(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2010/0123670 A1
`Philipp
`(43) Pub. Date:
`May 20, 2010
`
`US 2010.01.23670A1
`
`(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
`Provisional application No. 61/115,032, filed on Nov.
`15, 2008.
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`G06F 3/04
`(2006.01)
`G06F 9/00
`(2006.01)
`H05K 3/30
`(52) U.S. Cl. .............................. 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 metal traces, 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 10um and occupy less than
`or equal to 5% of the area of each electrode. The electrodes
`can be deposited additively via a printing process, for
`example using copper as 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 made to
`propagate with very low metal densities.
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`PANASONIC EX1010, page 001
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`

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`Patent Application Publication May 20, 2010 Sheet 1 of 7
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`PANASONIC EX1010, page 002
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`Patent Application Publication May 20, 2010 Sheet 2 0f 7
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`PANASONIC EX1010, page 003
` IPR2021-01115
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`Patent Application Publication May 20, 2010 Sheet 3 of 7
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`US 2010/O123670 A1
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`PANASONIC EX1010, page 004
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`Patent Application Publication May 20, 2010 Sheet 4 of 7
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`US 2010/O123670 A1
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`Patent Application Publication May 20, 2010 Sheet 5 of 7
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`Patent Application Publication
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`May 20, 2010 Sheet 6 of 7
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`Patent Application Publication May 20, 2010 Sheet 7 of 7
`
`US 2010/O123670 A1
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`US 2010/0123670 A1
`
`May 20, 2010
`
`TOUCH SCREEN SENSOR
`
`BACKGROUND OF THE INVENTION
`
`0001. The present invention relates 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 way to self
`test the electrodes from a connectorso as to avoid the need for
`more elaborate 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 numerous process steps.
`Finally, layers of silver ink and dielectric are used to make
`connections to the ITO on film or glass, which adds yet more
`process steps.
`0003 ITO films are 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
`consuming test 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 produce it.
`0004 Other materials can replace these films, such as poly
`(3,4-ethylenedioxythiophene) or PEDOT conductive poly
`mer. However PEDOT is 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
`above limitations.
`
`SUMMARY OF 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 PET layer. It is now possible to
`inexpensively print metal traces that are highly conductive
`using copper, which are 10um wide or less. The narrow width
`of these tracks allows the film to be highly transparent, since
`the electric field used in capacitive touchscreens can be made
`to propagate with very low metal densities. In tests, it has been
`found that fine 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. As a result, a mesh offine metal lines of about 10um
`width can be applied to a substrate such as PET film, which is
`98% clear, better than ITO. The metal lines 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, copper is
`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
`number of 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
`formed of 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 10um, or alternatively less than or equal to 50 um, 40
`um, 30 um, 20 Lim or 5um.
`0013 The metal traces preferably occupy less than or
`equal to 5% of the area of each electrode, or alternatively less
`than or equal to 10%, 8%, 6%, 4%, 2% or 1% of the area of
`each electrode.
`0014. In some embodiments, the electrodes are arranged
`in a single layer. In other embodiments, the electrodes are
`arranged in two layers, the two layers being separated by a
`dielectric.
`00.15 Adjacent electrodes may be spaced apart by a plu
`rality of islands also made of interconnected metal traces, 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 lower parts, 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 lower parts from the
`distal end to first and second proximal ends of the electrode.
`First and second electrical 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 lower parts 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 electrode is electrically con
`nected to the first proximal end of the adjacent X electrode via
`a resistive element. The second proximal end of each Y elec
`trode is electrically connected to 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 lower parts, 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 lower parts from the distal end to first and
`
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`US 2010/0123670 A1
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`May 20, 2010
`
`second proximal ends of the electrode. The upper and lower
`parts of each electrode may also be referred to as left and right
`parts respectively.
`0020. The invention in another aspect covers a method of
`testing a capacitive touch sensor manufactured as above,
`comprising: applying a first voltage to the first proximal end
`of one of the plurality of electrodes while connecting the
`proximal ends of all other electrodes to ground and measuring
`a second Voltage at the second proximal end of the one elec
`trode; repeating the previous step for all other electrodes; and
`failing the sensor if the second Voltage is anomalously low
`compared to the first Voltage for any of the electrodes, and
`passing the sensor otherwise. This provides self-test by the
`use of loop-back testing around the loop formed by each
`split electrode.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0021
`For a better understanding of the invention and to
`show how the same may be carried into effect reference is
`now made by way of example to the accompanying drawings.
`0022 FIG. 1A shows a single-layer design according to an
`embodiment of the invention;
`0023 FIG. 1B shows the same pattern 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;
`0024 FIG. 2A shows a metal mesh configuration with
`self-test built in, using the loop-back principle;
`0025 FIG. 2B shows the electrode pattern shown in FIG.
`2A connected to a processor,
`0026 FIG. 2C shows a flow chart for testing continuity of
`the electrode pattern shown in FIG. 2A;
`0027 FIG. 2D shows a 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 of self-test loop back paths;
`0029 FIG. 3B shows the electrode pattern shown in FIG.
`3A connected to a processor,
`0030 FIG. 4A shows the same patternas 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 shows the electrode pattern shown in FIG.
`4A connected to a processor, and
`0032 FIG. 4C shows a flow chart for testing continuity of
`the electrode pattern shown in FIG. 4A.
`
`DETAILED DESCRIPTION
`0033 Processes have been recently developed which
`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 produce films 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 the like.
`0034. These fine metal traces can also be used to develop
`field-emitting structures, using a sparse mesh configuration
`
`which has been shown to emit copious amounts of electric
`field, almost the same as a Solid electrode shape. A sparse
`mesh allows for high optical clarity; if the traces are 10um or
`less, and the mesh covers only 5% of the surface area, the
`optical properties will equal or exceed the best available ITO
`films which can only achieve 93% light transmission. Visu
`ally the film will only appear to have an extremely light shade
`of gray, imperceptible to the untrained eye. At 10 microme
`ters, the metal traces are invisible to the naked eye. A uniform
`density or uniform sparse distribution of these traces over the
`Surface of a touch screen would not generate a noticeable
`visual pattern.
`0035 However, it is usually advisable to have a substantial
`gap between the electrodes to allow for proper field propaga
`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 with fine lines of a similar density as the electrode areas.
`The caveat is that these fill areas should be disconnected from
`the electrodes and broken up into Small islands or made up of
`isolated Small metal traces, so that the average density across
`the screen area is visually similar.
`0036 FIG. 1A shows a basic pattern according to the
`invention, with horizontal bars of mesh labeled X which are
`connected together, to form one of the field electrode group
`ings, and two sets of mesh triangles, one extending from each
`side, labeledY0 and Y1. The bars X and triangles 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 made in the mesh to isolate each Small cell. Some metal
`tracking is added to compensate for the metal missing in the
`cuts. The pattern as shown still has visual gap areas which can
`be fixed by the use of more judicious artwork design.
`0037 Triangles Y0, Y1 and bars X of metallic material 6
`are shown in the figure, 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 themselves are too fine to be visible.
`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 manner as to provide an elec
`trical discontinuity with the electrode areas. The spacer areas
`4 contain metal filling that is disconnected so that all the
`Small metal segments are floating. The metal is shaped so that
`the average density of the spacer areas is approximately the
`same as 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) and triangles
`(Y’s). The un-shaded areas are the gap filler regions which
`contain disconnected islands of material matched in areal
`density to the electrodes so as 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 pathways of 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. Shown here is the same basic pattern as shown in FIG.
`1A, however electrodes are cut in such away as to create a “U”
`
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`US 2010/0123670 A1
`
`May 20, 2010
`
`shaped conduction path; the first X bar and first 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 whether there is continuity
`or not. This is discussed further below.
`0041
`FIG. 2A shows X' lines, where it is common prac
`tice to wire several electrodes together for the purpose of
`interpolation of the emitting field. Resistors are used (Rxa,
`Rxb, Rxc) to interconnect these electrodes in order to provide
`a potential gradient. For testing purposes, these resistors can
`be wired with split electrodes in such away as to be able to 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 has a 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-back principle. In the case of
`Y lines Y0. 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 order to test the continuity
`of these triangles with a minimum of external connections, it
`is possible to take advantage of the fact that they are typically
`connected to each other anyway during use as a touch screen,
`by wiring the ends of the triangles in series. FIG. 2A shows
`lines Y0a, Y0b, 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, Y0b, and Y1a, Y1b), all the triangles in a screen can be
`tested at the same time. This arrangement requires but one
`extra connection to the device perY electrode set; in the case
`of FIG. 2A, there are therefore only two more connections to
`be made than normal.
`0042. It should also be noted that the arrangement shown
`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
`Yelectrode. The manner of such testing should be obvious to
`one skilled in the art.
`0043. Using the method described above, the electrodes
`are sliced along their long axis and looped back at the distal
`end from the connections, so that the touch screen processor
`can test the integrity of all 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 shows the 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 used as 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 shown in FIG.2B is shown as a single
`microprocessor, but it will be appreciated that several sepa
`rate circuits could be combined to form the processor, Such as
`drive units, sense units including one or more ADCs and
`
`comparators. Each of the connections Y0a, Y0b, Y1a, Y1b,
`Xa and Xb of the processor 10 could be configured as inputs
`or outputs, or both depending on the test 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.
`0047 FIG. 2C shows the steps to test the triangular elec
`trodes Y0. In step S12, the bar electrodes (i.e. connections Xa
`and Xb) and triangular electrodes Y1 (i.e. connections Y1a
`and Y1b) are grounded. In step S14, a Voltage is applied or
`connected to connection Y0a. In step S16, the voltage at
`connection Y0b is detected or measured. In step S18, if there
`is no voltage detected or measured at connectionY0b, there is
`either an open circuit in the electrode pattern Y0 or there is a
`closed circuit to the bar electrodes X or the triangular elec
`trodes Y1. That is to say if the voltage measured at connection
`Y0b is anomalously low compared to the voltage applied to
`connection YOa no Voltage is measured or detected.
`0048. To test the triangular electrodes Y1 the same steps
`are used as described above except the connections to trian
`gular electrodes Y0 and Y1 are reversed. First, the bar elec
`trodes (i.e. connections Xa and Xb) and triangular electrodes
`Y0 (i.e. connections Y0a and Y0b) are grounded or connected
`to a ground connection. A Voltage is then applied to Y1a. The
`voltage is then measured at connection Y1b. If there is no
`voltage detected at Y1b, 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. That is to say if
`the Voltage measured at connection Y1b is anomalously low
`compared to the Voltage applied to connection Y1a there is no
`voltage measured or detected at connection Y1b.
`0049 FIG. 2D shows the steps to test the bar electrodes X.
`In step S20, the triangular electrodes Y0.Y1 (i.e. connections
`Y0a, Y0b, Y1a and Y1b) are grounded. In step S22, a voltage
`is applied or connected to connection Xa. In step S24, the
`voltage at connection Xb is measured. In step S26, if there is
`no Voltage detected at connection Xb, there is either an open
`circuit in the electrode bar pattern Xorthere is a closed circuit
`to the triangular electrodes Y0.Y1. That is to say if the voltage
`measured at connection Xb is anomalously low compared to
`the Voltage applied to connection Xano Voltage is measured
`or detected at connection Xb.
`0050. Furthermore, in order to test the resistors Rxa, Rxb,
`Rxc, a load resistor Rxd may be applied to terminal Xb to
`ground and the 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 Y1a
`respectively. If the resistors Rxa, Rxb., RXc are optionally
`tested using the method described above resistor Rxb would
`be connected to terminal Xa to ground.
`0.052
`FIG. 3A shows a more conventional 2-layer geom
`etry of electrodes composed of diamond patterns as is well
`known in the art, but formed from an outline of the electrode
`shapes using fine line metal. With this pattern there are ver
`tical columns 32, 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
`
`PANASONIC EX1010, page 011
` IPR2021-01115
`
`

`

`US 2010/0123670 A1
`
`May 20, 2010
`
`shows both layers superimposed, however it should be under
`stood that 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.
`0053 FIG. 3B shows the electrode arrangement shown in
`FIG. 3A connected to a processor 36. The processor 36 is
`similar in structure and operation to the processor shown in
`FIG. 2A
`0054) The test strategy shown in FIGS. 2C and 2D can be
`applied to the electrode pattern shown in FIG. 3B using the
`processor 36. For example, to test vertical column electrode
`32, the connections (X1a, X1b, Y0a, Y0b, Y1a and Y1b) of
`the other electrodes are connected to ground. A Voltage is
`applied or connected to connection X0a and then the Voltage
`at connection X0b 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. That is to say if the voltage measured
`at connection Xb is anomalously low compared to the Voltage
`applied to connection Xano Voltage is measured or detected
`at connection Xb.
`0055 FIG. 4A shows a method of reducing the required
`number of added external connections required to perform
`the loop-back test on the Y lines with regard to the electrode
`pattern of FIG. 2A. Resistors Ryto and Ryt1 are added to the
`endpoints of each set of Ytriangles, and connected togetherto
`form connection Yt. This eliminates one of the Y line end
`wires for each pair of Y 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 KS2 or greater.
`0056 FIG. 4B shows the electrode pattern shown in 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 number of connections, namely connections Y0b and
`Y1b are replaced by a single connection Yt.
`0057 The testing strategy for testing the bar electrodes is
`similar to that shown in the flow chart in FIG. 2D. For
`example, connections Yt, Y0 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 compared to the Voltage applied
`to connection Xano Voltage is measured or detected at con
`nection Xb.
`0058. The test procedure for testing the Y lines of FIG. 4A
`involves:
`0059 1) ground all X connections, then,
`0060 2) put a voltage on connection Yt, then,
`0061 3) measure the voltage on each of Y0 and Y1,
`then,
`0062 4) ground Y0 while holding the voltage on Yt,
`then,
`0063 5) measure the output of Y1.
`0064. If in step 3 there is no voltage on either Y0 or Y1,
`there is a fault, either due to a short circuit from a Yelectrode
`to an X electrode or an open circuit in the Yelectrode 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
`combinations of possible faults.
`0065. The steps described above for testing the Y lines are
`summarized in Steps S1 to S5 in FIG. 4C. It will be appreci
`ated that after steps 3 or 5 (i.e. S3 or S5) above the electrode
`pattern could be discarded. That is to say if the Voltage mea
`sured on connection Y0 or Y1 in step 3, or Y1 in step 5 is
`anomalously low compared to 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 can still
`function but with enhanced transparency when compared
`with ITO or PEDOT based electrodes.
`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
`U.S. 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.
`What is claimed is:
`1. A two-dimensional touch sensor comprising a plurality
`of electrodes arranged in a pattern on a Substrate, each elec
`trode being formed of an interconnected mesh of metal traces,
`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 Lum.
`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 two layers 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 of the electrodes.
`7. The two-dimensional touch sensor of claim 1, wherein
`each electrode is Subdivided into upper and lower parts, 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 lower parts
`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 of Y electrodes;
`wherein the second proximal end of each X electrode is
`electrically connected to the first proximal end of th