Two Dimensional Position Sensor
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`EXHIBIT 1005
`IPR Petition for U.S. Patent No. 8,004,497
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`TITLE OF THE INVENTION
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`TWO-DIMENSIONAL POSITION SENSOR
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`BACKGROUND OF THE INVENTION
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`5
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`The invention relates to a capacitive position sensor for determining the
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`position of an object within a two-dimensional sensing area.
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`The use of two-dimensional touch-sensitive position sensors is becoming more
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`common. Examples include the use of position sensors in laptop computers in place of
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`mouse pointing devices, as control panels for receiving user inputs to control an
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`appliance, or particularly as a glass touchscreen apparatus having an X-Y coordinate
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`output. Some applications require a clear sensing layer so that a display can be viewed
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`beneath the screen, while others only require an opaque touch surface, for example for
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`a keypanel on a kitchen appliance or a PC peripheral.
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`Touch-sensitive position sensors are frequently preferred to mechanical
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`devices because they provide for a more robust interface and are often considered to
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`be more aesthetically pleasing. Furthermore, because touch-sensitive position sensors
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`require no moving parts to be accessible to a user, they are less prone to wear than
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`their mechanical counterparts and can be provided within a sealed outer surface. This
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`makes their use where there is a danger of dirt or fluids entering a device being
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`controlled particularly attractive.
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`There exists a large body of art involving 2D touchpanels and screens. They
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`can be generally divided into two classifications: those that report an X-Y coordinate
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`of a more or less continuous nature ('XY' type), and those that have a discrete sensing
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`surface ('discrete' type) having predefined key areas that are fixed by physical
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`geometry. The XY type find dominant use over LCD or other display types while the
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`latter find use in fixed function key panels. There are exceptions to this, for example
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`touchpad surfaces on laptops report XY position but are opaque. XY types invariably
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`involve a sensing surface on the user-side or 'first surface' of the touch area. For
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`example, both continuous resistive and capacitive touch screens involve a sensing
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`layer that must be either physically depressed by the user or touched almost directly,
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`or at most through a thin layer of insulation {as in mouse touchpads). These types
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`require that the product have a bezel opening to allow direct or near-direct contact by
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`the user with the sensing layer. A significant disadvantage of these types is that there
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`has to be an opening in the panel, which requires sealing against moisture and dirt and
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`5
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`hence is expensive to mount. Furthermore the sensing layer is directly exposed to
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`abuse and can be easily damaged by sharp objects or abrasion. While robust capacitive
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`types are known which have buried wires inside a glass layer {e.g. US 5,844,506 [1]),
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`these still require a bezel opening in a panel which must be sealed, and require two
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`sensing layers as a matrix due to the need to cross X and Y conductors. Furthermore
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`these screens are very expensive to produce and in fact cannot be produced on a mass
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`scale; additionally the sensing circuitry is known to be complex and expensive.
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`In the field of discrete touch buttons, it has been known for some time that
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`capacitive keys can be placed behind a solid surface having no requirement for a bezel
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`opening. However these types only provide for limited resolution, as predefined by the
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`location of discrete electrode shapes. An example of this can be found in US
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`4,954,823 [2], Figures 4 and 6. While it is well known that these electrodes can be
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`made of a single layer of clear conductor such as Indium Tin Oxide ('ITO') to allow
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`placement over a bezel-less display, for example by the application of the layer as a
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`film on the back of a subsection of a panel, nevertheless the technology is limited to
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`discrete touch areas based on the number, size, and placement of discrete electrodes.
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`Figure 1 schematically shows in plan view a touch pad 2 of the type described
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`in US 4,954,823 [2], but laid out in an orthogonal array. The touch pad 2 comprises a
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`grid of discrete electrodes 4 mounted on an insulating substrate 6. Each electrode is
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`connected to a channel of capacitance measurement circuitry in a controller 8. US
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`5,463,388 [3] describes this geometry in passing in conjunction with its Figure 1, to
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`show how such an array can be used to determine a position of an object proximate
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`the sensing layer via a method of determining a centroid of the signals from each pad.
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`However US 5,463,388 fails to show how to implement such a design and describes
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`instead a matrix of conductors along with a centroidal calculation of continuous X-Y
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`position. In fact it is not practical to have so many sensing channels as one per sense
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`pad, and a matrix arrangement is much more efficient as described below.
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`Figure 2 schematically shows a position sensor 12 based on a matrix of
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`conductors as described in US 5,463,388 [3]. The position sensor 12 comprises a
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`number of vertically aligned strip electrodes (columns) 14 mounted on an upper
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`surface of an insulating substrate 16 and a number of horizontally aligned strip
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`5
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`electrodes (rows) 15 mounted on an opposing lower surface of the insulating
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`substrate. Each vertical strip electrode is connected to a channel of capacitance
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`measurement circuitry in a controller 18. Thus, this type of position sensor allows an
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`X-Y coordinate output of a continuous nature by means of calculation of a centroid of
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`capacitance among the rows and columns rather than among discrete pads. However
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`this type requires two sensing layers so that the matrix traces can be routed, and does
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`not allow the use of optically clear materials.
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`The ideal touch surface would eliminate the need for a bezel opening (or at
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`least, make it optional), have an inexpensive sensing surface that is applied to the rear
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`of the panel surface that can project through a reasonable thickness of panel material
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`(e.g. up to 4mm of glass or plastic), optionally require only one sensing layer with no
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`crossovers in the sensing region, be usable with clear sensing layers such as ITO, have
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`an XY type of output, and have a compact, inexpensive driver circuit. This set of ideal
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`goals has not been achieved with any known prior art.
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`SUMMARY OF THE INVENTION
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`According to a first aspect of the invention there is provided a capacitive
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`position sensor for determining the position of an object in a sensing area, the sensor
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`5
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`comprising a substrate having a surface with an arrangement of electrodes mounted
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`thereon, wherein the electrodes define an array of sensing cells arranged in columns
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`and rows to form the sensing area, each sensing cell including a column sensing
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`electrode and a row sensing electrode, the column sensing electrodes of sensing cells
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`in the same column being electrically coupled together and the row sensing electrodes
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`of sensing cells in the same row being electrically coupled together, wherein row
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`sensing electrodes of sensing cells at opposing ends of at least one of the rows are
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`electrically coupled to one another by respective row wrap-around connections made
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`outside of the sensing area.
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`Thus a position sensor having electrodes on only a single layer of a substrate
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`15
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`can be provided. Furthermore, because the position sensor employs an intersecting
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`array of columns and rows of sensing electrodes (i.e. a matrix), fewer measurement
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`channels are required than with sensors based on an array of discrete electrodes.
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`Because the position sensor is based on sensing electrodes on only a single
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`surface, it can be cheaper to manufacture than known double-sided position sensors.
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`20
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`This also means the sensing electrodes can be deposited directly onto a surface for
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`which the opposing surface is inaccessible (e.g. a display screen). The sensing
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`electrodes can also be deposited on an inside surface of a device housing, thus
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`removing the need for any protective covering that might be required if electrodes
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`were also required to be on the outer surface.
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`The electrical row wrap-around connections may comprise a conductive trace
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`mounted on the substrate. This allows the connection outside of the sensing area to be
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`made in the same processing step as the sensing electrodes within it. Alternatively, the
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`row wrap-around connections may be made by a free "'ire appropriately connected to
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`the respective row sensing electrodes.
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`-5-
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`The column sensing electrodes of a column of sensing cells at an edge of the
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`sensing area may be electrically coupled to one another by column wrap-around
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`connections made outside of the sensing area in a similar fashion.
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`The position sensor may further comprising a plurality of capacitance
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`5 measurement channels connected to respective ones of the rows of row sensing
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`electrodes and the columns of column sensing electrodes, wherein each measurement
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`channel is operable to generate a signal indicative of a capacitance between its
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`associated column or row of sensing electrodes and a system ground.
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`In addition, the position sensor may further comprise a processor operable to
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`1 0
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`determine the position of the object along the first direction by comparing signals
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`from the columns of column sensing electrodes and along the second direction by
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`comparing signals from the rows of row sensing electrodes.
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`This allows the determination of the position of a touch to be made using
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`otherwise conventional circuitry connected to the sensing elements.
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`15
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`The capacitance measurement channels may comprise charge transfer circuitry
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`since this provides a reliable and robust way to measure capacitances of the level that
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`might be expected in a typical implementation. However, other forms of capacitance
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`measurement circuitry may equally be used. In general it is preferential to use a
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`capacitive driver circuit that drives all the rows and column connections in a
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`substantially phase-synchronous manner so as to prevent the electric fields from cross(cid:173)
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`loading into adjacent rows and columns. This is described also in US 5,463,388 [3],
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`where all the rows and column conductors are driven by a single oscillator.
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`The sensing cells may be arranged into three or four columns. This can provide
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`a position sensor with sufficient resolution over a typically sized sensing area for most
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`applications.
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`The column and row sensing electrodes in each sensing cell may be
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`interleaved with one another (e.g. by spiraling around one another or being
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`interlaced/intertwined), especially in designs where the row and column spacing is
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`larger than that of a typical finger. This provides for a much more uniform blend of
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`signals from the X and Y drives in each intersecting location, allowing better position
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`reporting with respect to a finger touching the overlying surface. This is described also
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`-6-
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`in US 5,463,388 [3], for example Figure 2. In layouts where the row and column
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`spacings are similar to or smaller than a human finger it is sufficient to use other
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`arrangements of electrode pattern, for example an array of diamond shapes as shown
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`in Figure 8 and described further below.
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`5
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`The position sensor may include a transparent substrate and transparent
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`electrodes (e.g. formed from Indium Tin Oxide (ITO) deposited on the substrate). This
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`allows it to be placed over a display screen without obscuring what is displayed
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`beneath. Thus the display screen might be configured to display "virtual" buttons to a
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`user that may be selected by the user placing their finger over the appropriate part of
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`the display adjacent the position sensor. The position of the user's touch can then be
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`compared with the positions of the "virtual" buttons being displayed to determine
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`which one has been selected.
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`According to a second aspect of the invention there is provided a device
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`comprising a position sensor according to the first aspect of the invention. The
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`position sensor may be used in many types of device. For example the device may be
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`a portable I hand-held device, e.g. a personal data assistant (PDA), a multimedia
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`player, a mobile (cell) phone, a re-configurable remote controller, or a still camera or
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`video camera, for example with
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`the position sensor overlaying a display.
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`Alternatively, the position sensor could equally be used in larger scale devices such as
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`kitchen appliances, kiosks, and the like. Opaque versions can be fashioned for use in
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`PC-style trackpads, keypads, and other human interface devices as are well known in
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`the art.
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`According to a third aspect of the invention there is provided a method of
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`constructing a capacitively sensitive surface disposed on a substrate which reports an
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`25 X-Y coordinate position of an object within an active sensing region when the object
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`is adjacent to said surface, comprising the steps of: (a) depositing a single layer of
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`patterned conductive material in the active sensing region, the pattern comprising
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`rows and columns of electrodes connected to individual ones of capacitive sensing
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`channels, and wherein at least one row or column is broken into a plurality of
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`segments within the active region; (b) connecting the broken segments together with
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`an electrical conductor, wherein the conductor is made to lie outside of the active
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`-7-
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`sensing region; (c) connecting the rows and columns to individual sensing channels of
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`a multi-channel capacitive sensor circuit having multiple outputs representing
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`amplitudes of capacitance on the rows and columns; and (d) providing a processor
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`operable to process the multiple outputs to determine a coordinate position of the
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`5
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`adjacent object as an XY location.
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`The processor may be operable to compensate for position distortion
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`introduced by the physical geometry of the patterned conductive material.
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`The processor may also be operable to calculate a centroid of the signals
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`across rows and a centroid of the signals across columns.
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`According to a fourth aspect of the invention there is provided a capacitive
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`position sensor for determining the position of an object in a sensing area, the sensor
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`comprising a substrate having a surface with an arrangement of conductive electrodes
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`mounted thereon, wherein the electrodes define an array of sensing cells arranged in
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`columns and rows to form the sensing area, each sensing cell including a column
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`15
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`sensing electrode and a row sensing electrode, the column sensing electrodes of
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`sensing cells in the same column being electrically coupled together and the row
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`sensing electrodes of sensing cells in the same row being electrically coupled together,
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`wherein at least one column sensing electrode comprises a continuous spine within the
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`sensing area, and the at least one other column is made electrically continuous via
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`connections external to the sensing area.
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`-8-
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`For a better understanding of the invention and to show how the same may be
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`carried into effect reference is now made by way of example to the accompanying
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`drawings in which:
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`Figure 1 schematically shows in plan view a known two-dimensional
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`capacitive position sensor;
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`Figure 2 schematically shows in plan view another known two-dimensional
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`capacitive position sensor;
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`Figure 3 schematically shows in plan view a two-dimensional capacitive
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`position sensor according to an embodiment of the invention;
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`Figure 4 schematically shows in perspective view a device including the
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`position sensor of Figure 3;
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`Figures 5A and 5B are graphs schematically showing capacitance as function
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`of column number (Figure SA) and row number (Figure 5B) of sensing cells used to
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`determine the position of an object adjacent the position sensor of the device shown in
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`Figure 4;
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`Figure 6 schematically shows in plan view the two-dimensional capacitive
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`position sensor and display screen ofthe device shown in Figure 4;
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`Figures 7 and 8 schematically shows in plan view two-dimensional capacitive
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`position sensors according to other embodiments ofthe invention;
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`Figure 9 schematically shows in plan view reported positions compared to
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`actual positions for an object adjacent a position sensor according to an embodiment
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`ofthe invention; and
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`Figure 10 schematically shows in plan view a display of the outlines of desired
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`key positions compared to the outlines of reported key positions for a position sensor
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`according to an embodiment ofthe invention.
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`-9-
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`DETAILED DESCRIPTION
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`Figure 3 schematically shows in plan view a two-dimensional touch-sensitive
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`capacitive position sensor 22 according to an embodiment of the invention. The
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`5
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`position sensor 22 is operable to determine the position of an object along a first (x)
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`and a second (y) direction, the orientation of which are shown towards the top left of
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`the drawing. The sensor 22 comprises a substrate 24 having an arrangement of sensing
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`electrodes 26 mounted thereon. The sensing electrodes 26 define a sensing area within
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`which the position of an object (e.g. a finger or stylus) adjacent the sensor may be
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`10
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`determined. The substrate 24 is of a transparent plastics material and the electrodes
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`are formed from a transparent film of Indium Tin Oxide (ITO) deposited on the
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`substrate 24 using conventional techniques. Thus the sensing area of the sensor is
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`transparent and can be placed over a display screen without obscuring what is
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`displayed behind the sensing area. In other examples the position sensor may not be
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`intended to be located over a display and may not be transparent; in these instances
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`the ITO layer may be replaced with a more economical material such as a copper
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`laminate PCB, for example.
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`The pattern of the sensing electrodes on the substrate 24 is such as to divide
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`the sensing area into an array (grid) of sensing cells 28 arranged into rows and
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`columns. (It is noted that the terms "row" and "column" are used here to conveniently
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`distinguish between two directions and should not be interpreted to imply either a
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`vertical or a horizontal orientation.) By way of example one of the sensing cell 28 is
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`identified by a dotted outline in Figure 3. In this position sensor there are four
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`columns of sensing cells aligned with the y-direction and five rows of sensing cells
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`aligned with the x direction (twenty sensing cells in total). The top-most row of
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`sensing cells for the orientation shown in Figure 3 is referred to as row yl, the next
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`one down as row y2, and so on down to row y5. The columns of sensing cells are
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`similarly referred to from left to right as columns xl to x4. Thus the sensing cell 28
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`shown with a dotted outline in Figure 3 is at the intersection of row yl and column x3.
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`30
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`Each sensing cell includes a row sensing electrode 30 and a column sensing
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`electrode 32. The row sensing electrodes 30 and column sensing electrodes are
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`-10-
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`arranged within each sensing cell 28 to interleave with one another (in this case by
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`squared spiraling around one another), but are not galvanically connected. Because the
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`row and column sensing electrodes are interleaved (intertwined), an object adjacent a
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`given sensing cell can provide a significant capacitive coupling to both sensing
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`5
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`electrodes irrespective of where in the sensing cell the object is positioned. The
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`characteristic scale of interleaving may be on the order of, or smaller than, the
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`capacitive footprint of a typical object to be detected to provide the best results. The
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`size and shape of the sensing cell 28 can be comparable to that of the object to be
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`detected or larger (within practical limits).
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`10
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`The row sensing electrodes 30 of all sensing cells in the same row are
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`electrically connected together to form five separate rows of row sensing electrodes.
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`Similarly, the column sensing electrodes 32 of all sensing cells in the same column are
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`electrically connected together to form four separate columns of column sensing
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`electrodes.
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`15
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`The column sensing electrodes in column x2 are connected to one another by a
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`connection 51, also referred to as a spine, made within the sensing area by a part of
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`one of the electrodes deposited on the substrate and which runs between columns x2
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`and x3. This connection runs the length ofthe sensing area. Thus a single continuous
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`conductive electrode deposited on the substrate 24 provides the column sensing
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`20
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`electrodes 32 of all of the sensing cells in column x2 and their interconnections. The
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`column sensing electrodes in column x3 are similarly connected to one another by a
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`connection 53 made within the sensing area, again running between columns x2 and
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`x3 as a spine. Thus again a single continuous conductive electrode deposited in the
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`substrate 24 provides the column sensing electrodes 32 of all of the sensing cells in
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`25
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`column x3 and their interconnections.
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`The row sensing electrodes 30 in columns xl and x2 of row y2 are also
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`connected together by a connection made within the sensing area. Thus a single
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`continuous conductive electrode 34 deposited on the substrate 24 provides the row
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`sensing electrodes of the sensing cells in columns xI and x2 of row y2 and their
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`30
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`interconnection. The row sensing electrodes in columns x3 and x4 of row y2 are
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`similarly connected together by a connection made within the sensing area so that a
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`-11-
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`single continuous electrode 36 again provides these row sensing electrodes and their
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`interconnection. However, because of the on-substrate connections (spines) running
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`between columns x2 and x3 to connect between their respective column sensing
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`electrodes, the row sensing electrodes in columns xI and x2 of row y2 cannot be
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`5
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`connected to the row sensing electrodes in columns x3 and x4 of row y2 by a
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`connection made on the surface of the substrate. Thus a connection 38 between the
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`row sensing electrodes at opposing ends of this row (i.e. in columns xi and x4) is
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`provided outside of the sensing area. The connection 38 runs around the outside of the
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`sensing area to connect the electrode 34 providing the row sensing electrodes in
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`10
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`columns xi and x2 of row y2 with the electrode 36 providing the row sensing
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`electrodes in columns x3 and x4 of row y2. Thus all row sensing electrodes in this
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`row are electrically connected together. Similar wrap-around connections outside of
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`the sensing area are made to ensure the respective row sensing electrodes of the other
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`rows are connected together. It is noted that although one is shown in Figure 3, a
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`connection outside of the sensing area between the row sensing electrodes at opposing
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`ends of row y1 is not required because the spines connecting between the column
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`sensing electrodes of columns x2 and x3 need not extend to the very edge of the
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`sensing area and a connection running along the top edge of the sensing area could be
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`used to connect between the row sensing electrodes in row yl (not shown).
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`Each column sensing electrode in column x 1 is formed from a separate
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`electrode on the substrate. These separate electrodes are connected together by
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`connections 40 made external to (i.e. outside of) the sensing area. The column sensing
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`electrodes in column x4 are connected together by connections 41 in a similar manner
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`to those of column xl. In this fashion the outer two columns can be discontinuous
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`25 within the sensing area to allow access by row electrodes into ceJls, yet the columns
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`are nevertheless made whole.
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`In this example the various connections made outside of the sensing area
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`between the row sensing electrodes in sensing cells at opposing ends of the respective
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`rows and the column sensing electrodes in the columns at the periphery of the sensing
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`30
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`area are formed from free wires attached to the electrodes of the sensing area as
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`appropriate using conventional techniques. Because the connections are established by
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`-12-
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`free wires, no difficulties arise from the need for the connections made outside of the
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`sensing area to cross one another in places. In an alternative design the connections
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`made outside of the sensing area may be provided by conductive traces on the
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`substrate similar to the electrodes forming the sensing area. This can be beneficial
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`5
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`because the electrodes forming the sensing area and the electrical traces making the
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`connections outside of the sensing area can be fabricated in single processing step.
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`Conventional electrical jumpers can be used at the locations where connections
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`outside of the sensing area cross one another. In yet another alternative and more
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`preferable design, the wiring is accomplished by a combination of conductive traces
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`I 0
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`on the substrate similar to the electrodes forming the sensing area connecting some
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`attachment nodes, plus a dielectric insulator deposited on top of these conductors, plus
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`conductive ink (e.g. silver ink) patterned on top of the dielectric insulator to connect
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`together all remaining nodes needing to be joined. This produces a low cost, thin
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`planar surface which requires only well-known processing steps, with no need for
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`15
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`discrete jumpers.
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`It will be appreciated that the numbers of rows and columns do not need to be
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`5 and 4 respectively as shown in Fig. 3; other numbers of rows and columns may be
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`used to suit different geometries. Also, while the rows and columns are shown to be of
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`the same basic dimension giving rise to square cells 28, the rows and columns may be
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`20
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`of non-matching or even non-uniform dimensions giving rise to rectangular cells 28,
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`or possibly other shapes such as trapezoids. Furthermore, in cases where the regions
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`of the cells 28 are interleaved, they do not require angular patterns of interleaving as
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`shown; the interleavings can be circular, spiral, or other shapes to accomplish the
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`same general effect.
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`25
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`The position sensor 22 further comprises a series of capacitance measurement
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`channels 42 coupled to respective ones of the rows of row sensing electrodes and the
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`columns of column sensing electrodes. Each measurement channel is operable to
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`generate a signal indicative of a value of capacitance between the associated column
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`or row of sensing electrodes and a system ground. The capacitance measurement
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`30
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`channels 42 are shown in Figure 3 as two separate banks with one bank coupled to the
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`rows of row sensing electrodes (measurement channels labeled yl to y5) and one bank
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`

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`-13-
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`coupled to the columns of column sensing electrodes (measurement channels labeled
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`xl to x4). However, it will be appreciated that in practice all of the measurement
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`channel circuitry will most likely be provided in a single unit such as a programmable
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`or application specific
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`integrated circuit. Furthermore, although nine separate
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`5 measurement channels are shown in Figure 3, the capacitance measurement channels
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`could equally be provided by a single capacitance measurement channel with
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`appropriate multiplexing although this is not a preferred mode of operation. Equally
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`the circuitry ofthe kind described in US 5,463,388 [3] or similar can be used, which
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`while using a scanning multiplexer does drive all the rows and columns with a single
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`I 0
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`oscillator simultaneously in order to propagate a laminar set of sensing fields through
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`the overlying substrate. Preferably, the sensing channels 42 are multiple in-phase
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`charge-transfer sensors ofthe type described in US 5,730,165 [4] or US 6,466,036 [5].
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`Driving multiple ones of such sensing circuits in a phase synchronous manner
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`provides for a desirable laminar field flow.
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`15
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`It is also noted that the substrate provides a valuable function in further mixing
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`the electric fields, so that not only are the fields from X and Y lines better mixed
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`above cells 28, but sensing gradients are produced between adjacent ones of cells 28.
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`This gives . rise to the ability to provide interpolated positions in both X and Y
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`dimensions even though the dimensions of cells 28 are wider than an actuating object.
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`20
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`Thicker panels are noted to give better mixing performance and hence a better ability
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`to interpolate position.
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`The signals indicative of the capacitance values measured by the measurement
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`channels 42 are provided to processing circuitry 44. The processing circuitry is
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`configured to determine the interpolated position of a capacitive load applied to the
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`25
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`sensing area by an object adjacent the position sensor. The interpolated position ofthe
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`capacitive load along the x-direction is determined from the signals from the
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`capacitance measurement channels associated with the columns of column sensing
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`electrodes and the interpolated position of the capacitive load along the y-direction is
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`determined from the signals from the capacitance measurement channels associated
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`30 with the rows of row sensing electrodes. Once the position of the object along the x-
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`

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`-14-
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`and y- directions has been determined, the position is reported to a host controller 46
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`so that it can take appropriate action.
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`Figure 4 schematically shows in perspective view a device 50 including the
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`position sensor 22 shown in Figure 3. The device in this example is a hand-held
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`5 multimedia player comprising a housing 52 containing device control electronics (not
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`shown) and a liquid crystal display screen 54. Various lines oftext can be seen on the
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`display screen, for example, representing a menu of commands for the device. The
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`sensing area of the position sensor overlays the display screen 54 with the electrical
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`connections between the various column and row sensing electrodes made outside of
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`10
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`the sensing area being hidden from view within the housing 52. The electrode layer is
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`completely inside the housing, being underneath the cover plastic, being a film layer
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`that is applied to the interior of the enclosure. This provides for a control surface
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`having no openings and therefore no need for a bezel. The use of a single layer of
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`clear ITO with external node connections provides for high clarity and low cost. A
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`15
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`user can select from the menu of commands displayed on the screen 54 by pointing