Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS3909564 A
Publication typeGrant
Publication dateSep 30, 1975
Filing dateAug 8, 1974
Priority dateAug 8, 1974
Publication numberUS 3909564 A, US 3909564A, US-A-3909564, US3909564 A, US3909564A
InventorsPurdy Harold Lawrence, Scheingold William Samuel, Youngfleish Frank Christian
Original AssigneeAmp Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Keyboard assembly with foldable printed circuit matrix switch array, and key actuator locking slide plate
US 3909564 A
This invention provides a keyboard assembly for installation in an electronic system of the type having discrete devices such as integrated circuit chips which are electrically actuated by the manual movement of keys. More particularly, the keyboard assembly consists totally of a cover, keys, cam plate, guide plate, contact plate, contacts deposited on flat flexible cable, a spacer, a base plate, and the bolts, etc. for mounting it.
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)


Palmyra; I-Iarold Lawrence Purdy, Hummelstown; Frank Christian Youngfleish, Harrisburg, all of Pa.

[73] Assignee: AMP Incorporated, Harrisburg, Pa.

[22] Filed: Aug. 8, 1974 [21] Appl. No.: 495,709

[52] US. Cl. 200/5 E; 200/5 A; 200/50 C;

200/159 B; 200/292; 200/325; 197/98; 317/101 F [51] Int. C13. HOIH 9/20; H01H 13/00; G06F 3/02 [581 Field of Search 200/1 R, 5, 16 A, 159 R, ZOO/159 A, 159 B, 275, 290, 50 C, 322328, 329-331, 340; 340/365 R, 365 A; 235/145 R; 179/90 K; 197/98; 317/101 F [56] References Cited UNlTED STATES PATENTS 2,969,439 l/196l Dubois 200/5 A X Primary E.\-aminer.lames R. Scott Attorney, Agent, or Firm-Allan B. Osborne, Esq.

[57] ABSTRACT This invention provides a keyboard assembly for installation in an electronic system of the type having discrete devices such as integrated circuit chips which are electrically actuated by the manual movement of keys. More particularly, the keyboard assembly consists totally of a cover, keys, cam plate, guide plate, contact plate, contacts deposited on flat flexible cable, a spacer, a base plate, and the bolts, etc. for mounting it.

1 Claim, 4 Drawing Figures U.S. Patant Sept 30,1975 Sheet 1 of 4 3,909,564

US. Patent Sept. 30,1975 Sheet 2 of4 3,909,564

US. Patent Sept. 30,1975 Sheet 3 Of4 3,909,564

US. Patent Sept. 30,1975 Sheet4 0f4 3,909,564

KEYBOARD ASSEMBLY WITH FOLDABLE PRINTED CIRCUIT MATRIX SWITCH ARRAY, AND KEY ACTUATOR LOCKING SLIDE PLATE BACKGROUND OF THE INVENTION Conventional keyboards such as found on Touch- Tone telephones contain 101 parts including mounting screws, studs and nuts. In addition to these many parts the final assembly requires the bringing together of three major subassemblies. Further, all the work in both subassembly and final assembly must be done by skilled workmen, with such work including countless soldering operations. Obviously the cost of the many parts plus skilled labor is high. Further, as is well known, humans make mistakes which lead to high failure rates of the assembled keyboards.

It is therefore an object of this invention to provide a keyboard assembly having only a few inexpensive parts. As a corollary yet distinct feature, it is an object to provide a keyboard assembly which is extremely simple to assemble and as such, is not subject to misassembly.

Another object of the present invention is to provide a keyboard assembly which is virtually foolproof insofar as operative manipulation is concerned.

It is yet another object of the present invention to provide a keyboard assembly which is exceedingly reliable in operation.

These and other objects, novel features and advan tages of the present invention will be readily apparent from the following detailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of the keyboard assembly constructed in accordance with the preferred embodiment of the present invention; and

FIG. 2 is a view showing the contacts and circuits deposited on a flat flexible cable used in the keyboard assembly of FIG. 1.

FIGS. 3 and 4 are side sectional views of a portion of the keyboard of FIG. 1 subsequent to its assembly and illustrating a key in an unactuated condition (FIG. 3) and actuated, condition (FIG. 4).

DESCRIPTION OF THE PREFERRED EMBODIMENT The several elements of the keyboard assembly have been exploded vertically to show the details of each element, the relationship of one element to another and also to illustrate the natural, uncomplicated method of assembling the elements to form the keyboard.

The lower most element in FIGS. 1, 3 and 4 is base plate on which the other elements rest. This plate is preferably made from steel with a chromate conversion coating.

Base plate 10 is made with a pair of downturned tabs 14 which provide means for fastening the keyboard assembly to a telephone or other keyboard-using device (not shown) by bolts 16 one of which is shown positioned in an aperture in the one tab visible in the drawing.

The subassembly positioned directly over the base plate consists of an end ofa strip of non-conductive flat flexible cable 18 folded back over itself. A spacer 20 is sandwiched inbetween.

Turning now to FIG. 2, the inside surface 22 of the cable 18 is displayed. This surface contains the circuitry for the keyboard. Reference numeral 24 points out the axis about which the cable is folded to provide the configuration seen in FIG. 1. The solid dots represent contacts 26 which are located on each side of the axis. The contacts are deposited on the cable via conventional methods in a symmetrical pattern such that when the cable is folded over, contacts on one side are in precise opposing registration with contacts on the other side. In some cases, one pair of opposing contacts constitute a switch while in other cases, two pair constitute one switch.

Conductors 30 connect contacts 26 to appropriate power sources, discrete devices, etc. (none of which are shown) which perform the necessary functions characteristic of the device to which the subject keyboard assembly is attached; e.g., a telephone. Circuits are closed by bringing one or more contacts on the one inside film surface into physical contact with one or more contacts on the opposite inside film surface.

The circles shown in FIG. 1 on cable 18 simply represent the location of some of the contacts 26 on the inside surface.

Although a number of non-conductive or insulative films are available from which flat flexible cable 18 can be made, a polyimide film sold under the trademark KAPTON by E. I. duPont de Nemours & Co. is preferred. The conductors generally consist of a deposition of a single layer of conductive material such as copper. The contacts preferably consist of a multilayered deposition having gold and other highly conductive metals therein. A preferred deposition consists of copper on the bottom, gold on top and nickel inbe tween.

Referring back to FIGS. 1, 3 and 4 and the subassembly, it was noted above that a spacer 20 is sandwiched between the folded portion of cable 18. This spacer is preferably made from polyester and contains a plurality of holes 28 FIGS. 3 and 4 which are in alignment with opposing contacts 26. These holes or openings allow a contact 26 to be pushed through the spacer 20 and into physical contact with an opposing contact. In the absence of a biasing force on a contact, the spacer electrically and physically isolates opposing contacts one from the other.

A switch plate 32, positioned over the cable-spacer subassembly, contains two kinds of members having spring characteristics; three commoning members 34 seen along one side of the plate and a plurality of switch members 36 spacedthroughout the surface of the plate. While only four switch,members are shown, it is to be understood that there are as many switch members as are keys; i.e., one switch member for each key.

The commoning members 34 consist of a strip of metal stampe out from the plate on three sides. The strip is bent upwardly into an L-shape to form arm 38 and elbow 39. The commoning members may be rotated over a short are with the point of rotation or hinge line being across the strip at its point of attachment to the plate. This hinge line is indicated generally by reference numeral 40.

The switch members 36 are also stamped out of the contact plate and formed into limbs 41 extending obliquely upwardly. Although each member is one piece, there are three functional parts. Two fingers 42 on each member are formed and bent obliquely downwardly. The free ends of each finger, curved up slightly to form a smooth surface, engages the outside insulative surface of the underlying flexible cable 18 with the point of contact immediately overlying a contact 26. In this manner, each switch member; i.e., the two fingers, contacts two contacts 26.

The fingers 42 are connected directly to the switch member proper 44 which moves about the hinge line located at the members point of attachment with the plate. This hinge line is indicated generally by reference numeral 46.

An overload spring 48 extends forwardly between the two fingers and moves about a hinge line located at its attachment with the spring member proper. This hinge line is indicated generally by reference numeral 50.

The edges of the switch plate 32 have been turned up to form vertical walls 52. These walls provide ridgity to the plate as well as providing a raised platform on which the overlying guide plate rests in the assembly.

The material preferably used in making switch plate 32 is either pre-tinned steel or stainless steel. As is now evident, the material must be resilient and capable of having spring characteristics such that when they are moved, they tend to return to their original position.

The overlying guide plate 54 has three long narrow slots 56 up through which the arms 38 of commoning switch members 34 project in the assembled keyboard. Interiorly, the guide plate has as many openings 58 as there are keys. These openings, being in alignment with the switch members below, receive the lower part of the keys so as to guide such in their vertical movements. A vertical stud 60, located at one end of the guide plate, is provided to guide and align the movement of the overlying cam plate.

Guide plate 54 is preferably made from glass-filled VALOX, a polyester sold under that tradename by General Electric Company.

Cam plate 62 rests on guide plate 54 and in like manner, has three long, narrow slots 64 through which arms 38 project. The plate further has a plurality of openings 66, these being in alignment with openings 58 and switch members 36. One wall of openings 66 is beveled to provide a camming surface as generally indicated by reference numeral 68.

A stud receiving slot 70 is located on one end of the cam plate.

As with guide plate 54, the preferred material used in making cam plate 62 is glass-filled VALOX.

Keys 62, although integral, have an upper and lower section with laterally projecting rims 74 dividing the two. One side wall of the lower section is provided with a beveled camming surface 76. The length of the lower section below the camming surface is such that when assembled, the bottom surface of the key is on the top of overload springs 48 on switch members 36. The length of the lower section in the direction parallel to slot 70 is less than the length of opening 66.

The top surface of the upper section provides an area for key designation symbols.

Preferably keys 72 are molded from acrylonitrilebutadiene-styrene resins (i.e., ABS).

The last element of the keyboard assembly is cover plate 78. The plurality of openings 80 thereon are sized to receive the upper section of keys 72. The under surface of each opening is recessed as generally indicated by reference numeral 82, to receive rim 74 on the keys. Vertical walls 84, surrounding each opening 80, provide support for keys 72. Cover plate 78 is preferably molded from ABS.

Each of the several elements in the keyboard assem-' bly have holes on two (cable 18) or four corners. These holes, along with suitable bolts (not shown), provide one means for securing the several elements together.

The assembly step of the keyboard illustrated in FIG. 1 simply requires stacking the several elements in the order shown and securing such together. FIG. 3 is a cross-sectional elevational view of an assembled keyboard. In addition to showing the assembly, FIG. 3 shows the keyboard in an unactuated condition.

As indicated above, the film or flexible cable 18 is folded back on itself to bring contacts 26 on one surface into a direct alignment with the contacts on the now opposing surface. Spacer 20, of an insulating material, provides the means for separating the two. Openings 28 in the spacer are also in direct alignment with the opposing contacts.

Attention is drawn to the position of switch member 36 and commoning member 34. Particularly of interest are the portions thereof which rest or bear on the upper outside surface of film 18. The members are preloaded or stressed upwardly so that the force bearing downwardly is negligible. With respect to commoning member 34, attention is also directed to the position of its arm 38 with respect to the wall defining opening 64 in cam plate 62. In this regard, attention is directed to the positioning of beveled surface 76 on key 72 and the wall defining opening 66.

Cam plate 62 is positioned on guide plate 54 so that stud 60 bears against the front end of slot 70.

As noted above, the bottom surface of each key 72 rests on top of a switch member 36.

FIG. 4 illustrates the actuated condition of the assembled keyboard.

ln depressing a key 72, cam plate 54 is moved forward by the camming action of the two abutting beveled surfaces 68-76. The forward movement pushes arm 38 of commoning members 34 forward and downward in an are so that the elbow 39 pushes down on cable 18. This pressure pushes one contact into electrical engagement with an opposing contact 26.

Concurrently, the key is pushing down on a switch member 36, the point of contact therewith being the overload spring 48. Initially the entire spring member arcs downwardly, the hinge point for the movement being at hinge line 46. The downward travel is transferred through fingers 42 to cable 18 and contacts 26 positioned below the fingers. The pressure pushes the contact through an opening in spacer 20 and into physical and electrical contact with an opposing contact on the other side thereby closing a circuit.

Additional downward pressure on key 72 is taken up by the overlaod spring 48 bending at hinge line 50. This prevents overflexing of cable 18.

When pressure is released from a key, the resiliency of the switch member restores it to its normal position and the reactive force exerted by arm 38 of commoning switch 34 returns cam plate 62 to its initial position.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as some modifications will be obvious to those skilled in the art.

What is claimed is:

l. A keyboard assembly comprising:

a. a flat flexible cable with a portion thereof folded back over on itself and having contacts deposited on both facing surfaces, contact on one surface being directly across from contacts on the other surface;

b. means for connecting the contacts into electrical circuits;

c. a layer of insulating material positioned between the two contact-carrying surfaces and having holes therethrough, said holes being in registration with opposing contacts;

d. a switch plate overlying the folded over cable and containing a plurality of resilient switch members comprising an elongated limb extending obliquely upwardly and a pair of fingers, one on either side of the limb, extending obliquely downwardly with the free end of each finger being adjacent an outside surface of the folded over cable and in direct alignment with a contact located on the inside surface, said plate further containing a plurality of commoning members comprising an L-shaped strip of material having a vertical arm and an elbow, said elbow being adjacent an outside surface of the folded over cable and in direct alignment with a contact located on the inside surface;

. a slidable cam plate positioned over and spaced a plurality of movable keys each having a bottom surface adjacent the free end of the limb on the switch member and a beveled surface on one side so that as one of the keys are depressed, the bottom surface thereof pushes downwardly on the limb whereby the two free ends on the fingers pushes the cable forcing the underlying aligned contacts into electrical engagement through a hole in the layer of insulating material, said beveled surface concurrently pushing on and laterally sliding the cam plate such that the arms of the commoning members extending through the slots are rotated about the point of attachment with the switch plate so that the elbows drive the underlying contacts into electrical engagement through the holes in the insulating layer.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2969439 *Oct 18, 1957Jan 24, 1961Svenska Relafabriken Abn AbElectric switching device
US3125895 *Jan 15, 1962Mar 24, 1964 Switch interlock and lockout unit
US3207862 *Jan 18, 1963Sep 21, 1965Standard Systems CorpPush-button selector switch with latch plate means
US3383487 *Jul 18, 1966May 14, 1968Wiener RobertThin flexible magnetic switch
US3472974 *Sep 25, 1967Oct 14, 1969Automatic Elect LabPushbutton switch activated by a slide with a plurality of toggle joints and cams
US3519766 *Feb 23, 1968Jul 7, 1970Rca CorpPushbutton mechanism
US3742157 *Apr 16, 1971Jun 26, 1973Lematex IncKeyboard switch assembly with improved movable contact
US3745288 *Aug 7, 1972Jul 10, 1973Gte Automatic Electric Lab IncFlexible printed wiring switch
US3800104 *Nov 13, 1972Mar 26, 1974Becton Dickinson CoLow profile keyboard switch assembly with snap action cantilever contact
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3982081 *May 20, 1975Sep 21, 1976Amp IncorporatedKeyboard assembly with overlapped flexible printed circuit cable switch
US3999025 *Jul 30, 1975Dec 21, 1976Burroughs CorporationLow profile tactile feedback keyboard switch assembly
US4028509 *Aug 29, 1975Jun 7, 1977Hughes Aircraft CompanySimplified tabulator keyboard assembly for use in watch/calculator having transparent foldable flexible printed circuit board with contacts and actuator indicia
US4051337 *Jan 27, 1976Sep 27, 1977Cavitron CorporationDental handpiece switch
US4063054 *Nov 14, 1975Dec 13, 1977Canon Kabushiki KaishaKey switch
US4066851 *Jul 1, 1976Jan 3, 1978Chomerics, Inc.Keyboard switch assembly having foldable printed circuit board, integral spacer and preformed depression-type alignment fold
US4099037 *Jun 21, 1976Jul 4, 1978National Semiconductor CorporationKey board switch assembly having canti-levered leaf spring contact assembly on common conductive frame
US4145584 *Apr 25, 1977Mar 20, 1979Otterlei Jon LFlexible keyboard switch with integral spacer protrusions
US4192976 *Dec 29, 1978Mar 11, 1980Gte Automatic Electric Laboratories IncorporatedPushbutton call transmitter
US4228330 *Jul 10, 1978Oct 14, 1980Litton Systems, Inc.Touch panel mechanism
US4297542 *Dec 19, 1979Oct 27, 1981Shumway Anthony GFolded circuit switch apparatus having multiple contacts
US4316066 *Nov 28, 1980Feb 16, 1982International Telephone And Telegraph CorporationKey switch with snap-action contact and resilient actuator
US4322588 *Apr 4, 1980Mar 30, 1982Umc Industries, Inc.Slide selector switch device
US4323740 *Feb 4, 1980Apr 6, 1982Rogers CorporationKeyboard actuator device and keyboard incorporating the device
US4324956 *May 15, 1980Apr 13, 1982Omron Tateisi Electronics Co.Fluid-proof slide switch
US4341934 *Nov 21, 1980Jul 27, 1982The Keyboard CompanyActuator for keyboard switches
US4342883 *Aug 22, 1979Aug 3, 1982Northern Telecom, Inc.Pushbutton switch assemblies for telephone sets
US4365536 *Oct 27, 1980Dec 28, 1982Whirlpool CorporationSliding actuator membrane switch for organ keyboard
US4370533 *Dec 5, 1980Jan 25, 1983Fujitsu LimitedKeyboard switch and process for production thereof
US4447681 *Feb 22, 1983May 8, 1984Amp IncorporatedSwitch key assembly having improved switch actuation
US4467150 *Feb 24, 1982Aug 21, 1984Digital Equipment CorporationElectronic keyboard
US4492838 *Feb 24, 1983Jan 8, 1985Amp IncorporatedKey switch having an actuator integral with the return spring
US4621373 *Mar 13, 1984Nov 4, 1986General Electric CompanyControl surface for a trunking personal radio
US4686499 *Mar 12, 1986Aug 11, 1987Cincinnati Microwave, Inc.Police radar warning receiver with cantilevered PC board structure
US4818828 *Jun 17, 1988Apr 4, 1989Smith Corona CorporationElectronic keyboard
US4874913 *Apr 22, 1988Oct 17, 1989Oki Electric Industry Co., Ltd.Luminous element holding structure for an illuminated key switch
US4877347 *Nov 25, 1987Oct 31, 1989Ta Triumph-Adler AktiengesellschaftKeyboard for typewriters or similar machines
US4942276 *Apr 11, 1989Jul 17, 1990Futaba Denshi Kogyo Kabushiki KaishaClicked key board switch
US4952762 *Apr 7, 1989Aug 28, 1990Futaba Denshi Kogyo Kabushiki KaishaKeyboard switch
US4972051 *Aug 7, 1989Nov 20, 1990General Electric CompanySwitch for two-way hand-held transceiver
US4977298 *Sep 8, 1989Dec 11, 1990Matsushita Electric Industrial Co., Ltd.Panel switch
US5075524 *Aug 30, 1990Dec 24, 1991Stocko Metallwarenfabriken Henkels Und Sohn Gmbh & Co.Electric pushbutton switch
US5121091 *Sep 27, 1990Jun 9, 1992Matsushita Electric Industrial Co., Ltd.Panel switch
US5152230 *Jun 20, 1983Oct 6, 1992Yaffa LicariJoining means for securing articles together
US5388922 *Jul 23, 1993Feb 14, 1995Smith Corona CorporationMiniature keyboard
US5422447 *Apr 14, 1994Jun 6, 1995Key Tronic CorporationKeyboard with full-travel, self-leveling keyswitches and return mechanism keyswitch
US5562203 *Sep 11, 1995Oct 8, 1996Brother Kogyo Kabushiki KaishaKeyswitch
US6781077Dec 14, 2000Aug 24, 2004Think Outside, Inc.Keyswitch and actuator structure
US6797906 *Mar 10, 2003Sep 28, 2004Brother Kogyo Kabushiki KaishaMembrane switch, key switch using membrane switch, keyboard having key switches, and personal computer having keyboard
US6911608May 23, 2003Jun 28, 2005Digit Wireless, LlcKeypads and key switches
US7005588 *Jun 10, 2004Feb 28, 2006Nokia CorporationKeyboard and a method for manufacturing it
US7126498Feb 26, 2003Oct 24, 2006Digit Wireless, LlcKeypad construction
US7391861May 22, 2001Jun 24, 2008Digit Wireless, LlcInput devices and their use
US7851718 *Mar 25, 2008Dec 14, 2010Panasonic CorporationElectronic equipment
US7911450 *Sep 14, 2005Mar 22, 2011Research In Motion LimitedInput apparatus for a handheld electronic device and method of enabling input employing the same
US7989716 *Nov 2, 2009Aug 2, 2011Foxconn Communication Technology Corp.Keypad assembly and electronic device using same
US8094806May 3, 2007Jan 10, 2012Nuance Communications, Inc.Input devices and their use
US8319734Feb 9, 2011Nov 27, 2012Research In Motion LimitedInput apparatus for a handheld electronic device and method of enabling input employing the same
US8362373 *Jul 2, 2012Jan 29, 2013Apple Inc.Keys with double-diving-board spring mechanisms
US8809703Dec 20, 2012Aug 19, 2014Apple Inc.Keys with double-diving-board spring mechanisms
US9704669 *Mar 30, 2016Jul 11, 2017Brother Kogyo Kabushiki KaishaKey input device for multifunction peripheral equipment
US20020025837 *May 22, 2001Feb 28, 2002Levy David H.Input devices and their use
US20030160712 *Feb 26, 2003Aug 28, 2003Digit Wireless, Llc, A Delaware CorporationKeypad construction
US20030173201 *Mar 10, 2003Sep 18, 2003Brother Kogyo Kabushiki KaishaMembrane switch, key switch using membrane switch, keyboard having key switches, and personal computer having keyboard
US20040031673 *May 23, 2003Feb 19, 2004Levy David H.Keypads and key switches
US20040256203 *Jun 10, 2004Dec 23, 2004Pekka PihlajaKeyboard and a method for manufacturing it
US20070057030 *Sep 14, 2005Mar 15, 2007Ladouceur Norman MInput apparatus for a handheld electronic device and method of enabling input employing the same
US20070256915 *May 3, 2007Nov 8, 2007Digit Wireless, Inc.Input Devices And Their Use
US20080237013 *Mar 25, 2008Oct 2, 2008Matsushita Electric Industrial Co., Ltd.Electronic equipment
US20100307904 *Nov 2, 2009Dec 9, 2010Foxconn Communication Technology Corp.Keypad assembly and electronic device using same
US20110128232 *Feb 9, 2011Jun 2, 2011Research In Motion LimitedInput apparatus for a handheld electronic device and method of enabling input employing the same
US20160293355 *Mar 30, 2016Oct 6, 2016Brother Kogyo Kabushiki KaishaKey Input Device, Method of Manufacturing the Same, and Image Recording Apparatus
USRE32419 *Jan 27, 1986May 12, 1987Engineering Research Applications, Inc.Molded keyboard and method of fabricating same
CN101909095BJun 5, 2009Aug 7, 2013深圳富泰宏精密工业有限公司Portable electronic device
CN103745857A *Dec 24, 2013Apr 23, 2014洪贵顺Keyboard lever and mechanical lever-type METAL DOME ultrathin keyboard
CN103745857B *Dec 24, 2013Mar 2, 2016深圳市汇创达科技股份有限公司键盘用杠杆及机械杠杆式metal dome键盘
DE3145130A1 *Nov 13, 1981Jun 16, 1982Keyboard CoKontaktbetaetigungsvorrichtung
EP0087369A1 *Feb 21, 1983Aug 31, 1983Digital Equipment CorporationImproved electronic keyboard
EP0099427A1 *Jul 9, 1982Feb 1, 1984Engineering Research Applications, Inc.Keyboard
EP0157035A2 *Aug 22, 1984Oct 9, 1985Cherry Electrical Products LimitedMechanical keyboard with membrane switch array
EP0157035A3 *Aug 22, 1984Mar 18, 1987Cherry Electrical Products LimitedMechanical keyboard with membrane switch arrray
EP1316980A1 *Feb 14, 2003Jun 4, 2003Phonak AgActuator or switch for miniature device
WO1980001219A1 *Nov 28, 1979Jun 12, 1980Serras Paulet EdouardPush button or keyboard with depressable keys
WO1987007759A1 *May 29, 1987Dec 17, 1987Bebiť + Co.Keyboard for use in difficult conditions
WO1995028727A1 *Apr 14, 1995Oct 26, 1995Key Tronic CorporationImproved keyboard with full-travel, self-leveling keyswitches and return mechanism keyswitch
U.S. Classification200/5.00E, 200/50.36, 200/517, 361/679.15, 200/292, 200/5.00A, 400/479, 200/325
International ClassificationH01H13/70, H01H13/705, H01H13/807, H04M1/23, H01H13/785
Cooperative ClassificationH01H2209/002, H01H13/807, H04M1/23, H01H13/705, H01H2223/024, H01H13/785, H01H2201/03, H01H2209/026, H01H2225/01, H01H2225/024, H01H2229/038, H01H2235/024
European ClassificationH01H13/807, H01H13/705, H01H13/785, H04M1/23