United States Patent [19]
`Denley
`
`[11]
`. [45]
`
`4,391,845
`Jul. 5, 1983
`
`[54] METHOD OF MAKING A MEMBRANE
`SWITCH
`[75] Inventor: Ronald S. Denley, Woodstock, Ill.
`[73] Assigneez Oak Industries Inc.’ Rancho
`Bemardo’ Cam
`
`[21] APPL NO‘I 323,023
`[22] Filed:
`No“ 19’ 1981
`
`}
`[21] gglt. (gi ....................................... “£2.7Hg81'l':2171/
`[ 2]
`'S'
`'
`59
`goo/5AA:
`’
`'
`’
`-
`’ zoo/292’
`[58] Field of Search ........... .. 29/622; 200/159 B, 5 A,
`ZOO/292; 427/58, 96’ 282’ 2071
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,995,126 11/1976 Larson ...................... .. 200/159 B X
`4,184,043 1/1980 Hildering .......... ..
`427/282 X
`4,317,013 2/1982 Larson ...... ..
`200/5 A
`4,320,573 3/1982 Larson .......................... .. 200/5 A X
`Primary Examiner-John D. Smith
`Assistant Examiner-Bernard F. Plantz
`Attorney. Agent, or Firm-Kinzer, Plyer, Dorn &
`McEachran
`
`ABSTRACT‘
`[57]
`This invention relates to a method of fabricating a mem
`brane switch of the type having a substrate, a ?exible
`membrane, electrical conductors formed on the mem
`brane and substrate, and an mtervenmgspacer between
`the sets of conductors. The conductors include a plural
`ity of switch sites which are in facing relation to de?ne
`a speci?c switch. The spacer means comprises a plural
`ity of individual spacer areas which are located remote
`from the Switch Sites_ The manufacturing method uses a
`multiple pass screen printing operation. During the ?rst
`pass a set of conductors is formed from conductive ink
`t?“ f‘ther ?le membra’: ‘zrlsubstmft-iiflw’ ‘mm ‘b?
`IT'S screening pass a . irs ayer or e ‘spacer areas is
`formed from the same conductive material as the set of
`conductors. On subsequent screening passes additional
`layers are deposited on the spacer areas to build up the
`thickness of the areas so that the spacer thickness is
`greater than that of the conductors. The location of the
`spacer areas and the formation of the ?rst layer of the
`, spacer areas from conductive material permits elimina
`tion of one screening pass and subsequent registration
`problems.
`‘
`
`4 Claims, 4 Drawing Figures
`
`Global Touch Solutions, LLC
`Exhibit 2003
`Microsoft Corp. et al. v. Global Touch Solutions, LLC
`IPR2015-01149
`Page 1 of 4
`
`

`
`' US. Patent
`
`Jul. 5, 1983
`
`4,391,845
`
`/Z VYIIIIIII'IIAY’II'III?II4
`
`Global Touch Solutions, LLC
`Exhibit 2003
`Microsoft Corp. et al. v. Global Touch Solutions, LLC
`IPR2015-01149
`Page 2 of 4
`
`

`
`1
`
`METHOD OF MAKING A MEMBRANE SWITCH
`
`LII
`
`SUMMARY OF THE INVENTION
`This invention relates to membrane switches and is
`particularly directed to a method of fabricating a mem
`brane switch using a multiple pass screen printing oper
`ation.
`A primary object of the present invention is the elimi
`nation of one of the multiple passes necessary to make a
`membrane switch by the screen printing process.
`Another object is a membrane switch formed by
`screen printing wherein the pressure needed‘to actuate
`the switch can be varied by controlling the size and
`location of the spacer means.
`'
`Another object is a membrane switch having a spacer
`which can be made of electrically conductive material.
`Other objects will appear in the following speci?ca
`tion and drawings. ’
`'
`
`4,391,845
`2
`forming complicated arrangements of conductors.
`While the conductors can be readily formed by screen
`printing, it is somewhat more dif?cult to apply the
`spacer by screening techniques. This is due to the fact
`that the spacer must have a greater thickness than the
`electrical conductors in order to perform its function of
`holding the conductors apart. The actuation force of
`the switch can be increased by increasing the spacer
`thickness. Variable spacer thickness can be accom
`plished by a multiple pass screen printing operation.
`The spacer thickness is gradually built up in several
`layers, one layer being applied during each screening
`pass. However, multiple-pass screening adds to the time
`and the cost of making a membrane switch. The present
`invention permits elimination of one screening pass by
`forming both the set of conductors and the ?rst layer of
`the spacer means during the initial screening pass. Thus
`the ?rst layer of the spacer means is formed of the same
`conductive material as the electrical conductors. This
`can be done without shorting the switch sites 16 or the
`leads 18 by placing the spacer areas 26 at locations
`remote from the switch sites. As can be seen in FIG. 1,
`the spacer areas 26 are arrayed in a four corner pattern
`which surrounds the switch sites 16 but does not
`contact either the electrodes 20 or their leads 18. Thus,
`the fact that the spacer areas are themselves conductive
`does not affect the electrical circuit because the areas 26
`are spaced from the conductors. The gap between a
`spacer area and an electrode is preferably on the order
`20 mils.
`FIG. 2 illustrates how the conductors and spacer
`‘areas are applied to the substrate 12. During a ?rst
`screening pass the leads 18, the electrodes 20 and a ?rst
`layer 28 of the spacer areas 26 are formed. During sub
`sequent passes additional layers 30 are formed on top of
`the ?rst layer 28 to build up the ?nal thickness of the
`spacer area 26. In FIG. 2 there are four layers at each
`spacer area. The additional layers 30 can be formed of
`the same conductive ink used to form av ?rst layer. Or
`the additional layers 30 could be formed of non~conduc~
`tive ink. A further option is to form the top layer of the
`spacer area of an adhesive material to hold the mem
`brane in place. While the above discussion has assumed
`the spacer areas are formed on the substrate, it will be
`understood that the spacer areas could also be applied
`to the underside of the membrane.
`While FIGS. 1 and 2 show a switch site in the form of
`a pair of spaced electrodes 20 and a shorting bar 24 in
`spaced, facing relation, it will be understood that other
`types of conductor con?gurations could be used. FIG.
`4 shows three variations of switch sites ' with corre
`sponding spacer con?gurations. Switch 32 has a central
`electrode 34 and outer spacer bars 36. Switch 38 has a
`t-shaped electrode 40 and spacer areas 42. Switch 44 has
`a box shaped electrode 46 with four comer spacer areas _
`48 and the central spacer area 50. It will be understood
`that each of these switches would have a corresponding
`electrode in facing relation on the underside , of the
`membrane. These electrodes are shown in FIG. 3. Elec
`trodes 34A, 40A and 46A cooperate with electrodes 34,
`40 and 46 to complete the switches. The accompanying
`leads are not shown. Each of these switch and spacer
`con?gurations can be formed by making a ?rst screen~
`ing pass to form the electrode and a ?rst layer of the
`spacer areas. The spacer areas are then built up by mak
`ing additional screening passes. While a preferred form
`of the invention has been shown and described it will be
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a plan view of a membrane switch with a
`portion of the membrane cut away to show the underly
`ing components.
`25
`FIG. 2 is a section taken substantially along line 2-2
`of FIG. 1.
`FIG. 3 is a plan view of the underside of ‘a membrane
`showing alternate con?gurations for the switch sites.
`FIG. 4 is a plan view of a substrate, showing the
`alternate switch sites and spacer means to be used in
`conjunction with the membrane of FIG. 3.
`
`30
`
`35
`
`45
`
`.DESCRIPTION OF A PREFERRED
`EMBODIMENT
`This invention is concerned with membrane switches
`and a method of making them. FIG. 1 illustrates a mem
`brane switch 10. The switch has an electrically insula- '
`tive substrate 12 which may be either rigid or ?exible. A
`?rst set of electrical conductors 14 is formed on the
`substrate- 12. The conductors include a plurality of
`40
`switch sites 16 with connecting leads 18. In the illus
`trated embodiment the switch sites 16 comprise a pair of
`spaced electrodes 20.
`Overlying thesubstrate is a ?exible membrane 22.
`The membrane can be made of any ?exible sheet mate
`rial for example polyester sold by Dupont under the
`trademark “Mylar”. The membrane is on the order of 5
`mils thick. A ‘second set of electrical conductors is
`formed on the underside of the membrane. In the illus
`trated embodiment the second set of conductors com
`prises a plurality of switch sites 24 which are shorting
`bars. When the switch is actuated the shorting bars
`contact the spaced electrodes 20, thereby shorting the
`electrodes and closing the switch. When the actuating
`pressure is released the shorting bar returns to its nor
`mal position, spaced from the electrodes.
`The electrical conductors are normally held in
`spaced, non-contacting relation' by a spacer means. The
`spacer means includes a plurality of spacer areas 26
`formed either on the membrane or substrate. In FIG. 1
`the spacer areas 26 are on the substrate 12. The spacer
`areas are located remote from the switch sites 16 and 24.
`There is no contact between the spacer areas and the
`electrical conductors.
`A well-known method of forming the conductors on
`the membrane and substrate is to screen print a conduc
`tive ink in the desired con?guration and then allow the
`ink to dry. This method is particularly advantageous for
`
`Global Touch Solutions, LLC
`Exhibit 2003
`Microsoft Corp. et al. v. Global Touch Solutions, LLC
`IPR2015-01149
`Page 3 of 4
`
`

`
`4,391,845
`3
`4
`(a) forming one of the sets of conductors by screening
`understood that many alterations and could be made
`thereto. Therefore the invention is not to be limited to
`a conductive material on the‘ substrate or mem
`the speci?c forms illustrated.
`brane in a ?rst screening pass;
`(b) forming a ?rst layer of the spacer areas from the’
`I claim:
`conductive material during the ?rst screening pass;
`1. In a method of making a component of a membrane
`(0) forming additional layers of the spacer areas by
`switch in a multiple-pass screen printing process, the
`subsequent screening passes which deposit material
`membrane switch being of the type having a substrate,
`only on the spacer areas so that the spacer means
`a ?exible membrane, a ?rst set of electrical conductors
`thickness is greater than that of the conductors.
`on the substrate, a second set of electrical conductors on
`2. The method of claim 1 wherein the spacer material
`the membrane, the conductor sets including a plurality
`deposited during said subsequent screening passes is
`of switch sites in facing relation, and spacer means nor
`electrically conductive.
`mally holding the conductor sets in spaced, non-con
`3. The method of claim 1 wherein the spacer material
`tacting relation7 the spacer means including a plurality
`deposited during said subsequent screening passes is
`of spacer areas on either the membrane or substrate at
`electrically non-conductive.
`‘locations remote from the ?rst and second sets of elec
`4. The method of claim 1 further including the step of
`trical conductors, the improved method comprising the
`applying adhesive material to the spacer areas.
`steps of:
`it
`t
`I!
`it
`i
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`Global Touch Solutions, LLC
`Exhibit 2003
`Microsoft Corp. et al. v. Global Touch Solutions, LLC
`IPR2015-01149
`Page 4 of 4