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EXPANDABLE KEYBOARD FOR ELECTRONIC
POCKET CALCULATORS AND THE LIKE
FIELD OF THE INVENTION 5
This invention relates to electronic apparatus, and more particularly to expandable keyboards for the operation of such apparatus.
BACKGROUND OF THE INVENTION 10
It is evident from a glance at any pocket calculator that the minimum size of such apparatus is determined by the keyboard and by the display arrangements; not by the electronics within the device. Of the two determining factors, the keyboard occupies, by far, the 15 greater amount of surface space. With maximum surface dimensions of about three and one-half inches by seven inches, space available for a full spectrum of function keys is at a premium. Particularly when the human factors are considered and minimum key size is 20 determined, it is clear that fewer keys are employed than would otherwise be permitted by the electronics within the calculator. Space within the calculator goes unused instead.
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BRIEF DESCRIPTION OF THE INVENTION
The present invention is based on the realization that a folding or modular arrangement for a keyboard for a pocket electronic device would provide a much greater surface area for a keyboard than would otherwise be 30 possible. Yet, when the keyboard is folded, the device would still be pocket size. To this end, a keyboard of familiar layout for a full-size desk top data terminal is illustratively organized in three modular portions, each having surface dimensions equal to that available with 35 a pocket calculator. The portions hinge or snap fit in a side-by-side relationship with a main portion conveniently affixed to a housing for the electronics for the various functions. Electrical interconnection between the side portions of the modular or folding keyboard 40 arrangement is achieved at the edges of the portions by means of arrays of electrical interfaces exposed at the mating edges for interconnection.
BRIEF DESCRIPTION OF THE DRAWING 45
FIGS. 1 and 2 are side and top views of a keyboard arrangement in accordance with this invention;
FIG. 3 is a block diagram of apparatus including a keyboard arrangement in accordance with this invention; 50
FIGS. 4 and 5 are sectional views of portions of the keyboard arrangement of FIGS. 1 and 2;
FIGS. 6 and 7 are side views of the arrangement of FIGS. 1 and 2 illustrating hinge and latch arrangements for the various keyboard portions thereof; and 55
FIGS. 8 and 9 are side and cross-sectional views of alternative embodiments of this invention.
DETAILED DESCRIPTION
FIGS. 1 and 2 show side and top views of an illustra- 60 tive modular or foldable keyboard arrangement 10 in accordance with this invention. The keyboard arrangement includes three modular portions 11, 12, and 13 which interconnect electrically and hinge together mechanically. Each keyboard portion is nominally 3.25 65 inches by 3.25 inches, completely consistent in size and organization with any familiar pocket calculator. In fact, portion 13 considered alone as shown in the ab
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sence of portions 11 and 12 forms a familiar pocket calculator, portion 13 in FIG. 2 illustratively being affixed to a housing for both a display 16 and an electronic circuit. The electronic circuit is operative on display 16 for selective activation thereof in response to the selective depression of keys 17 of the keyboard portion 13 in conventional calculator fashion. Portion 13, then, with display 16 is illustratively operative as a familiar pocket calculator. The electronic circuit, therefore, is conventional and is well understood and commercially available.
FIG. 3 represents the electronic circuit as a block 20, portion 13 of the modular keyboard being represented as a block also designated 13. A conventional pocket calculator is thus represented in FIG. 3 by the blocks 13, 16, and 20. In accordance with an aspect of the present invention, circuit 20 includes additional electrical interconnection paths over and above those operative by the keys of portion 13. These additional paths are available for interconnections illustratively at the edge of portion 13 for mating with portions 11 and 12 of the keyboard arrangement of FIG. 2. The interconnection of portions 11 and 12 is represented in FIG. 3 by the addition of blocks 11 and 12 there. Circuit 20, in accordance with this embodiment of this invention, is operative in response to selective activation of the keys in portions 11 and 12 to apply different signals to display 16 than are applied by selective activation of the keys of portion 13. Circuit 20 thus can be seen to be available to provide a considerably greater number of functions (i.e., alpha-numeric) than a circuit for a pocket calculator would normally be called on to perform. Additional interconnection paths in this circuit over and above what is shown in the above-mentioned pocket calculator circuit are brought to the edge of portion 13 for interconnection.
One arrangement for interconnection is illustrated in FIGS. 4 and 5. FIG. 4 is a cross-section view of a part of portion 13 of the keyboard arrangement taken along line 2-2' of FIG. 2 along with a cross section of the mating portion of portion 12. In this illustrative embodiment, the top and bottom faces 30 and 31 of portion 12 form lips 32 and 33 for receiving a conductive elastomer side member 34. Portion 12 also houses a double-sided printed circuitboard 35 terminating to the right with metallic bumps 36. The bumps may be seen to be closely spaced with respect to elastomer side member 34.
Portion 13 is adapted to mate with portion 12 to make contact with metallic bumps 36. To this end, portion 13 includes top and bottom surfaces 40 and 41 which protrude beyond side wall 43 thereof in a manner to allow portion 12 to be inserted therebetween as indicated in FIG. 4. A printed circuit board 45 is secured to side wall 43 with metallic pins or eyelets 46 extending through both board 45 and side wall 43. Pins 46 extend beyond the side wall and thus are exposed or at least available for contact at the side wall, it is convenient for an insulating layer such as polyurethane layer, indicated by broken line 47 in FIG. 4, to cover side wall 43 to a thickness equal to the exposed length of the pins to provide a relatively smooth side wall appearance to the module portions.
In either case, when two portions of the keyboard arrangement are moved into an open or electrically interconnected position, bumps 36 and associated pins 46 compress localized regions of elastomer 34 to make contact therebetween as indicated most clearly in an
