United States Patent [191
`Ipcinski et al.
`
`[11]
`[45]
`
`Patent Number:
`Date of Patent:
`
`4,818,827
`Apr. 4, 1989
`
`[54] LOW FORCE MEMBRANE SWI'TCH
`[75] Inventors: Ralph G. Ipcinski, Hollis, N.H.;
`Douglas M. Odom, Phoenix, Ariz.
`[73] Assignee: AMP Incorporated, Harrisburg, Pa.
`[21] Appl. No.: 178,666
`[22] Filed:
`Apr. 7, 1988
`[51] Int. Cl.‘ .................. .. H01H 13/70; H01H 11/00;
`B05D 5/12
`[52] U.S. C1. ................................... .. 200/5 A; 29/622;
`178/18; 200/512; 427/58; 427/96
`[58] Field of Search ............... .. 200/5 A, 159 B, 86 R,
`200/292, 308, 317; 29/622; 178/18; 427/58, 96
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`2,843,695 7/1958 Osuch et al. .................... .. 200/86 R
`3,996,430 12/1976 Eberwein et a1.
`200/5 A
`4,143,253 3/1979 Wagner et al.
`200/5 A
`4,217,473 8/1980 Parkinson ........ ..
`200/ 5 AX
`4,287,394 9/1981 Hargita et al.
`ZOO/5 A
`
`4,360,716 ll/ 1982 Fiorella . . . . . . . . .
`
`. . . . . . . .. 200/5 A
`
`. . . .. 200/5 A X
`4,391,845 7/1983 Denley . . . . . . . . . .
`.......... .. 178/18
`4,564,079 l/1986 Moore et al. .
`4,587,378 5/1986 Moore ......................... .. 178/18
`4,694,126 9/1987 Aiken, Jr. et al. . . . .
`. . . .. 200/5 A
`4,701,579 10/1987 Kurachi et al. .................. .. 200/ 5 A
`Primary Examiner-J. R. Scott
`Attorney, Agent, or Firm-Katherine A. Nelson
`[57]
`ABSTRACT
`The invention is directed to a membrane switch com
`
`prising a ?rst layer 30 of flexible insulating material and
`a second layer 50 having relatively inflexible character
`istics, each layer 30, 50 having an array of conductors
`40, 54 disposed thereon and de?ning a plurality of
`switch point areas over a substantial portion of the
`respective layers. The ?rst sheet is transparent and
`carries visible’ symbols on the inner surface thereof
`formed by a ?rst layer 36 of inks printed thereon and
`further includes a barrier coating over such symbols to
`provide contrast therefore. The ?rst array 40 of con
`ductors is printed on the barrier coating. The second
`array 54 of conductors is printed on the inflexible layer.
`The ?rst and second arrays 40, 54 of conductors are
`connected to respective voltage sources, preferably by
`further arrays of conductors 42, 56 disposed over at
`least portions of the ?rst and second arrays, 40, 54 the
`further arrays 42, 56 being of a material having a higher
`conductivity than the material used for the ?rst and
`second arrays 40, 54. Spacer means 58 for the switch is
`formed by printing an array of spaced apart dots of a
`dielectric and insulating coating on top of at least one of
`the arrays of conductors in the de?ned switch point
`areas to hold the switch point areas normally apart until
`pressure is placed thereupon to deform the ?rst sheet 30
`and effect a switch closure between corresponding
`switch point areas of the arrays 40, 54. A method for
`making the switch is also disclosed.
`
`12 Claims, 6 Drawing Sheets
`
`1
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`Apple Inc., et al.
`Exhibit 1012
`Apple Inc., et al. v. Global Touch Solutions, Inc.
`IPR2015-01175
`
`Exhibit 1012, Page 001
`
`

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`US. Patent Apr. 4, 1989
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`Sheet 1 0f 6
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`4,818,827
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`Exhibit 1012, Page 002
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`

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`U.S. Patent
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`Apr. 4, 1989
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`I!4
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`818,827
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`
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`

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`US. Patent Apr. 4, 1989
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`Sheet 3 0f 6
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`4,818,827
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`Exhibit 1012, Page 004
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`

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`US. Patent
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`Apr. 4, 1989
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`Sheet 4 of 6
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`4,818,827
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`Exhibit 1012, Page 005
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`

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`US. Patent Apr. 4, 1989
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`Sheet 5 of 6
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`4,818,827
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`56c
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`$56
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`
`Exhibit 1012, Page 006
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`

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`US. Patent Apr. 4, 1989
`
`Sheet 6 0f 6
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`4,818,827
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`Exhibit 1012, Page 007
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`

`
`FIELD OF INVENTION
`This invention relates to membrane switches and
`particularly to membrane switches requiring a sensitive,
`or low force, actuation for use in conjunction with
`instructive overlays.
`BACKGROUND OF INVENTION
`Membrane switches are widely used as a special type
`of keyboard for calculators, computers, input devices
`for manipulating equipment and machinery, and for
`educational purposes. In US. Pat. No. 4,360,716
`granted Nov. 23, 1982, such a switch is shown in con
`junction with a learning aid wherein a template having
`symbols thereon is laid over the switch so that an opera
`tor, when touching such symbols, will activate such
`switch. This patent includes a teaching of providing
`conductive traces on the inner surfaces of plastic sheets
`held apart by screened or coated insulating dots or
`points on spaced centers; the combination providing
`what is called a broad area actuated switch. This means
`that relatively broad areas of switch action are de?ned
`by the conductive traces rather than speci?c points.
`In US. Pat. No. 4,391,845 issued July 5, 1983, there is
`a membrane switch disclosed which is a point-type
`switch, meaning that the switch contains a number of
`discrete switch points, each of which is typically associ
`ated with a symbol such as one through ten or zero or
`a letter, or some other such instructive symbol. The
`4,391,845 patent teaches the use of spacer areas which
`are separated from the contact paths, or traces of the
`switch, and which, in this patent, may be made of insu
`lating materials screened or coated to be isolated from
`conductive traces. These isolated traces are taught as
`being built up of layers which may be either conductive
`ink as a ?rst layer or have additional layers of noncon
`ductive ink and/ or an adhesive material.
`These patents form a background for the present
`invention which has as its object the provision of a
`membrane switch having only two plastic layers and
`screen printed conductive traces with screen printed
`insulating spacers in conjunction with a coating carry
`ing symbols and instructions arranged to be suf?ciently
`thin and responsive to touch as to be actuated through
`multiple pages laid over the top of the switch in the
`manner of a book. It is a further object of the invention
`to provide a low-cost and sensitive membrane switch
`for use in conjunction with instructive aids which mini
`mizes the use of insulating sheets of which the switch
`contains only two, and therefore the associated labor
`required by the object of the invention to provide a
`membrane switch which can be fabricated by a variety
`of processing steps, including printing, screening, li~
`thography for both appearance and symbol purposes,
`and for conductive and insulating traces and moreover,
`wherein the various coatings are protected against
`wear, moisture and damage by being within the enve
`lope of the membrane switch.'
`
`40
`
`45
`
`SUMMARY OF THE INVENTION
`This invention relates to a method and apparatus. The
`method here taught embraces the steps of printing,
`screening, or coating a thin, ?exible membrane sheet of 65
`plastic material in a variety of steps and colors forming
`indicia in terms of symbols, instructions, and with deco
`rative appearance and thereafter over the top of such
`
`1
`
`LOW FORCE MEMBRANE SWITCH
`
`4,818,827
`2
`coating, screening or printing layers of conductive,
`insulating, and adhesive materials to form an area
`switch network. The method provides the basis of a
`membrane switch which is thinner than heretofore used
`wherein such instructive coatings were typically on the
`opposite side of the switch coatings, or outside of the
`switch envelope and required a protective ?lm layer
`thus rendering a laminated construction less ?exible
`than desired. The apparatus of the invention embraces a
`membrane switch of the area variety which contains
`only two layers of plastic sheet material with the rest of
`the switch including symbols and instructions, conduc
`tive traces and insulation spacers and adhesives being
`achieved through multi-pass printing or screening to
`de?ne extremely thin coatings allowing for optimum
`sensitivity. This sensitivity to the touch of an operator
`allows use of the switch with the so-called “talking
`book” applications wherein books of up to 12 or more
`pages of thin paper or plastic may be laid over the mem
`brane switch and the switch activated by pressing
`through the sheets of the book. Other switch functions
`are provided in addition to the area switches for respon
`sive instructions, such as yes, no, on, off inputs.
`
`IN THE DRAWINGS
`FIG. 1 is a scaled down perspective of the switch of
`the invention shown in conjunction with one preferred
`use, the various elements exploded for clarity;
`FIG. 2 is a schematic, exploded cross-sectional view
`of the various layers and coatings comprising the switch
`of the invention shown much enlarged from actual size;
`FIG. 3 is a view of the switch component shown in
`FIG. 2, but assembled as in actual use with the ?nger of
`an operator effecting switch closure;
`FIGS. 4, 5, and 6 are plan views of a portion of the
`membrane part of the switch, showing respectively
`three of the coatings employed;
`FIG. 7 is a plan view of the membrane side of the
`switch showing several representative coatings, and in
`addition, conductive traces leading to a connector input
`and output area;
`FIGS. 8, 9, 10, and 11 are plan views showing por
`tions of the bottom, or ?xed, part of the switch, showing
`various coatings employed to effect switch structure.
`FIG. 12 is a plan view showing the assembly of coat
`ings of FIGS. 8 through 11 in representation.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`Referring now to FIG. 1, there is shown a preferred
`embodiment of the invention in the form of a teaching
`aid, here stylized for use with pre-school learning lev
`els, it being understood that the invention concepts
`have uses in a wide variety of applications wherein the
`same needs for sensitivity, and therefore thinness, of
`switch laminated structure obtain. As shown in FIG. 1,
`there is a “book” 12 made up of leaves, or sheets, 14
`which typically are of thin paper or thin plastic having
`printed thereon symbols 15 forming indicia. The book
`12 is designed to ?t into a plastic frame 16, which itself
`?ts over the top layer 30, which is the membrane part of
`the switch of the invention. The layer 30 in turn ?ts
`over and is laminated to the lower layer of the switch,
`such layer shown as 50, which itself is bonded to the flat
`top surface of a frame 70. In use, the layers 30 and 50 are
`bonded together and bonded to frame 70 with the frame
`16 attached to frame 70 permanently. Electronic cir
`
`Exhibit 1012, Page 008
`
`

`
`0
`
`4,818,827
`4
`3
`ity, thinness, and insulating quality characterize the
`cuits may be contained beneath the upper surface of
`need for the printing forming the layer 36.
`frame 70 including, for example, a speaker for audio
`Next, in accordance with the method of the inven
`output and various logic and memory circuits to facili
`tion, a layer shown as 40 in FIGS. 2 and 4 is screen
`tate the intended use of the device. The frame 16 in
`printed on top of the layer 36 to form the bulk of the
`cludes separate apertures 20 which line up with switch
`conductive array on the membrane part 30 of the
`areas 21, 22 on respective layers 30, 50, which form the
`switch. The pattern that is illustrated in FIG. 4 includes
`membrane switch.
`a series of bars 400 and a series of dots 40b intercon
`Each of the layers 30 and 50 includes tails shown as
`nected to each other by small carbon or graphite traces
`48 and 64 which carry conductive traces to the conduc
`40d. Carbon and graphite inks readily commercially
`tive areas of the two layers respectively. As can be
`available, of the so-called solvated type are preferred,
`discerned in FIG. 1, the membrane switch layer 30
`and when utilized with standard silk-screening tech
`includes two broad areas Al and A2 of switch location,
`niques, one pass will provide a thickness of on the order
`such areas coinciding with the areas of symbols on the
`of 0.0004 to 0.0006 inches in thickness, found adequate
`leaves 14 of book 12.
`for the present use which calls for a carbon trace on the
`In use, the device 10 may be manipulated through
`order of 0.050 inches in width and which, as will be
`instructions given aurally, and the manipulation of
`described hereinafter, is made in conjunction with the
`switches 21 which, in the embodiment shown, include
`more conductive traces of a silver composition ink. The
`four switch structures, in conjunction with the touching
`dots 40b are on the order of 0.050 inches in width and by
`of the various symbols in book 12 which serve to close
`0.050 inches in length; the same thickness being em
`switches under such symbols through the membrane
`ployed as they are laid down in the same pass as the legs
`layer 30 and its associated layer 50.
`40a. Also shown in FIG. 4 are the separate switch
`Turning now to FIG. 2, a much enlarged and sec
`points 21, including a carbon bar structure 400 and addi
`tioned schematic reveals the layers 30 and 50 with the
`tional dots 40b.
`various coatings to be applied thereto shown separated.
`The next step in accordance with the method of the
`Layer 30 which is indeed the membrane or ?exible part
`invention is the printing as by screening of a conductive
`of the switch includes a sheet 32 of plastic insulating
`ink containing metal particles such as silver which is
`material which may be fabricated from a wide variety
`more conductive than that of the carbon traces of the
`of sheet materials which are insulating and have good
`layer 40. The more conductive layer is shown as 42 in
`dielectric properties, are essentially transparent and
`FIGS. 2 and 5. As can be discerned in the latter Figure,
`clear, and adequately ?exible to serve the switch func
`the layer 42 includes a series of dots 42b screened on top
`tion. The material Lexan, a polycarbonate manufac
`of the dots 40b of the carbon layer 40. Additionally, are
`tured by the General Electric Company was used in an
`provided conductive traces 42a and 420, which extend
`actual embodiment, the material chosen being on the
`from the switch points 21 along the length membrane
`order of b 0.005 inches in thickness and of the so-called
`switch layer 32, being directly bonded to the surface of
`“velvet” type, having one side textured, the other side
`32 to provide low resistance paths to such switch points.
`being smooth or slick and coated or printed upon to
`The conductive traces 42c which are laid down over
`de?ne half of the switch of the present invention. Such
`portions of the carbon layer reduce the overall resis
`texturing is shown as 34 in FIG. 2. In accordance with
`tance of the path from the switch points formed by such
`the method of the invention, rolls or sheets of material
`layer to the sources of voltage for switches as con
`32 are fed through appropriate printing or screening
`nected through the tails 48 and 64 heretofore men
`equipments in a series of passes laying down a series of
`tioned.
`layers. In accordance with the invention, the ?rst layer
`In an actual embodiment, the more conductive mate
`to be laid down is 36, and this layer is comprised of a
`rial was a DuPont silver ink known as 5007 which
`series of printings or screenings shown as 38 to form the
`through normal silk-screening practice, provides a
`symbology and color of the switch to be seen through
`thickness on the order of 0.0005 inches and a conductiv
`the top of the switch, and at the same time, protected by
`ity many times that of carbon. As can be appreciated,
`the sheet 32 against wear through use or damage by
`the use of the silver ink in the manner disclosed opti
`accident. In an actual embodiment, the colors laid down
`mizes the factors of low resistance and low cost, the
`in order included yellow, blue, a light purple, and a dark
`bulk of the printed area being comprised of carbon. The
`purple, with a ?nal screen barrier of off-white; the total
`width of the silver trace employed in this thickness is on
`thickness of such screenings being on the order of
`the order of 0.025 inches.
`0.00125 inches in thickness. Protection of instruction
`Next, in accordance with the method of the inven
`symbology and indeed of the switch structure itself is
`tion, a layer of adhesive shown as 46 in FIG. 2 and in
`most particularly required in the switch points 21 which
`FIG. 6 is applied directly to the interior surface of layer
`are directly engaged repeatedly in the use of device 10.
`32. As can be seen in FIG. 6, the switch activation areas
`Since the bulk of the actuation of the remaining areas is
`21 are left free of adhesive. Certain of the traces 420 are,
`through leaves 14 of book 12, wear of the symbols is less
`however, covered over by the adhesive and, while not
`relevant in this particular embodiment, but it is to be
`shown altogether, it is to be understood that the free
`understood that the invention in this aspect embraces
`areas around the periphery of the switch, including the
`other applications where such wear is more critical.
`spine area 51 as shown in FIG. 1, are employed to ac
`The layer or coating 36, including the various steps of
`commodate the adhesive to get an effective laminated
`printing, may be achieved through standard silk-screen
`structure and sealing.
`ing techniques, or even indeed, through lithographic
`In FIG. 2, the lower or fixed portion of the mem
`multi-pass printing. A wide variety of colored and
`brane switch of the invention is shown including a plas
`tic sheet 50 which, in the preferred embodiment, was
`white inks of either the solvent or nonsolvent, ultravio
`constituted by- a polyester film material such as Mylar
`let curable types are available and known to those in the
`printing arts. Characteristics of stability, some ?exibil
`from the DuPont Company, EL or D grade, on the
`
`40
`
`Exhibit 1012, Page 009
`
`

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`4,818,827
`
`O
`
`5
`
`35
`
`50
`
`65
`
`25
`
`5
`order of 0.005 inches in thickness. The sheet 50 includes
`on the bottom surface thereof, as shown in FIG. 2, a
`layer of adhesive 52 which is typically 0.001 inches in
`thickness of a screen permeable rubber-based material,
`typically solvated and cured by heat. The sheet 50 is
`bonded by the layer 52 in the manner shown in FIG. 3
`to the frame 70 which represents a rigid and flat or
`planar surface. Again referring to FIG. 2, the top sur
`face of sheet 50 contains a ?rst layer 54 of carbon or
`graphite material screened thereon having essentially
`the same thickness and width dimensions of the layer 40
`heretofore described with respect to the membrane
`portion of the switch. Comparing FIGS. 7 and 12 reveal
`that the orientation of the bar structures of the carbon
`layers 40 and 54 are at right angles to one another. Both
`FIGS. 7 and 12 are top plan views of the respective
`printed surfaces. When the surfaces are placed in over
`lying relationship, tail 48 of FIG. 7 overlies tail 64 of
`FIG. 12. Referring to FIG. 8, the carbon layer 54 on
`sheet 50 is shown to include bars 540, dots 54b, and
`separate switch areas 22 includes bars 54c which are
`essentially identical to the structures of carbon layer 40
`heretofore described, except with the direction or ori
`entation thereof.
`Next, as shown in FIGS. 2 and 9, a layer of the more
`conductive ink, referred to as the silver composition
`ink, is shown as 56 which is deposited on top of the
`carbon layer 54 but selectively at the spacer dot areas
`54b and additionally along conductive traces shown as
`56c and 56d in FIGS. 9 and 12. The screening effecting
`layer 56 is of a material and thickness and characteris
`tics essentially the same as heretofore described with
`respect to layer 42.
`Next, in accordance with the invention and referring
`to FIGS. 2 and 10, a dielectric screening, including a
`layer 58, is applied over the dots formed in layers 54 and
`56 and additionally over the conductive traces 56c. The
`dielectric layer formed thereby is shown with respect to
`the dots as 58a and with respect to the conductive traces
`as 58b. A dielectric utilized in an actual embodiment
`was comprised of a screen printable dielectric ink which
`is UV curable and available as a resin from W. R. Grace
`and Company. Such dielectric in a single pass repre
`sented a thickness of on the order of 0.0011 plus or
`minus 0.0001 inches in thickness and was of av width on
`45
`the order of 0.060 inches. By placing the dielectric
`spacer material on the ?xed or rigid side of the switch,
`namely on layer laminate 50, the stiffening effect of the
`dielectric, particularly as with respect to the conductive
`traces and the circuit runs 58b is made irrelevant to
`switch action, all movement taking place in the upper
`layer or in layer 30.
`To lend perspective to the foregoing, reference is
`made to FIG. 3 wherein a stylus or the ?ngers of an
`operator is shown depressing the upper layer 30 to
`effect a switch closure between the carbon traces 40a
`and 54a. It is to be noted how the various layers of
`carbon and silver ink and dielectric in the dot regions
`operate to de?ne a normally open switch but allowing
`closure through a very slight de?ection of the beam
`structure represented by the upper layer 30 supported
`by the essentially columnar stacking of the various lay
`ers. The open spacing between carbon traces 40a and
`54a is essentially the thickness of the two layers of silver
`ink plus the thickness of the dielectric layer as stacked
`in a given dot area. It has been found that the utilization
`of the silver ink layer over the carbon layer in the dots
`areas aids in de?ning the spacing in terms of consistency
`
`6
`over the area of the switch. It is contemplated that on
`occasion, and depending upon application, more spac
`ing can be provided by thicker coatings of either car
`bon, silver, or dielectric material, or in some cases, a
`second pass of one or several of these materials in the
`silk screening of the laminates. It is also contemplated
`that an added layer of adhesive may be applied to the
`dot areas to help in controlling delamination in use. It is
`worth noting that in the construction proposed here
`with respect to the present invention, the flexing and
`flexible part of the membrane switch, including the
`decorative or instruction coatings or layers, and the top
`layer or layer 30 is in an actual embodiment well under
`0.0l0 inches in thickness, and indeed the entire stack to
`the top of the surface of the rigid layer or lower frame
`70 is itself on the order of 0.010 inches in thickness or
`less.
`Having now disclosed and described in a preferred
`embodiment the principles of the invention with the
`intention that those skilled in the art may practice it in
`both method and apparatus, we now set forth its de?ni
`tion in the following claims.
`We claim:
`1. A membrane switch comprising:
`a ?rst sheet of ?exible insulating material bonded in
`selected areas to a ?at and planar surface of rela
`tively in?exible characteristics, said ?rst sheet
`being transparent and carrying visible symbols on
`the inner surface thereof formed by a ?rst layer of
`inks printed thereon and further including a barrier
`coating over such symbols to provide contrast
`therefore;
`a ?rst array of conductors printed on said barrier
`coating to de?ne a plurality of switch point areas
`extending over substantial portions of said ?rst
`sheet;
`a second array of conductors printed on the said
`in?exible surface to de?ne a plurality of switch
`point areas extending over substantial portions
`thereof;
`means connecting said ?rst and second arrays of con
`ductors to respective voltage sources; and
`spacer means formed by printing an array of spaced
`apart dots of a dielectric and insulating coating on
`top of at least one of the arrays of conductors in
`said de?ned switch point areas to hold said switch
`point areas normally apart until pressure is placed
`thereupon to deform said ?rst sheet and effect a
`switch closure between corresponding switch
`point areas of said arrays, the switch required a
`relatively low pressure to effect closure.
`2. The switch of claim 1 wherein said ?rst layer of ink
`is comprised of a plurality of areas of different colors to
`form symbols.
`3. The switch of claim 1 wherein said ?rst and second
`arrays of conductors are formed of inks of carbon deriv
`ative materials and wherein said means for connecting
`said ?rst and second arrays of conductors to respective
`voltage sources includes ?rst and second arrays of fur
`ther conductors, said further conductor arrays also
`including portions thereof providing bussing means for
`said ?rst and second arrays of conductors in each of said
`de?ned switch point areas, said further conductors
`being comprised of a signi?cantly higher conductive
`material than that of said conductors whereby any volt
`age drop from a respective voltage source to respective
`of said ?rst and second arrays of conductors is reduced.
`
`Exhibit 1012, Page 010
`
`

`
`4,818,827
`8
`across the face thereof, and including spacer means
`selectively located across the bulk of the area of said
`interior lower and upper surfaces, the method including
`the steps of:
`printing through a series of passes, decorative and
`colored symbols of dielectric materials on the inte
`rior lower surface of said ?exible sheet as a ?rst
`layer to provide visible indicia;
`printing a ?rst array of conductive materials forming
`half of a switch function on top of said ?rst layer on
`said ?rst sheet;
`printing a second array of conductive material form
`ing the other half of a switch function on said upper
`surface of said second sheet;
`providing means for connecting said ?rst and second
`arrays to respective voltage sources; and
`printing a layer of dielectric materials selectively on
`the second array as applied to said second sheet
`upper surface.
`10. The method of claim 9 wherein the method fur
`ther includes the step of printing a layer of adhesive in
`selected areas to at least one of the interior surfaces of
`said sheets to bond said sheets together.
`11. The method of claim 9 further including the steps
`of providing a rigid surface as a base for said switch and
`adhering the lower surface of the second sheet to said
`base.
`12. The method of claim 9 further including the step
`of printing a further conductive array formed of a mate
`rial more conductive than the materials of said arrays
`such that said further arrays provides the means for
`connecting said ?rst and second arrays to said respec
`tive voltage sources and further provides more conduc
`tive bussing means for commoning portions of the ?rst
`and second conductive arrays.
`Ill
`*
`it
`i!
`
`20
`
`25
`
`7
`4. The switch of claim 3 wherein said ?rst and second
`arrays of further conductors are disposed in selected
`spaced apart locations along said ?rst and second arrays
`of conductors, said locations corresponding to the loca
`tions of said dots of spacer means and underlying said
`dots of spacer means on said at least one ?rst and second
`array of conductor, thus increasing the height of the
`spacer means without increasing the thickness of the
`dielectric dots.
`5. The switch of claim 1 wherein the said ?rst sheet
`and the said planar surface are spaced apart by the said
`coating on the order of 0.002 thousands of an inch.
`6. The switch of claim 3 wherein the said thickness of
`the said ?rst sheet of material combined with the thick
`ness of said ?rst layer of ink, the barrier coating and the
`said ?rst array of conductors printed thereon is on the
`order of 0.006 to 0.009 inches in thickness and the spac
`ing from center to center of said spacer means is on the
`order of between 0.125 and 0.175 inches.
`7. The switch of claim 1 wherein said arrays of con
`ductors and said spacer means are screen printing on the
`respective ?rst sheet and in?exible surface.
`8. The switch of claim 1 wherein said switch point
`areas of said ?rst and second arrays of conductors com
`prise at least two elongated essentially parallel spaced
`conductors and a plurality of spaced crossbar conduc
`tors extending therebetween and essentially perpendic
`ular thereto, said elongated conductors of the ?rst array
`extending in a direction that is essentially perpendicular
`to the direction of the elongated conductors of the sec
`ond array.
`9. A method of manufacturing a membrane switch of
`a type characterized by having a ?rst flexible sheet of
`transparent material having an outside surface and an
`interior lower surface, said ?rst sheet of material being
`bonded at selective areas to a second sheet of material,
`said second sheet having an interior upper surface
`
`30
`
`=8
`
`45
`
`50
`
`55
`
`65
`
`Exhibit 1012, Page 011