Electricity: circuit makers and breakers – Multiple circuit control – Multiple switch
Reexamination Certificate
1999-06-23
2001-08-14
Friedhofer, Michael A. (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Multiple switch
C200S517000
Reexamination Certificate
active
06274825
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the design and structure of an assembly for a keypad having particular, but not exclusive, application to the field of mobile phones.
Market forces require that mobile phone manufacturers produce an ever-increasing variety of mobile phones. In order to benefit from economies of scale and to minimize design effort for a particular model of mobile phone, it is advantageous to make use of components, wherever possible, which are common to a range of models.
SUMMARY OF THE INVENTION
One aspect, the present invention provides a method of constructing assemblies for keypads with different key layouts using substrates each having the same pattern of electrical-contact regions formed thereon and domed contact elements. The method includes the steps of selecting a first design of key layout; providing a first insulating layer having a plurality of apertures dependent on the first design; and mounting the contact elements to confront corresponding electrical-contact regions of a first of said substrates with the first insulating layer disposed therebetween. Each of the apertures being registered with a contact element, thereby to produce an assembly having the first design key layout. The method further includes the steps of; selecting a second design of key layout, the second design being different to the first key layout; providing a second insulating layer having a plurality of apertures dependent on the second design; and mounting the contact elements to confront corresponding electrical-contact regions of a second of the substrates with the second insulating layer disposed therebetween, each of said apertures being register with a contact element, thereby to produce an assembly having the second design key layout.
This design methodology allows a substrate having a standard pattern of electrical contact regions to be used for a range of keypad designs having different key spacings. For each design, a customised insulating layer is used.
In another aspect, the present invention provides an assembly for a keypad, which includes: a substrate having a plurality of electrical-contact regions, each region being defined by a first electrical terminal and a second electrical terminal; an array of domed contact elements, the elements being mounted to confront a corresponding electrical-contact region and overlie only a portion thereof; an insulating layer disposed between the substrate and the contact elements and including a plurality of apertures, each aperture corresponding to an electrical-contact region, each element being depressible from a first natural bias position to a second distorted position in which a summit portion of the element passes through its corresponding aperture to contact its corresponding electrical-contact region, thereby to establish electrical connection between the first and second terminals of the corresponding electrical-contact region.
This structure of assembly for a keypad allows a substrate having a particular pattern of electrical-contact regions to be used for a range of keypad designs having different key spacings. It will be appreciated that this is achieved because, in one design, each contact element overlies a portion of the corresponding electrical-contact regions, whereas, in another design, each contact element can overlie a different portion of the corresponding electrical-contact region—thereby to provide for different key spacings.
Preferably, the area enclosed by the electricai-contact region is greater (preferably substantially greater) than the footprint area of the dome of the corresponding contact element. Advantageously, the former area is between 1.5 and 3 times the latter area. Preferably, the former area is approximately twice the latter area. The greater the area of the electrical-contact region relative to the footprint of the dome of the corresponding contact element, the more flexibility there is in locating the corresponding contact element.
In accordance with the invention, the eletrical connection between the first and second terminals can be achieved through ‘edge connection’ or ‘centre connection’. in edge connection, when electrical contact between the first and second terminals is achieved, a section of the rim of a contact element and its summit portion contact the first and second terminals, respectively. In centre connection, the summit portion alone of a contact element provides contacts closely-spaced first and second terminals.
In accordance with the invention, examples of edge connection and centre connection can be included in a single keypad assembly design.
In a still further aspect the present invention provides an assembly for a keypad including an array of domed contact elements, a substrate having a plurality of electrical-contact regions, the contact elements being mounted so as to confront a corresponding electrical-contact region, each contact element being depressible so as to snap from a natural-bias position in which it does not contact the corresponding electrical-contact region to a distorted position in which a summit portion of the contact element contacts the corresponding electrical-contact region, wherein each contact element overlies only a portion of the corresponding electrical-contact region.
Exemplary embodiments of the invention are hereinafter described with reference to the accompanying drawings, in which:
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Aaltonen A.
Ala-Lehtimäki T.
Mehtonen J.
Antonelli Terry Stout & Kraus LLP
Friedhofer Michael A.
Nokia Mobile Phones Limited
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