as) United States
`a2) Patent Application Publication 10) Pub. No.: US 2010/0123670 Al
`(43) Pub. Date: May 20, 2010
`
`Philipp
`
`US 20100123670A1
`
`(54) TOUCH SCREEN SENSOR
`
`(75)
`
`Inventor:
`
`Harald Philipp, Hamble (GB)
`
`Correspondence Address:
`SCHWEGMAN, LUNDBERG & WOESSNER/
`ATMEL
`P.O. BOX 2938
`
`MINNEAPOLIS, MN 55402 (US)
`
`(73) Assignee:
`
`Atmel Corporation, San Jose, CA
`(US)
`
`(21) Appl. No.:
`
`12/421,696
`
`(22)
`
`Filed:
`
`Apr. 10, 2009
`
`Related U.S. Application Data
`
`(60) Provisional application No. 61/115,032,filed on Nov.
`15, 2008.
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`(2006.01)
`GO6F 3/041
`(2006.01)
`GO6F 19/00
`(2006.01)
`HOSK 3/30
`(52) US. C0 ecccccssscssssssssssssseere 345/173; 702/82; 29/832
`
`(57)
`
`ABSTRACT
`
`A two-dimensional touch sensor comprising a plurality of
`electrodes arranged in a mesh pattern on a substrate. Each
`electrode is formed by interconnected metaltraces, the metal
`being intrinsically opaque, but the metal traces being suffi-
`ciently narrow to be practically invisible. The metal traces
`have a width less than or equal to 10 um and occupyless than
`or equal to 5% of the area of each electrode. The electrodes
`can be deposited additively via a printing process,
`for
`example using copperas the metal. The narrow width of the
`tracks allows the film to be highly transparent, since the
`electric field used in capacitive touch screens can be madeto
`propagate with very low metal densities.
`
`
`
`SHOWING ELECTRODE SHAPES
`
`PETITIONERS
`
`Exhibit 1010, Page 1
`
`PETITIONERS
`Exhibit 1010, Page 1
`
`

`

`Patent Application Publication May 20,2010 Sheet 1 of 7
`
`US 2010/0123670 Al
`
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`Exhibit 1010, Page 2
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`

`

`Patent Application Publication May 20,2010 Sheet 2 of 7
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`US 2010/0123670 Al
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`

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`Patent Application Publication May 20,2010 Sheet 3 of 7
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`US 2010/0123670 Al
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`Exhibit 1010, Page 4
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`

`

`Patent Application Publication May 20,2010 Sheet 4 of 7
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`US 2010/0123670 Al
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`Exhibit 1010, Page 5
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`Exhibit 1010, Page 5
`
`

`

`Patent Application Publication May 20,2010 Sheet 5 of 7
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`US 2010/0123670 Al
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`Patent Application Publication May 20,2010 Sheet 6 of 7
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`US 2010/0123670 Al
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`Exhibit 1010, Page 7
`
`

`

`Patent Application Publication May 20,2010 Sheet 7 of 7
`
`US 2010/0123670 Al
`
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`Exhibit 1010, Page 8
`
`

`

`US 2010/0123670 Al
`
`May 20, 2010
`
`TOUCH SCREEN SENSOR
`
`BACKGROUND OF THE INVENTION
`
`[0001] The present inventionrelates to the manufacture and
`application of capacitive touch screen electrode layers by the
`use of single layer fine-line metal mesh electrodes printed
`onto a substrate. The method includes a simple waytoself-
`test the electrodes from a connectorso as to avoid the need for
`moreelaborate test methodologies.
`[0002] Most touch screens today, capacitive or otherwise,
`use a sputtered layer of Indium Tin Oxide (ITO) deposited
`onto a thin plastics film (such as PET film) or directly onto a
`glass layer. The ITO is uniformly deposited then etched using
`a subtractive process which involves numerousprocess steps.
`Finally, layers of silver ink and dielectric are used to make
`connections to the ITO onfilm or glass, which adds yet more
`process steps.
`[0003]
`ITO filmsare clear to about 92% (single layer), but
`have a relatively high resistance and are known to be quite
`fragile. A relatively high percentage of films become dam-
`aged during production, requiring an expensive and time-
`consumingtest stage. Also, ITO films are expensive and there
`are only a few suppliers who can competently manufacture
`such films, causing logistical problems for users of these
`films. Finally, Indium is a scarce metal which is increasingly
`in demand, yet production of this metal is limited by the few
`mines which produceit.
`[0004] Other materials can replace thesefilms, such as poly
`(3,4-ethylenedioxythiophene) or PEDOT conductive poly-
`mer. However PEDOTis not as optically clear as ITO, is
`difficult to deposit uniformly, and degrades rapidly under
`adverse environmental conditions.
`
`[0005] Therefore there is a need for a new material and/or
`method for producing touch screens which overcomes the
`abovelimitations.
`
`SUMMARYOF THE INVENTION
`
`[0006] The invention provides an improved touch sensor
`comprising a substrate with a sensitive area defined by a
`pattern of conductive electrodes arranged in a mesh pattern.
`[0007] The invention, in its most inexpensive form, com-
`prises the use of fine-line printed metal deposited additively
`via a printing process onto a PETlayer. It is now possible to
`inexpensively print metal traces that are highly conductive
`using copper, which are 10 um wideor less. The narrow width
`of these tracks allowsthe film to be highly transparent, since
`the electric field used in capacitive touch screens can be made
`to propagate with very low metal densities. In tests, ithas been
`foundthatfine line electrodes comprising less than 5% metal
`coverage of the total screen area, are nearly as effective in
`propagating fields as the solid surfaces they replace. In addi-
`tion to copper, other metals or alloys thereof with high elec-
`trical conductivity may also be used, for example silver or
`gold.
`[0008] Asaresult,a mesh offine metal lines of about 10 um
`width can be applied to a substrate such as PET film, which is
`98% clear, better than ITO. The metallines are so narrow as
`to be optically invisible. Also, the mesh configuration allows
`for robust performance, since a break in the metal is ‘cured’
`by alternate paths around the defect. Furthermore, copperis
`malleable unlike ITO and can be readily flexed or kinked
`
`without damage. Unlike PEDOT, fine line copper has no
`problems with environmental deterioration under normal
`conditions of anticipated use.
`[0009] The method applies to single-layer and two-layer
`film designs, the latter being commonly employed for higher
`resolution and for multi-touch sensing applications. Any
`numberof pattern designs can be used.
`[0010]
`Self-test is also optionally incorporated by the use of
`loop-back testing built into a film as will be described here-
`inafter.
`
`[0011] One aspect of the invention provides a two-dimen-
`sional
`touch sensor comprising a plurality of electrodes
`arranged in a pattern on a substrate, each electrode being
`formedof an interconnected mesh of metal traces, the metal
`being intrinsically opaque, but the metal traces being suffi-
`ciently narrow to be practically invisible.
`[0012] The metal traces preferably have a width less than or
`equal to 10 um,or alternatively less than or equal to 50 um, 40
`um, 30 um, 20 um or 5 pm.
`[0013] The metal traces preferably occupy less than or
`equal to 5% ofthe area of eachelectrode, or alternatively less
`than or equal to 10%, 8%, 6%, 4%, 2% or 1% of the area of
`each electrode.
`
`In some embodiments, the electrodes are arranged
`[0014]
`in a single layer. In other embodiments, the electrodes are
`arranged in two layers, the two layers being separated by a
`dielectric.
`
`[0015] Adjacent electrodes may be spacedapart by a plu-
`rality of islands also made of interconnected metaltraces, the
`metal traces of the islands being visually and electrically
`similar to the metal traces of the electrodes. These islands
`
`in-fill between electrodes to provide visual continuity.
`[0016]
`To provide a self-test capability, each electrode is
`preferably subdivided into upper and lowerparts, in that the
`metal traces from the upper and lower parts are connected
`only at a distal end ofthe electrode, there being no connection
`between metal traces in the upper and lower parts from the
`distal end to first and second proximal ends ofthe electrode.
`First and secondelectrical connections for each electrode are
`
`connected to respective first and second proximal ends
`thereof. If the electrode pattern is rotated through an angle of
`90 degrees the upper and lowerparts of each electrode may be
`referred to as the left and right parts respectively.
`[0017]
`In some embodiments, there are a plurality of X
`electrodes spaced apart by a plurality of Y electrodes. The
`second proximal end of each X electrodeis electrically con-
`nected to the first proximal end ofthe adjacent X electrode via
`a resistive element. The second proximalendof each Y elec-
`trode is electrically connectedto the first proximal end of the
`adjacent Y electrode.
`[0018] Another aspect of the invention provides a method
`of manufacturing a capacitive touch sensor, the method com-
`prising the steps of: providing a substrate; and depositing a
`plurality of electrodes on at least one side of the substrate,
`each electrode being formed of an interconnected mesh of
`metal traces, the metal being intrinsically opaque, but the
`metal traces being sufficiently narrow and of low visual den-
`sity so as to be practically invisible.
`[0019] Each electrode is advantageously subdivided into
`upper and lowerparts, in that the metal traces from the upper
`and lower parts are connected only at a distal end of the
`electrode, there being no connection between metal traces in
`the upper and lowerparts from the distal end to first and
`PETITIONERS
`
`Exhibit 1010, Page 9
`
`PETITIONERS
`Exhibit 1010, Page 9
`
`

`

`US 2010/0123670 Al
`
`May 20, 2010
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`which has been shown to emit copious amounts ofelectric
`second proximal ends of the electrode. The upper and lower
`field, almost the same as a solid electrode shape. A sparse
`parts of each electrode mayalso be referred to as left and right
`mesh allowsfor high optical clarity; if the traces are 10 um or
`parts respectively.
`less, and the mesh covers only 5% of the surface area, the
`[0020] The invention in another aspect covers a method of
`testing a capacitive touch sensor manufactured as above,
`optical properties will equal or exceed the best available ITO
`
`comprising: applyingafirst voltageto thefirst proximal end films which can only achieve 93% light transmission. Visu-
`of one of the plurality of electrodes while connecting the
`ally the film will only appear to have an extremely light shade
`proximalendsofall other electrodes to ground and measuring
`of gray, imperceptible to the untrained eye. At 10 microme-
`a secondvoltage at the second proximalendofthe one elec-
`ters, the metal tracesare invisible to the naked eye. A uniform
`trode; repeating the previousstepforall other electrodes; and
`density or uniform sparse distribution of these traces over the
`failing the sensor if the second voltage is anomalously low
`surface of a touch screen would not generate a noticeable
`compared to the first voltage for any of the electrodes, and
`visual pattern.
`passing the sensor otherwise. This provides self-test by the
`[0035] However,itis usually advisable to havea substantial
`use of loop-back testing around the loop formed by each
`gap betweentheelectrodesto allow for properfield propaga-
`‘split’ electrode.
`tion. These gaps can create a visual effect by showing up as
`lighter areas; as a consequence,it is desirable to ‘fill in’ these
`areas withfine lines ofa similar density as the electrode areas.
`Thecaveatis that thesefill areas should be disconnected from
`the electrodes and broken up into small islands or made up of
`isolated small metaltraces, so that the average density across
`the screen area is visually similar.
`[0036]
`FIG. 1A showsa basic pattern according to the
`invention, with horizontal bars of mesh labeled X which are
`connected together, to form oneofthefield electrode group-
`ings, and twosets of meshtriangles, one extending from each
`side, labeled YO and Y1. The bars X andtriangles Y0, Y1 are
`solid mesh electrodes 6. Also shown are spacer areas com-
`posed of disconnected mesh 4, having an areal density
`approximating the electrode mesh areas. Where cuts have
`been madein the meshto isolate each small cell, some metal
`tracking is added to compensate for the metal missing in the
`cuts. The pattern as shownstill has visual gap areas which can
`be fixed by the use of more judicious artwork design.
`[0037] Triangles YO, Y1 and bars X of metallic material 6
`are showninthefigure, together with spacer areas. The spacer
`areas may be unfilled or void of any metal pattern so as to
`allow electric fields to propagate optimally into an overlying
`panel during use. However, the metal mesh, while largely
`transparent, would under certain light conditions cause the
`gap or spacer areas to become more noticeable, even though
`the lines themselvesare toofine to be visible.
`
`For a better understanding of the invention and to
`[0021]
`show how the same may becarried into effect reference is
`now madeby wayof example to the accompanying drawings.
`[0022] FIG.1A showsa single-layer design according to an
`embodimentof the invention;
`[0023]
`FIG. 1B showsthe samepattern as in FIG. 1A, but
`with shading over the electrodes so as to aid the reader in
`viewing the electrode areas, for purposes of demonstration
`only;
`FIG. 2A shows a metal mesh configuration with
`[0024]
`self-test built in, using the loop-back principle;
`[0025]
`FIG. 2B showsthe electrode pattern shownin FIG.
`2A connected to a processor;
`[0026]
`FIG. 2C showsa flow chart for testing continuity of
`the electrode pattern shown in FIG. 2A;
`[0027]
`FIG. 2D showsa flow chart for testing continuity of
`the electrode pattern shown in FIG. 2A;
`[0028]
`FIG. 3A shows a 2-layer diamond pattern (or a
`1-layer pattern with cross-overs) implemented using the
`method, including the use ofself-test loop back paths;
`[0029]
`FIG. 3B showsthe electrode pattern shownin FIG.
`3A connected to a processor;
`[0030] FIG.4A showsthe samepattern as FIG. 2A,but with
`two termination resistors on the Y lines, which offers a
`method to reduce the connection count to the electrodes for
`
`self-test purposes;
`[0031]
`FIG. 4B showsthe electrode pattern shownin FIG.
`4A connected to a processor; and
`[0032]
`FIG. 4C showsa flow chart for testing continuity of
`the electrode pattern shown in FIG. 4A.
`
`DETAILED DESCRIPTION
`
`Processes have been recently developed which
`[0033]
`allow the printing of ultra-fine metal traces on plastic films
`and glass, as thin as 10 um or even less. The metals used
`include copper, which is highly conductive and has a darker
`color than other metals, for example chrome. The technology
`has been developed using standard photolithographic pro-
`cesses and can be used to mass producefilms on a roll-to-roll
`process for extremely low cost. No expensive,rare, or exotic
`materials are used in the manufacture of these metal traces.
`The technology has been developed specifically for use in
`micro-circuit applications, for example RFID tags, smart
`cards, displays, and thelike.
`[0034] These fine metal traces can also be used to develop
`field-emitting structures, using a sparse mesh configuration
`
`[0038] Accordingly, the spacer areas may be optionally
`filled with a metal pattern 4 that mimics the metal mesh
`electrode areas, but in such a manneras to provide an elec-
`trical discontinuity with the electrode areas. The spacer areas
`4 contain metalfilling that is ‘disconnected’ so that all the
`small metal segmentsare floating. The metal is shaped sothat
`the average density of the spacer areas is approximately the
`sameas the electrode areas so that visually the spacer areas
`blend in and cannot be distinguished from the electrodes.
`[0039]
`FIG. 1B shows graphically the electrodes them-
`selves using shading to outline the bars (X’s) andtriangles
`(Y’s). The un-shadedareas are the gap filler regions which
`contain disconnected islands of material matched in areal
`density to the electrodes soas to provide for visual continuity.
`[0040] Reliability of the electrodes is very important and
`may be compromised by micro-fractures of the electrodes or
`a defective metal printing process. Therefore, it is a preferred
`feature of the invention for electrical pathwaysof the elec-
`trode array to be tested from end to end. Using fine line
`connections and a split electrode technique,
`this can be
`readily accomplished, as shown in FIG. 2A and discussed
`below. Shownhere is the same basic pattern as shown in FIG.
`1A, howeverelectrodes are cut in such a wayas to create a ‘U’
`PETITIONERS
`
`Exhibit 1010, Page 10
`
`PETITIONERS
`Exhibit 1010, Page 10
`
`

`

`US 2010/0123670 Al
`
`May 20, 2010
`
`shaped conduction path; the first X bar andfirst Y triangle in
`this figure have the cuts highlighted (cut lines). Each elec-
`trode also has two connections, one for each endpoint of the
`“U’. In this way, an electrical current can be passed through
`each electrode shape to determine whetherthere is continuity
`or not. This is discussed further below.
`
`FIG. 2A shows ‘X’ lines, where it is common prac-
`[0041]
`tice to wire several electrodes together for the purpose of
`interpolation of the emitting field. Resistors are used (Rxa,
`Rxb, Rxc) to interconnect these electrodesin order to provide
`a potential gradient. For testing purposes, these resistors can
`be wired with split electrodes in such a wayas to beableto test
`all the ‘X’ electrodes in one step with no added external
`connection count. As shown, lines Xa and Xb loop through
`the four X electrodes using three resistors (Rxa, Rxb, Rxc), so
`that if any one electrode hasa failure, the electrical disconti-
`nuity and failure can be detected and the film and/or device
`rejected. FIG. 2A shows a metal mesh configuration with
`self-test built in, using the loop-backprinciple. In the case of
`“Y’ lines YO, Y1, it is typical that these are wired together as
`columns. In the case of FIG. 2A, there are two ‘columns’ of
`triangles, one left, and one right.In orderto test the continuity
`of these triangles with a minimum ofexternal connections,it
`is possible to take advantageof the fact that they are typically
`connected to each other anyway during use as a touch screen,
`by wiring the endsof thetriangles in series. FIG. 2A shows
`lines Y0a, Y05, and Y1a, Y1b;each pair being connected to
`its respective column using a series of connection of lines 2.
`By measuring continuity between the pair ends(i.e. between
`Y0a, Y06, and Y1a, Y16), all the triangles in a screen can be
`tested at the same time. This arrangement requires but one
`extra connection to the device per Y electrodeset; in the case
`of FIG. 2A,there are therefore only two more connections to
`be made than normal.
`
`It should also be noted that the arrangement shown
`[0042]
`in FIG. 2A can also be used to determine short circuits
`
`between adjacent ones of the electrodes, for example due to
`inadvertently deposited metal connecting an X electrode to a
`Y electrode. The mannerof such testing should be obvious to
`one skilled in theart.
`
`[0043] Using the method described above, the electrodes
`are sliced along their long axis and ‘looped back’atthe distal
`end from the connections, so that the touch screen processor
`can test the integrity ofall the metal mesh electrodes, for short
`circuits as well as open circuits. Only a few added connection
`lines or test points are required to do this.
`[0044]
`FIG. 2B showsthe electrode arrangement shown in
`FIG. 2A connected to a processor 10. The processor 10 could
`be a purpose built testing processor or could be the same
`processor that is used to operate the electrode pattern in a
`touch screen for example. A testing processor could be used
`during manufacture to test if the electrode pattern contains
`any short circuits or open circuits that would result in poor or
`no operation of the electrode pattern when usedas a part of a
`touch screen. If an open circuit or short circuit is detected
`during manufacture the electrode pattern could be discarded.
`Alternatively, a touch screen processor could test the elec-
`trode pattern during use, for example during start-up. If a
`short circuit or open circuit is detected in the electrode pat-
`tern, the user could be informed.
`[0045] The processor shownin FIG. 2B is shown asa single
`microprocessor, but it will be appreciated that several sepa-
`rate circuits could be combinedto form the processor, such as
`drive units, sense units including one or more ADCs and
`
`comparators. Each of the connections Y0a, Y05, Y1a, Y16,
`Xa and Xb ofthe processor 10 could be configured as inputs
`or outputs, or both depending onthetest strategy that is used.
`[0046] The presence of short and open circuits can be
`detected using the processor 10 with the steps shown in FIGS.
`2C and 2D.
`
`FIG. 2C showsthe steps to test the triangular elec-
`[0047]
`trodes Y0. In step S12, the bar electrodes (i.e. connections Xa
`and Xb) and triangular electrodes Y1 (i.e. connections Yla
`and Y15) are grounded. In step $14, a voltage is applied or
`connected to connection Y0a. In step $16, the voltage at
`connection Y06 is detected or measured.In step S18, if there
`is no voltage detected or measured at connectionY08,there is
`either an open circuit in the electrode pattern Y0 orthere is a
`closed circuit to the bar electrodes X or the triangular elec-
`trodes Y1. Thatis to say ifthe voltage measured at connection
`Y0é is anomalously low comparedto the voltage applied to
`connection Y0qa no voltage is measured or detected.
`[0048]
`To test the triangular electrodes Y1 the same steps
`are used as described above except the connectionsto trian-
`gular electrodes YO and Y1 are reversed. First, the bar elec-
`trodes (i.e. connections Xa and Xb)andtriangular electrodes
`Y0 (i.e. connections Y0a andY08)are grounded or connected
`to a ground connection. A voltage is then applied to Yla. The
`voltage is then measured at connection Y16. If there is no
`voltage detected at Y18, there is either an open circuit in the
`electrode pattern Y1 or there is a closed circuit to the bar
`electrodes X or the triangular electrodes Y0. Thatis to say if
`the voltage measured at connection Y14 is anomalously low
`comparedto the voltage applied to connectionY1a there is no
`voltage measured or detected at connection Y16.
`[0049]
`FIG. 2D showsthesteps to test the bar electrodes X.
`In step S20, the triangular electrodes Y0, Y1 (i.e. connections
`Y0a, Y06, Y1a and Y16)are grounded.In step $22, a voltage
`is applied or connected to connection Xa. In step S24, the
`voltage at connection Xb is measured. In step 826, if there is
`no voltage detected at connection Xb, there is either an open
`circuit in the electrode bar pattern X or there is a closed circuit
`to the triangularelectrodes Y0, Y1. Thatis to say ifthe voltage
`measured at connection Xb is anomalously low comparedto
`the voltage applied to connection Xa no voltage is measured
`or detected at connection Xb.
`
`Furthermore,in orderto test the resistors Rxa, Rxb,
`[0050]
`Rxc, a load resistor Rxd may be applied to terminal Xb to
`groundandthe voltage across it measured in a final step. Rxd
`serves to produce a voltage that is inversely related to the
`resistance of the other three resistors in accordance with
`Ohm/’s law, so that their values can be ascertained to ensure
`they are correct within a predefined tolerance band.
`[0051]
`It will be appreciated in the above, that the voltages
`could be equally applied to connections Xb, Y0b or Y1b
`respectively and the voltage detected at Xa, Y0a and Yla
`respectively. If the resistors Rxa, Rxb, Rxe are optionally
`tested using the method described aboveresistor Rxb would
`be connected to terminal Xa to ground.
`[0052]
`FIG. 3A shows a more conventional 2-layer geom-
`etry of electrodes composed of diamondpatterns as is well
`knowninthe art, but formed from an outline of the electrode
`shapes using fine line metal. With this pattern there are ver-
`tical columns32, 40 and horizontal rows 34, 42 of diamonds
`which are interconnected so as to form an interleaved elec-
`
`trode set in both the x and y axis. Some in-fill is used to
`increase the effective surface area as shown, using inward
`‘spikes’ of metal 38 emanating from each corner. This figure
`PETITIONERS
`
`Exhibit 1010, Page 11
`
`PETITIONERS
`Exhibit 1010, Page 11
`
`

`

`US 2010/0123670 Al
`
`May 20, 2010
`
`showsboth layers superimposed, howeverit should be under-
`stoodthat there is an insulating layer between the vertical and
`horizontal sets of diamond-shaped electrodes. As with FIG.
`2A,the electrode sets have two connections each and a loop-
`back structure 30 that permits testing for continuity and short
`circuits.
`
`FIG. 3B showsthe electrode arrangement shown in
`[0053]
`FIG. 3A connected to a processor 36. The processor 36 is
`similar in structure and operation to the processor shown in
`FIG. 2A.
`
`Thetest strategy shown in FIGS. 2C and 2D can be
`[0054]
`applied to the electrode pattern shown in FIG. 3B using the
`processor 36. For example,to test vertical column electrode
`32, the connections (X1a, X16, Y0a, Y06, Y1a and Y16)of
`the other electrodes are connected to ground. A voltage is
`applied or connected to connection X0qa and then the voltage
`at connection X05 is measured. If there is no voltage mea-
`sured at connection Xb,there is either an open circuit in the
`vertical column electrode 32 or there is a short circuit to one
`
`of the other electrodes. Thatis to say if the voltage measured
`at connection Xb is anomalously low comparedto the voltage
`applied to connection Xa no voltage is measured or detected
`at connection Xb.
`
`FIG. 4A shows a method of reducing the required
`[0055]
`number of added external connections required to perform
`the loop-backtest on the “Y’lines with regardto the electrode
`pattern of FIG. 2A. Resistors Ryt0 and Ryt1 are added to the
`endpoints of each set ofY triangles, and connected together to
`form connection Yt. This eliminates one of the Y line end-
`
`wires for each pair ofY triangle sets. The resistors are pref-
`erably of a high value so as not to cause interference with the
`sensing function of the electrodes. For example, the resistors
`can be 100 KQ orgreater.
`[0056]
`FIG. 4B showsthe electrode pattern shownin FIG.
`4A connected to processor 40. The processor 40 is similar in
`structure and operation to that described for the processor
`shown in FIG. 2B. However, as described above there is a
`reduced numberofconnections, namely connections Y05 and
`Y10 are replaced by a single connection Yt.
`[0057] The testing strategy for testing the bar electrodesis
`similar to that shown in the flow chart in FIG. 2D. For
`
`example, connections Yt, YO and Y1 are all connected to
`ground. A voltage is then applied to connection Xa. The
`voltage is then measured at Xb. If there no voltage measured
`at connection Xb, there is either an open circuit in the bar
`electrode pattern or there is a closed circuit to the triangular
`electrodes. That is to say if the voltage measured at connec-
`tion Xb is anomalously low comparedto the voltage applied
`to connection Xa no voltage is measured or detected at con-
`nection Xb.
`
`[0058]
`involves:
`
`Thetest procedurefor testing the Y lines of FIG. 4A
`
`4) ground YO while holding the voltage on Yt,
`
`1) groundall X connections, then,
`2) put a voltage on connection Yt, then,
`3) measure the voltage on each of YO and Y1,
`
`[0059]
`[0060]
`[0061]
`then,
`[0062]
`then,
`5) measure the output ofY1.
`[0063]
`Ifin step 3 there is no voltage on either YO or Y1,
`[0064]
`there is a fault, either due to a short circuit from a Y electrode
`to an X electrode or an open circuit in the Y electrode pattern.
`If in step 5 there is no voltage on Y1, there is a short circuit
`
`between Y1 and Y0. The above sequence tests all known
`combinationsofpossible faults.
`[0065] The steps described abovefor testing the Y lines are
`summarized in Steps S1 to S5 in FIG. 4C. It will be appreci-
`ated thatafter steps 3 or 5 (i.e. S3 or S5) above the electrode
`pattern could be discarded. Thatis to say if the voltage mea-
`sured on connection Y0 or Y1 in step 3, or Y1 in step 5 is
`anomalously low comparedto the voltage applied to connec-
`tion Yt in step 2 or 4, the electrode pattern is considered to
`have failed and could be discarded, otherwise the sensor
`baring the electrode pattern is deemed to have passed.
`[0066] The invention can also be used to make resistive
`screens and electroluminescent (EL) lamps, because the
`metal density is high enough that these applications canstill
`function but with enhanced transparency when compared
`with ITO or PEDOTbasedelectrodes.
`
`[0067] Different sensing techniques may be employed with
`the invention to determine changes in capacitance and the
`presence or absence of a user in proximity with the touch
`sensor. For example, the apparatus and methods described in
`USS. Pat. No. 6,466,036 and U.S. Pat. No. 6,452,514 may
`each be employed with the invention and are incorporated
`herein in their entirety.
`
`Whatis claimedis:
`
`1. A two-dimensional touch sensor comprising a plurality
`of electrodes arranged in a pattern on a substrate, each elec-
`trode being formed ofan interconnected mesh ofmetaltraces,
`the metal being intrinsically opaque, but the metal traces
`being sufficiently narrow to be practically invisible.
`2. The two-dimensional sensor of claim 1, wherein the
`metal traces have a width less than or equal to 10 um.
`3. The two-dimensional sensor of claim 1, wherein the
`metal traces occupy less than or equal to 5% of the area of
`each electrode.
`
`4. The two-dimensional sensor of claims 1, wherein the
`electrodes are arranged in a single layer.
`5. The two-dimensional sensor of claims 1, wherein the
`electrodes are arranged in twolayers separated by a dielectric.
`6. The two-dimensional touch sensor of claim 1, wherein
`adjacent electrodes are spaced apart by a plurality of islands
`also made of interconnected metal traces, the metal traces of
`the islands being visually and electrically similar to the metal
`traces ofthe electrodes.
`7. The two-dimensional touch sensor of claim 1, wherein
`each electrode is subdivided into upper and lowerparts, in
`that the metal traces from the upper and lower parts are
`connected only at a distal end of the electrode, there being no
`connection between metaltraces in the upper and lowerparts
`from the distal end to first and second proximal ends of the
`electrode.
`8. The two-dimensional touch sensor of claim 7, further
`comprising first and second electrical connections for each
`electrode connected to respective first and second proximal
`ends thereof.
`
`9. The two-dimensional touch sensor of claim 8, wherein
`the electrodes comprise a plurality of X electrodes spaced
`apart by a plurality ofY electrodes;
`wherein the second proximal end of each X electrode is
`electrically connected to the first proximal end of the
`adjacent X electrode via a resistive element; and
`wherein the second proximal end of each Y electrode is
`electrically connected to the first pr