(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2007/0008299 A1
`(43) Pub. Date:
`Jan. 11, 2007
`Hristov
`
`US 20070008299Al
`
`TWO-DIMENSIONAL POSITION SENSOR
`
`(52) US. Cl. ............................................................ .. 345/173
`
`(57)
`
`ABSTRACT
`
`A capacitive position sensor for determining the position of
`an object along ?rst and second directions is described. The
`sensor comprises a substrate having an arrangement of
`electrodes mounted on a single surface thereof. The elec
`trodes are arranged so as to de?ne an array of sensing cells
`arranged in columns and roWs to form a sensing area. Each
`of the sensing cell including a column sensing electrode and
`a roW sensing electrode With the column sensing electrodes
`of sensing cells in the same column being electrically
`coupled together and the roW sensing electrodes of sensing
`cells in the same roW also being electrically coupled
`together. RoW sensing electrodes of sensing cells at oppos
`ing ends of at least one of the roWs are connected together
`by an electrical connection made outside of the sensing area
`so that there is no requirement for electrical connections to
`cross Within the sensing area, thus providing a capacitive
`position sensor having a sensing area With electrodes on
`only one side of a substrate.
`
`(54)
`
`(75)
`
`(73)
`
`(21)
`
`(22)
`
`Inventor: Luben Hristov, Southampton (GB)
`
`Correspondence Address:
`DAVID KIEWIT
`5901 THIRD ST SOUTH
`ST PETERSBURG, FL 33705 (US)
`
`Assignee: Harald Philipp, Hamble, Southampton
`(GB)
`
`Appl. No.:
`
`11/428,670
`
`Filed:
`
`Jul. 5, 2006
`
`Related US. Application Data
`
`(60)
`
`Provisional application No. 60/697,613, ?led on Jul.
`8, 2005.
`
`Publication Classi?cation
`
`(51)
`
`Int. Cl.
`G09G 5/00
`
`(2006.01)
`
`Exhibit 2018 - Page 01 of 17
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`

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`Patent Application Publication
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`US 2007/0008299 A1
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`Exhi
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`Patent Application Publication
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`Jan. 11, 2007 Sheet 2 0f 8
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`US 2007/0008299 A1
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`US 2007/0008299 A1
`
`Jan. 11, 2007
`
`TWO-DIMENSIONAL POSITION SENSOR
`
`BACKGROUND OF THE INVENTION
`
`[0001] The invention relates to a capacitive position sen
`sor for determining the position of an object Within a
`tWo-dimensional sensing area.
`
`[0002] The use of tWo-dimensional touch-sensitive posi
`tion sensors is becoming more common. Examples include
`the use of position sensors in laptop computers in place of
`mouse pointing devices, as control panels for receiving user
`inputs to control an appliance, or particularly as a glass
`touchscreen apparatus having an X-Y coordinate output.
`Some applications require a clear sensing layer so that a
`display can be vieWed beneath the screen, While others only
`require an opaque touch surface, for example for a keypanel
`on a kitchen appliance or a PC peripheral.
`
`[0003] Touch-sensitive position sensors are frequently
`preferred to mechanical devices because they provide for a
`more robust interface and are often considered to be more
`aesthetically pleasing. Furthermore, because touch-sensitive
`position sensors require no moving parts to be accessible to
`a user, they are less prone to Wear than their mechanical
`counterparts and can be provided Within a sealed outer
`surface. This makes their use Where there is a danger of dirt
`or ?uids entering a device being controlled particularly
`attractive.
`
`[0004] There exists a large body of art involving 2D
`touchpanels and screens. They can be generally divided into
`tWo classi?cations: those that report an X-Y coordinate of a
`more or less continuous nature (‘XY’ type), and those that
`have a discrete sensing surface (‘discrete’ type) having
`prede?ned key areas that are ?xed by physical geometry.
`The XY type ?nd dominant use over LCD or other display
`types While the latter ?nd use in ?xed function key panels.
`There are exceptions to this, for example touchpad surfaces
`on laptops report XY position but are opaque. XY types
`invariably involve a sensing surface on the user-side or ‘?rst
`surface’ of the touch area. For example, both continuous
`resistive and capacitive touch screens involve a sensing
`layer that must be either physically depressed by the user or
`touched almost directly, or at most through a thin layer of
`insulation (as in mouse touchpads). These types require that
`the product have a beZel opening to alloW direct or near
`direct contact by the user With the sensing layer. A signi?
`cant disadvantage of these types is that there has to be an
`opening in the panel, Which requires sealing against mois
`ture and dirt and hence is expensive to mount. Furthermore
`the sensing layer is directly exposed to abuse and can be
`easily damaged by sharp objects or abrasion. While robust
`capacitive types are knoWn Which have buried Wires inside
`a glass layer (eg US. Pat. No. 5,844,506), these still require
`a beZel opening in a panel Which must be sealed, and require
`tWo sensing layers as a matrix due to the need to cross X and
`Y conductors. Furthermore these screens are very expensive
`to produce and in fact cannot be produced on a mass scale;
`additionally the sensing circuitry is knoWn to be complex
`and expensive.
`[0005] In the ?eld of discrete touch buttons, it has been
`knoWn for some time that capacitive keys can be placed
`behind a solid surface having no requirement for a beZel
`opening. HoWever these types only provide for limited
`resolution, as prede?ned by the location of discrete electrode
`
`shapes. An example of this can be found in US. Pat. No.
`4,954,823, FIGS. 4 and 6. While it is Well knoWn that these
`electrodes can be made of a single layer of clear conductor
`such as Indium Tin Oxide (‘ITO’) to alloW placement over
`a beZel-less display, for example by the application of the
`layer as a ?lm on the back of a subsection of a panel,
`nevertheless the technology is limited to discrete touch areas
`based on the number, siZe, and placement of discrete elec
`trodes.
`
`[0006] FIG. 1 schematically shoWs in plan vieW a touch
`pad 2 of the type described in US. Pat. No. 4,954,823, but
`laid out in an orthogonal array. The touch pad 2 comprises
`a grid of discrete electrodes 4 mounted on an insulating
`substrate 6. Each electrode is connected to a channel of
`capacitance measurement circuitry in a controller 8. US.
`Pat. No. 5,463,388 describes this geometry in passing in
`conjunction With its FIG. 1, to shoW hoW such an array can
`be used to determine a position of an object proximate the
`sensing layer via a method of determining a centroid of the
`signals from each pad. HoWever US. Pat. No. 5,463,388
`fails to shoW hoW to implement such a design and describes
`instead a matrix of conductors along With a centroidal
`calculation of continuous X-Y position. In fact it is not
`practical to have so many sensing channels as one per sense
`pad, and a matrix arrangement is much more ef?cient as
`described beloW.
`
`[0007] FIG. 2 schematically shoWs a position sensor 12
`based on a matrix of conductors as described in US. Pat. No.
`5,463,388. The position sensor 12 comprises a number of
`vertically aligned strip electrodes (columns) 14 mounted on
`an upper surface of an insulating substrate 16 and a number
`of horizontally aligned strip electrodes (roWs) 15 mounted
`on an opposing loWer surface of the insulating substrate.
`Each vertical strip electrode is connected to a channel of
`capacitance measurement circuitry in a controller 18. Thus,
`this type of position sensor alloWs an X-Y coordinate output
`of a continuous nature by means of calculation of a centroid
`of capacitance among the roWs and columns rather than
`among discrete pads. HoWever this type requires tWo sens
`ing layers so that the matrix traces can be routed, and does
`not alloW the use of optically clear materials.
`
`[0008] The ideal touch surface Would eliminate the need
`for a beZel opening (or at least, make it optional), have an
`inexpensive sensing surface that is applied to the rear of the
`panel surface that can project through a reasonable thickness
`of panel material (eg up to 4 mm of glass or plastic),
`optionally require only one sensing layer With no crossovers
`in the sensing region, be usable With clear sensing layers
`such as ITO, have an XY type of output, and have a compact,
`inexpensive driver circuit. This set of ideal goals has not
`been achieved With any knoWn prior art.
`
`SUMMARY OF THE INVENTION
`
`[0009] According to a ?rst aspect of the invention there is
`provided a capacitive position sensor for determining the
`position of an object in a sensing area, the sensor comprising
`a substrate having a surface With an arrangement of elec
`trodes mounted thereon, Wherein the electrodes de?ne an
`array of sensing cells arranged in columns and roWs to form
`the sensing area, each sensing cell including a column
`sensing electrode and a roW sensing electrode, the column
`sensing electrodes of sensing cells in the same column being
`
`Exhibit 2018 - Page 10 of 17
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`US 2007/0008299 A1
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`Jan. 11, 2007
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`electrically coupled together and the roW sensing electrodes
`of sensing cells in the same roW being electrically coupled
`together, Wherein roW sensing electrodes of sensing cells at
`opposing ends of at least one of the roWs are electrically
`coupled to one another by respective roW Wrap-around
`connections made outside of the sensing area.
`
`[0010] Thus a position sensor having electrodes on only a
`single layer of a substrate can be provided. Furthermore,
`because the position sensor employs an intersecting array of
`columns and roWs of sensing electrodes (i.e. a matrix), feWer
`measurement channels are required than With sensors based
`on an array of discrete electrodes.
`
`[0011] Because the position sensor is based on sensing
`electrodes on only a single surface, it can be cheaper to
`manufacture than knoWn double-sided position sensors. This
`also means the sensing electrodes can be deposited directly
`onto a surface for Which the opposing surface is inaccessible
`(eg a display screen). The sensing electrodes can also be
`deposited on an inside surface of a device housing, thus
`removing the need for any protective covering that might be
`required if electrodes Were also required to be on the outer
`surface.
`
`[0012] The electrical roW Wrap-around connections may
`comprise a conductive trace mounted on the substrate. This
`alloWs the connection outside of the sensing area to be made
`in the same processing step as the sensing electrodes Within
`it. Alternatively, the roW Wrap-around connections may be
`made by a free Wire appropriately connected to the respec
`tive roW sensing electrodes.
`
`[0013] The column sensing electrodes of a column of
`sensing cells at an edge of the sensing area may be electri
`cally coupled to one another by column Wrap-around con
`nections made outside of the sensing area in a similar
`fashion.
`
`[0014] The position sensor may further comprise a plu
`rality of capacitance measurement channels connected to
`respective ones of the roWs of roW sensing electrodes and the
`columns of column sensing electrodes, Wherein each mea
`surement channel is operable to generate a signal indicative
`of a capacitance betWeen its associated column or roW of
`sensing electrodes and a system ground.
`
`[0015] In addition, the position sensor may further com
`prise a processor operable to determine the position of the
`object along the ?rst direction by comparing signals from
`the columns of column sensing electrodes and along the
`second direction by comparing signals from the roWs of roW
`sensing electrodes.
`
`[0016] This alloWs the determination of the position of a
`touch to be made using otherWise conventional circuitry
`connected to the sensing elements.
`
`[0017] The capacitance measurement channels may com
`prise charge transfer circuitry since this provides a reliable
`and robust Way to measure capacitances of the level that
`might be expected in a typical implementation. HoWever,
`other forms of capacitance measurement circuitry may
`equally be used. In general it is preferential to use a
`capacitive driver circuit that drives all the roWs and column
`connections in a substantially phase-synchronous manner so
`as to prevent the electric ?elds from cross-loading into
`adjacent roWs and columns. This is described also in Us.
`
`Pat. No. 5,463,388, Where all the roWs and column conduc
`tors are driven by a single oscillator.
`[0018] The sensing cells may be arranged into three or
`four columns. This can provide a position sensor With
`sufficient resolution over a typically siZed sensing area for
`most applications.
`[0019] The column and roW sensing electrodes in each
`sensing cell may be interleaved With one another (eg by
`spiraling around one another or being interlaced/inter
`tWined), especially in designs Where the roW and column
`spacing is larger than that of a typical ?nger. This provides
`for a much more uniform blend of signals from the X and Y
`drives in each intersecting location, alloWing better position
`reporting With respect to a ?nger touching the overlying
`surface. This is described also in Us. Pat. No. 5,463,388, for
`example FIG. 2. In layouts Where the roW and column
`spacings are similar to or smaller than a human ?nger it is
`sufficient to use other arrangements of electrode pattern, for
`example an array of diamond shapes as shoWn in FIG. 8 and
`described further beloW.
`[0020] The position sensor may include a transparent
`substrate and transparent electrodes (e. g. formed from
`Indium Tin Oxide (ITO) deposited on the substrate). This
`alloWs it to be placed over a display screen Without obscur
`ing What is displayed beneath. Thus the display screen might
`be con?gured to display “virtual” buttons to a user that may
`be selected by the user placing their ?nger over the appro
`priate part of the display adjacent the position sensor. The
`position of the user’s touch can then be compared With the
`positions of the “virtual” buttons being displayed to deter
`mine Which one has been selected.
`[0021] According to a second aspect of the invention there
`is provided a device comprising a position sensor according
`to the ?rst aspect of the invention. The position sensor may
`be used in many types of device. For example the device
`may be a portable/hand-held device, eg a personal data
`assistant (PDA), a multimedia player, a mobile (cell) phone,
`a re-con?gurable remote controller, or a still camera or video
`camera, for example With the position sensor overlaying a
`display. Alternatively, the position sensor could equally be
`used in larger scale devices such as kitchen appliances,
`kiosks, and the like. Opaque versions can be fashioned for
`use in PC-style trackpads, keypads, and other human inter
`face devices as are Well knoWn in the art.
`[0022] According to a third aspect of the invention there is
`provided a method of constructing a capacitively sensitive
`surface disposed on a substrate Which reports an X-Y
`coordinate position of an object Within an active sensing
`region When the object is adjacent to said surface, compris
`ing the steps of: (a) depositing a single layer of patterned
`conductive material in the active sensing region, the pattern
`comprising roWs and columns of electrodes connected to
`individual ones of capacitive sensing channels, and Wherein
`at least one roW or column is broken into a plurality of
`segments Within the active region; (b) connecting the broken
`segments together With an electrical conductor, Wherein the
`conductor is made to lie outside of the active sensing region;
`(c) connecting the roWs and columns to individual sensing
`channels of a multi-channel capacitive sensor circuit having
`multiple outputs representing amplitudes of capacitance on
`the roWs and columns; and (d) providing a processor oper
`able to process the multiple outputs to determine a coordi
`nate position of the adjacent object as an XY location.
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`Exhibit 2018 - Page 11 of 17
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`US 2007/0008299 A1
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`Jan. 11, 2007
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`[0023] The processor may be operable to compensate for
`position distortion introduced by the physical geometry of
`the patterned conductive material.
`
`[0024] The processor may also be operable to calculate a
`centroid of the signals across roWs and a centroid of the
`signals across columns.
`
`[0025] According to a fourth aspect of the invention there
`is provided a capacitive position sensor for determining the
`position of an object in a sensing area, the sensor comprising
`a substrate having a surface With an arrangement of con
`ductive electrodes mounted thereon, Wherein the electrodes
`de?ne an array of sensing cells arranged in columns and
`roWs to form the sensing area, each sensing cell including a
`column sensing electrode and a roW sensing electrode, the
`column sensing electrodes of sensing cells in the same
`column being electrically coupled together and the roW
`sensing electrodes of sensing cells in the same roW being
`electrically coupled together, Wherein at least one column
`sensing electrode comprises a continuous spine Within the
`sensing area, and the at least one other column is made
`electrically continuous via connections external to the sens
`ing area.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`[0026] 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 draW
`ings in Which:
`
`[0027] FIG. 1 schematically shoWs in plan vieW a knoWn
`tWo-dimensional capacitive position sensor;
`[0028] FIG. 2 schematically shoWs in plan vieW another
`knoWn tWo-dimensional capacitive position sensor;
`[0029] FIG. 3 schematically shoWs in plan vieW a tWo
`dimensional capacitive position sensor according to an
`embodiment of the invention;
`[0030] FIG. 4 schematically shoWs in perspective vieW a
`device including the position sensor of FIG. 3;
`[0031] FIGS. 5A and 5B are graphs schematically shoW
`ing capacitance as function of column number (FIG. 5A) and
`roW number (FIG. 5B) of sensing cells used to determine the
`position of an object adjacent the position sensor of the
`device shoWn in FIG. 4;
`[0032] FIG. 6 schematically shoWs in plan vieW the tWo
`dimensional capacitive position sensor and display screen of
`the device shoWn in FIG. 4;
`[0033] FIGS. 7 and 8 schematically shoW in plan vieW
`tWo-dimensional capacitive position sensors according to
`other embodiments of the invention;
`[0034] FIG. 9 schematically shoWs in plan vieW reported
`positions compared to actual positions for an object adjacent
`a position sensor according to an embodiment of the inven
`tion; and
`[0035] FIG. 10 schematically shoWs in plan vieW a display
`of the outlines of desired key positions compared to the
`outlines of reported key positions for a position sensor
`according to an embodiment of the invention.
`
`DETAILED DESCRIPTION
`[0036] FIG. 3 schematically shoWs in plan vieW a tWo
`dimensional touch-sensitive capacitive position sensor 22
`
`according to an embodiment of the invention. The position
`sensor 22 is operable to determine the position of an object
`along a ?rst (x) and a second (y) direction, the orientation of
`Which are shoWn toWards the top left of the draWing. The
`sensor 22 comprises a substrate 24 having an arrangement of
`sensing electrodes 26 mounted thereon. The sensing elec
`trodes 26 de?ne a sensing area Within Which the position of
`an object (eg a ?nger or stylus) adjacent the sensor may be
`determined. The substrate 24 is of a transparent plastics
`material and the electrodes are formed from a transparent
`?lm of Indium Tin Oxide (ITO) deposited on the substrate
`24 using conventional techniques. Thus the sensing area of
`the sensor is transparent and can be placed over a display
`screen Without obscuring What is displayed behind the
`sensing area. In other examples the position sensor may not
`be intended to be located over a display and may not be
`transparent; in these instances the ITO layer may be replaced
`With a more economical material such as a copper laminate
`PCB, for example.
`
`[0037] The pattern of the sensing electrodes on the sub
`strate 24 is such as to divide the sensing area into an array
`(grid) of sensing cells 28 arranged into roWs and columns.
`(It is noted that the terms “roW” and “column” are used here
`to conveniently distinguish betWeen tWo directions and
`should not be interpreted to imply either a vertical or a
`horiZontal orientation.) By Way of example one of the
`sensing cell 28 is identi?ed by a dotted outline in FIG. 3. In
`this position sensor there are four columns of sensing cells
`aligned With the y-direction and ?ve roWs of sensing cells
`aligned With the x direction (tWenty sensing cells in total).
`The top-most roW of sensing cells for the orientation shoWn
`in FIG. 3 is referred to as roW y1, the next one doWn as roW
`y2, and so on doWn to roW y5. The columns of sensing cells
`are similarly referred to from left to right as columns x1 to
`x4. Thus the sensing cell 28 shoWn With a dotted outline in
`FIG. 3 is at the intersection of roW y1 and column x3.
`
`[0038] Each sensing cell includes a roW sensing electrode
`30 and a column sensing electrode 32. The roW sensing
`electrodes 30 and column sensing electrodes are arranged
`Within each sensing cell 28 to interleave With one another (in
`this case by squared spiraling around one another), but are
`not galvanically connected. Because the roW and column
`sensing electrodes are interleaved (intertwined), an object
`adjacent a given sensing cell can provide a signi?cant
`capacitive coupling to both sensing electrodes irrespective
`of Where in the sensing cell the object is positioned. The
`characteristic scale of interleaving may be on the order of,
`or smaller than, the capacitive footprint of a typical object to
`be detected to provide the best results. The siZe and shape of
`the sensing cell 28 can be comparable to that of the object
`to be detected or larger (Within practical limits).
`
`[0039] The roW sensing electrodes 30 of all sensing cells
`in the same roW are electrically connected together to form
`?ve separate roWs of roW sensing electrodes. Similarly, the
`column sensing electrodes 32 of all sensing cells in the same
`column are electrically connected together to form four
`separate columns of column sensing electrodes.
`
`[0040] The column sensing electrodes in column x2 are
`connected to one another by a connection 51, also referred
`to as a spine, made Within the sensing area by a part of one
`of the electrodes deposited on the substrate and Which runs
`betWeen columns x2 and x3. This connection runs the length
`
`Exhibit 2018 - Page 12 of 17
`
`

`
`US 2007/0008299 A1
`
`Jan. 11, 2007
`
`of the sensing area. Thus a single continuous conductive
`electrode deposited on the substrate 24 provides the column
`sensing electrodes 32 of all of the sensing cells in column X2
`and their interconnections. The column sensing electrodes in
`column X3 are similarly connected to one another by a
`connection 53 made Within the sensing area, again running
`betWeen columns X2 and X3 as a spine. Thus again a single
`continuous conductive electrode deposited in the substrate
`24 provides the column sensing electrodes 32 of all of the
`sensing cells in column X3 and their interconnections.
`
`[0041] The roW sensing electrodes 30 in columns X1 and
`X2 of roW y2 are also connected together by a connection
`made Within the sensing area. Thus a single continuous
`conductive electrode 34 deposited on the substrate 24 pro
`vides the roW sensing electrodes of the sensing cells in
`columns X1 and X2 of roW y2 and their interconnection. The
`roW sensing electrodes in columns X3 and X4 of roW y2 are
`similarly connected together by a connection made Within
`the sensing area so that a single continuous electrode 36
`again provides these roW sensing electrodes and their inter
`connection. HoWever, because of the on-substrate connec
`tions (spines) running betWeen columns X2 and X3 to con
`nect betWeen their respective column sensing electrodes, the
`roW sensing electrodes in columns X1 and X2 of roW y2
`cannot be connected to the roW sensing electrodes in col
`umns X3 and X4 of roW y2 by a connection made on the
`surface of the substrate. Thus a connection 38 betWeen the
`roW sensing electrodes at opposing ends of this roW (i.e. in
`columns X1 and X4) is provided outside of the sensing area.
`The connection 38 runs around the outside of the sensing
`area to connect the electrode 34 providing the roW sensing
`electrodes in columns X1 and X2 of roW y2 With the electrode
`36 providing the roW sensing electrodes in columns X3 and
`X4 of roW y2. Thus all roW sensing electrodes in this roW are
`electrically connected together. Similar Wrap-around con
`nections outside of the sensing area are made to ensure the
`respective roW sensing electrodes of the other roWs are
`connected together. It is noted that although one is shoWn in
`FIG. 3, a connection outside of the sensing area betWeen the
`roW sensing electrodes at opposing ends of roW y1 is not
`required because the spines connecting betWeen the column
`sensing electrodes of columns X2 and X3 need not eXtend to
`the very edge of the sensing area and a connection running
`along the top edge of the sensing area could be used to
`connect betWeen the roW sensing electrodes in roW y1 (not
`shoWn).
`[0042] Each column sensing electrode in column X1 is
`formed from a separate electrode on the substrate. These
`separate electrodes are connected together by connections
`40 made eXtemal to (i.e. outside of) the sensing area. The
`column sensing electrodes in column X4 are connected
`together by connections 41 in a similar manner to those of
`column X1. In this fashion the outer tWo columns can be
`discontinuous Within the sensing area to alloW access by roW
`electrodes into cells, yet the columns are nevertheless made
`Whole.
`
`[0043] In this eXample the various connections made
`outside of the sensing area betWeen the roW sensing elec
`trodes in sensing cells at opposing ends of the respective
`roWs and the column sensing electrodes in the columns at the
`periphery of the sensing area are formed from free Wires
`attached to the electrodes of the sensing area as appropriate
`using conventional techniques. Because the connections are
`
`established by free Wires, no dif?culties arise from the need
`for the connections made outside of the sensing area to cross
`one another in places. In an alternative design the connec
`tions made outside of the sensing area may be provided by
`conductive traces on the substrate similar to the electrodes
`forming the sensing area. This can be bene?cial because the
`electrodes forming the sensing area and the electrical traces
`making the connections outside of the sensing area can be
`fabricated in single processing step. Conventional electrical
`jumpers can be used at the locations Where connections
`outside of the sensing area cross one another. In yet another
`alternative and more preferable design, the Wiring is accom
`plished by a combination of conductive traces on the sub
`strate similar to the electrodes forming the sensing area
`connecting some attachment nodes, plus a dielectric insula
`tor deposited on top of these conductors, plus conductive ink
`(e.g. silver ink) patterned on top of the dielectric insulator to
`connect together all remaining nodes needing to be joined.
`This produces a loW cost, thin planar surface Which requires
`only Well-knoWn processing steps, With no need for discrete
`jumpers.
`
`[0044] It Will be appreciated that the numbers of roWs and
`columns do not need to be 5 and 4 respectively as shoWn in
`FIG. 3; other numbers of roWs and columns may be used to
`suit different geometries. Also, While the roWs and columns
`are shoWn to be of the same basic dimension giving rise to
`square cells 28, the roWs and columns may be of non
`matching or even non-uniform dimensions giving rise to
`rectangular cells 28, or possibly other shapes such as trap
`eZoids. Furthermore, in cases Where the regions of the cells
`28 are interleaved, they do not require angular patterns of
`interleaving as shoWn; the interleavings can be circular,
`spiral, or other shapes to accomplish the same general e?fect.
`
`[0045] The position sensor 22 further comprises a series of
`capacitance measurement channels 42 coupled to re