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US 4,489,227 AGranted
Back lighted, full travel push button membrane keyboard
AssigneeSheldahl, Inc.
InventorFredrick W. Lamarche
Life of this patent
Estimating the term…
Abstract
A keyboard having a side-lighted transparent support plane including a plurality of light-pipes vertically projecting therefrom through an overlying foam over-travel pad. A pair of patterned membrane switch layers, separated by a low density foam spacer, overly the over-travel pad and are positioned relative to a plurality of key-caps slidably mounted to the light-pipes. The sensation of key travel is achieved via the over-travel pad and/or a foam spring mounted beneath the key-caps with switch contact being made intermediate full key depression. An audible click is achieved via overlapping slidably abrasive projections.
Claims12
An electrical switch array comprising:
- (a) a support plane having a plurality of integrally formed projections extending from at least one surface thereof;
- (b) resilient support means overlying the surfaces of said support plane from which said projections extend and through which said projections pass;
- (c) membrane switch means overlying said resilient support means and having at least two flexible dielectric planar sheets, each separated from one another via an electrically insulative spacer, and wherein each of said dielectric sheets includes a plurality of patterned electrical contacts, said membrane switch means further including a plurality of apertures formed therethrough in the regions of said electrical contacts for mounting over said projections;
- and
- (d) key-cap means mounted over each of said projections and slidably operative relative thereto for depressibly bringing lower lying ones of the contacts on at least one of said flexible membrane sheets in the region of each depressed key-cap into electrical contact with the contacts on at least one other of said flexible sheets.
2 more elements
An electrical switch array comprising in combination:
- (a) a light transparent support plane having a plurality of integrally formed projections extending from at least one surface thereof;
- (b) a light source coupled to said support plane for transmitting light through the tops of said projections;
- (c) a resilient support pad overlying each of said surfaces from which said projections extend and through which said projections pass;
- (d) first and second flexible switch layers, each having a plurality of patterned electrically conductive switch contacts deposited thereon in the region of a plurality of apertures formed therethrough and corresponding to the location of said support plane projections;
- (e) a resilient support layer mounted between said first and second switch layers having a plurality of apertures formed therethrough relative to said support plane projections;
- and
- (f) a plurality of key-caps nonrotatively contained and slidably mounted to said support plane projections, whereby upon depressing each of said key-caps, said first and second switch layers may be brought into electrical contact in a region localized to said key-cap.
4 more elements
An electrical switch array comprising:
- (a) a light guiding support plane having a plurality of integrally formed projections extending from at least one surface thereof;
- (b) a light source mounted to said support plane such that said support plane guides the light to the top of each of said projections;
- (c) resilient support means overlying the surfaces of said support plane from which said projections extend and having a plurality of apertures through which ones of said projections pass;
- (d) membrane switch means overlying said resilient support means and having at least two flexible dielectric planar sheets, each separated from one another via an electrically insulative spacer and wherein each of said dielectric sheets includes a plurality of patterned electrical contacts, said membrane switch means further including a plurality of apertures formed therethrough in the regions of said electrical contacts for mounting over said projections;
- (e) key-cap means nonrotatively mounted over each of said projections and slidably operative relative thereto for depressibly bringing lower lying ones of the contacts on at least one of said flexible membrane sheets in the region of each depressed key-cap into electrical contact with the contacts on at least another one of said flexible sheets;
- (f) a foam spring mounted beneath each of said key-caps for resiliently supporting each of said key-caps away from said membrane switch means;
- and
- (g) means frictionally engaging each of said key-caps as it is depressed for audibly indicating the closure of said switch contacts.
5 more elements
Dependencies are inferred from the claim text.