. By flexing the bifurcations of the shank and displacing them toward one another the key can be removed from its aperture.
The lower contact portion of each contact member may comprise a plurality of leg members each including a generally downwardly projecting leg ending in a generally horizontally projecting foot, depressing of said key causing said foot initially to make contact with said circuit member and then to slide over said circuit member wiping of? contaminants to ensure secure contact. v
The key shell and shank are preferably formed of relatively stiff plastic, such as acrylonitrile-butadienestyrene rubber, polystyrene, polypropylene, or the like. Preferably they are formed by injection molding. The resilient seal can be a separate soft rubbery material separately molded but preferably it is integral with the shell either being molded simultaneously therewith or, preferably, being formed by taking a pre-formed shell with shank attached, arranging the shell in a mold and supplying plastic of suitable'character to fuse with the shell and form the integral seal.
The neck of the shank in cross-section will of course conform to the aperture in the keyboard and may be round. Advantageously it will be out of round and asymmetrical, e.g. D-shaped, which will ensure the proper orientation of the key to the board since the face of the Key will bear some letter, number of other indicia. Orientation can also be established by the shaping of the key shell and the corresponding opening in the housing.
The contact member can be fabricated of metal or it can be stamped out of sheet metal and then bent by suitable means. A suitable base material is a beryllium copper alloy of spring temper.
The invention will be further described with reference to the accompanying drawing, wherein:
FIG. 1 is a vertical section through a key in accordance with the invention and a portion of the keyboard and housing with which it cooperates;
FIG. 2 is a top plan view of the contact member of FIG. 1, and
FIG. 3 is a lateral elevation of the contact member of FIG. 2. v
Referring now more particularly to the drawing, in FIG. 1 there is shown a portion of a mini-calculator comprising a housing 10 provided with openings 12, only one of which is here shown. Beneath the housing 10 is a keyboard 14 carrying printed electric circuitry (not shown) terminating at various contact points 16 a, b, etc., adjacent an aperture 18 in the keyboard, the aperture 18 being aligned with an opening 12. A key 20 is provided for each aperture.
The key 20 comprises a face 22 which can bear a letter, numeral or other indicia (not shown) surrounded by an integral shell or skirt 24 projecting downwardly therefrom. Also integral with shell 24 about its bottom is an accordion pleatedresilient member 26 which rests on the top of keyboard 14 so as to form a seal therewith; the resilient seal 26 in assembled condition is flexed so as to exert an upward force on the key so that the seal is maintained whether the key is inactive or depressed.
Also projecting downwardly from the face-of the key centrally thereof is a shank 28. The upper portion of the shank is larger in cross-section than the aperture 18 and the lowermost portion of the shank is also larger in cross-section, but in between the shank is smaller in cross-section so as to form a neck 30 which sits inside aperture 18, the key being capable of upward and downward movement within the aperture to the extent established by the length of neck 30.
The lower end of the shank is provided with a cut-out 32 so that the shank end isbifurcated; the ends can be flexed toward one another because of the cut-out 32. Advantageously the lower end of the shank is beveled as at 34. Thus, the key can be joined to the keyboard from above by pressing the shank 28 intothe keyboard aperture 18, the bevel 34 contacting the aperture. Downward pressure causes the bifurcated portions of the shank to be deflected towards one another until'the bevel advances fully through the aperture 18 at which point the aperture 18 surrounds the neck 30, as shown. The key cannot be withdrawn readily from the aperture because there is no corresponding bevel around the neck 30. To remove the key in servicing, the lower ends of the bifurcation must be compressed toward one another by a tool until their temporary cross-section is smaller than the aperture 18, whereby the key can then be pulled upwardly.
Around the shank 28 is a metallic contact member 36 either force fit onto the shank or molded thereabout. As shown in FIGS. 2 and 3, the member 36 comprises a shank-encircling body 38 and, in this case, four contact portions 40. Each portion 40 comprises a leg 42 extending generally downwardly and ending in a foot 44 extending generally horizontally.
The resilient urging of seal 26 keeps feet 44 some distance above contact points 16 a, b, etc., although the feet and points are in alignment by the proper orientation of key and keyboard and/or housing. When the key is depressed against the urging of seal 26 the feet 44 first contact receptive points 16 and then deflect horizontally, wiping over the points to ensure secure contact therewith by virtue of the configuration of the legs and feet. Contact of two feet 44 with two points closes a circuit, in known manner.
The key itself may be round, square, elliptical or the i like, as may be the shank although the shank is prefera- The novel keys' havea minimum number of parts and can be assembled and disassembled simply, functioning reliably for long periods of time. The key face may have indicia molded therein or they may laterbe applied as by adhesive, in known manner.
It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.
What is claimed is:
1. A key for use in an electric contact keyboard comprising a downwardly open stiff plastic shell whose top constitutes the key face, a shank integral with said shell and projecting downwardly from said shell beyond said shell, the lower end of said shank being bifurcated and beveled and'being provided with a neck, an annular contact member having a body snugly surrounding said shank and a plurality of leg members each integral with said body and including a generally downwardly projecting leg ending in a generally horizontally projecting foot, and a resilient seal integral with said shell about its opening and accordion pleated in cross-section, whereby said key can be inserted into an aperture in a circuit member by flexing the bifurcation of said shank until said circuit member aperture is positioned about said shank neck with said seal being compressed between said shell and said circuit member thereby to maintain said key in raised non-contacting position, depressing of said key against the urging of said seal causing said feet of said contact member initially to make contact with said circuit member and then to slide over said circuit member to ensure secure contact.
2. In combination, a key as defined in claim 1 and a keyboard carrying a printed circuit constituting the circuit member, said keyboard being provided with an aperture through which said key shank extends.
3. in combination, a plurality of keys as defined in claim 1 and a keyboard carrying a printed circuit and a plurality of contact points constituting the circuit member in alignment with said contact points of said keyboard.