a2) United States Patent
`US 7,030,860 B1
`(10) Patent No.:
`Hsu et al.
`(45) Date of Patent:
`Apr.18, 2006
`
`
`US007030860B1
`
`(54) FLEXIBLE TRANSPARENT TOUCH
`SENSING SYSTEM FOR ELECTRONIC
`DEVICES
`
`7B
`(75)
`
`.
`.
`Inventors: Andrew C. Hsu, Belmont, CA (US);
`ShawnP. Day, San Jose, CA (US);
`Richard Schediwy, Union City, CA
`tus David Gillespie, Los Gatos, CA
`
`(*) Notice:
`
`5,305,017 A
`5,381,160 A
`5,386,219 A *
`5,457,289 A
`5,543,588 A
`5'550.504 A
`5,844,506 A
`5,880,411 A
`5,909,211 A *
`
`5,942,733 A
`5,952,998 A *
`6,016,140 A *
`6,137,427 A
`
`4/1994 Gerpheide ....... eee 345/174
`1/1995 Landmeier
`............ 345/174
`1/1995 Greanias et al.
`10/1995 Huang et al. oe. 178/20
`8/1996 Bisset et al.
`9/1996 Ttsumi et al.
`12/1998 Binstead ........ssssueeee 341/34
`3/1999. Gillespieet al.
`6/1999 Combs etal.
`.....
`345/172
`
`
`8/1999 Allen et al. oe 179/1
`y
`9/1999 Clancy etal.
`.....
`... 345/173
`1/2000 Blouin etal. ......
`. 345/178
`(73) Assignee: Synaptics Incorporated, San Jose, CA
`10/2000 Binstead «0.0.0... ee 341/33
`(US)
`(Continued)
`Subject to any disclaimer, the term ofthis
`FOREIGN PATENT DOCUMENTS
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`EP 0185671 Bl=12/1991
`
`
`
`(21) Appl. No.: 09/415,481
`
`(22)
`
`Filed:
`
`Oct. 8, 1999
`
`(51)
`
`(Continued)
`
`Primary Examiner—Amr A. Awad
`Assistant Examiner—Abbas Abdulselam
`(74) Attorney, Agent, or Firm—Ingrassia Fisher & Lorenz
`PC
`
`Int. Cl.
`(2006.01)
`G09G 5/08
`(52) US. Ch woe 345/173; 345/179; 178/18.06
`ABSTRACT
`(58) Field of Classification Search .............. 345/173, ©)
`1enedfa3aOL}nSgon;gos
`A transparent, capacitive sensing system particularly well
`178/18 (6: 341/33 34. 300/211. 463/37.
`suited for input to electronic devices is described. The
`_
`a
`73/180l
`sensing system can be used to emulate physical buttons or
`lication
`file
`f
`\
`b hi
`:
`slider switches that are either displayed on an active display
`file
`tor complete search
`history.
`device or printed on an underlying surface. The capacitive
`ee application
`References Cited
`sensor can further be used as an input device for a graphical
`user interface, especially if overlaid on top of an active
`display device like an LCD screen to sense finger position
`(X/Y position) and contact area (Z) over the display. In
`addition, the sensor can be made with flexible material for
`touch sensing on a three-dimensional surface. Because the
`sensor is substantially transparent, the underlying surface
`can be viewed through the sensor. This allows the underly-
`ing area to be used for alternative applications that may not
`necessarily be related to the sensing system. Examples
`:
`os
`sys
`:
`:
`includeadvertising: an adiitionaluser interlace spy: or
`4Pparatus such
`as a camera or a
`biometric security device.
`
`s
`
`(56)
`
`U.S. PATENT DOCUMENTS
`3,757,322 A
`9/1973 Barkan et al.
`.......... 340/365 C
`4,484,038 A
`11/1984 Dorman et al.
`............. 200/5 A
`4,686,332 A
`8/1987 Greanias et al.
`..........0... 178/19
`
`3/1988 Evans oo...
`wee 340/365 C
`4,733,222 A
`
`2/1989 EVANS .eeeseeseeeeeeeeseeees 178/19
`4,806,709 A .
`
`.i900 fackson ve so,aU
`oatnia A
`amoto et al...
`945,
`
`9/1990 Binstead ......sssseessssseees 341/26
`4,954,823 A
`6/1991 MULOi veeeeeececceseesee 235/462
`5,021,640 A *
`
`
`.....
`... 345/97
`5,122,787 A *
`6/1992 Fujita et al.
`.............. 178/19
`5,149,919 A *
`9/1992 Greaniaset al.
`
`30 Claims, 5 Drawing Sheets
`
`
`
`PETITIONERS
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`Exhibit 1004, Page 1
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`PETITIONERS
`Exhibit 1004, Page 1
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`US 7,030,860 B1
`
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`FOREIGN PATENT DOCUMENTS
`
`6,163,313 A * 12/2000 Aroyan et al... 345/173
`6,222,528 B1*
`4/2001 Gerpheide etal. .......... 345/173
`6,262,717 B1*
`7/2001 Donohueet al.
`........... 345/156
`
`6,297,811 Bl * 10/2001 Kentetal. ...
`345/173
`6/2002 Fujii et al. oe. 349/12
`6,411,344 BL*
`6,414,671 B1*
`7/2002 Gillespie et al.
`............ 345/157
`..
`... 345/173
`6,504,530 B1*
`1/2003 Wilson et al.
`
`2/2004 Chiu oe 178/18.01
`6,686,546 BI1*
`6,704,068 B1*
`3/2004 Murade .......... eee 349/44
`
`EP
`GB
`GB
`Wo
`wo
`wo
`
`0 754 370 BI
`2 161935 A
`2 223 986 A
`WO 85/04994 Al
`WO 88/05577 Al
`WO 95/27334 Al
`
`10/2002
`1/1986
`4/1990
`11/1985
`T1988
`10/1995
`
`* cited by examiner
`
`PETITIONERS
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`U.S. Patent
`
`Apr.18, 2006
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`Sheet 1 of 5
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`US 7,030,860 B1
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`
`
`Figure 1
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`U.S. Patent
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`Apr.18, 2006
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`Sheet 2 of 5
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`US 7,030,860 B1
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`Finger Presaure
`
`Finger Presence /
`
`Figure 3
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`
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`U.S. Patent
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`Apr.18, 2006
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`Sheet 3 of 5
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`US 7,030,860 B1
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`U.S. Patent
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`Apr.18, 2006
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`Sheet 4 of 5
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`US 7,030,860 B1
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`36>
`624
`70
`co
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`FIG. 5D
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`Apr.18, 2006
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`Sheet 5 of 5
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`U.S. Patent
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`US 7,030,860 B1
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`US 7,030,860 B1
`
`1
`FLEXIBLE TRANSPARENT TOUCH
`SENSING SYSTEM FOR ELECTRONIC
`DEVICES
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`Thepresent invention relates to touch sensing transducers
`and systems. Moreparticularly, the present invention relates
`to flexible and transparent object position recognition
`devices useful in applications such as cursor movement and
`user input for computing devices and other applications.
`2. Description of the Related Field
`Touch sensing technology can be usedto provide a variety
`of input
`to electronic devices, from emulating physical
`buttons or slider switches to more sophisticated recognition
`of patterns or gestures. For example, U.S. Pat. No. 5,880,411
`to Gillespie, which is hereby incorporated in its entirety for
`its teaching of touch sensor technology, discloses a capaci-
`tive sensor trace array object position detector with edge
`motion feature and gesture recognition. U.S. Pat. No. 5,305,
`017 to Gerpheide teaches an object position detector using
`capacitive sensing andis also incorporatedin its entirety by
`reference for its teaching of touch sensor technology.
`Another example of capacitive touchpads is U.S. Pat. No.
`5,543,588 to Bisset.
`However, in many applications it is desirable to display
`the surface underlying the touchpad. For example,
`the
`touchpad can be overlaid on an active display such as a LCD
`or CRT screen to facilitate input to a graphical user interface
`(GUI). Alternatively, it may be desired to have the under-
`lying surface display static information such as a button
`pattern to guide user input or advertising. Neither Gillespie
`nor Bisset disclose or suggest the ability to display a surface
`underlying the touchpad sensor.
`The general strategy employed bytheprior art to provide
`transparent touch sensing technology for portable devices
`utilizes a resistive pad. A typical resistive pad consists of two
`substantially transparent substrates separated by a thin air
`gap, typically about 0.006 inches. One substrate is deform-
`able, such as a polyester film, while the other is typically
`rigid, such as glass or polycarbonate plastic. Both substrates
`are coated with a substantially transparent, conductive coat-
`ing like Indium Tin Oxide on the surface where they face
`one another. On the ITO-coated surfaces, one substrate
`contains conductorsatits left and right edges while the other
`substrate contains conductors at
`its top and bottom. To
`measure position in one axis, a voltage gradientis applied to
`one set of conductors while voltage is measured on the other
`set. When an object deforms the resistive pad so that one
`substrate contacts the other, the point of contact will contain
`a voltage proportional to the distance from the conductor
`where the voltage was applied. To measure position in the
`other axis, the conductors for voltage application and mea-
`surement are switched.
`There are other variations of the previously described 4
`wire resistive pad sensors. One example is a 5-wire design
`which alternately applies an X-axis, than Y-axis voltage
`gradient to the one layer and then uses the second layer
`simply to sense voltage.
`Different prior art techniques deal with the difficulty of
`maintaining a constant air gap between the two ITO layers
`and the stretching of the deformable substrate as it wears.
`For example, substantially transparent dielectric spacer dots,
`usually about 0.010" in diameter, can be arranged in a
`regular, grid-like fashion over one of the ITO surfaces.
`These dots help maintain the air gap to prevent the two ITO
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`2
`layers from accidentally contacting. Further, the dots help
`counteract the decreasing performance of the deformable
`substrate as it wears and stretches. However, the use of these
`spacer dots generally reduces the resolution of the touchpad,
`as not all locations of such a resistive pad will necessarily
`generate a signal when the two substrates come in contact.
`In addition to the resistive pad technologies, other
`examples of prior art include capacitance based technolo-
`gies, stylus based technologies and pressure actuation tech-
`nologies. Prior art capacitive touchpads such as U.S. Pat.
`No. 5,457,289 to Huang and U.S. Pat. Nos. 4,806,709 and
`4,733,222 to Evans suffer from various drawbacks oftheir
`own. For example, Huang requires frontal shielding for its
`capacitive touch sensor system and the Evans ’709 requires
`a uniformly electrically conductive surface. Stylus based
`pads such as U.S. Pat. No. 5,381,160 to Landmeir and U.S.
`Pat. No. 4,945,348 to Ibamoto require an electromagnetic
`tool to provide input. Finally, pressure actuated touchpads
`such as U.S. Pat. No. 4,484,038 to Dorman and U.S. Pat. No.
`3,757,322 to Barkan have moving parts and thus suffer from
`drawbacks similar to the resistive pad technologies.
`
`SUMMARY OF THE INVENTION
`
`The invention is a capacitive sensor system comprising a
`sensortrace and a processor configured to detect capacitance
`changes in the sensor trace to determine proximity of a
`conductive object. Preferably, the sensortrace is a part of a
`first plurality of sensor traces oriented in a first direction and
`the processor detects capacitance changes in the sensor
`traces to determine proximity and positioning of the finger
`in the first dimension. More preferably, the system further
`comprises a second plurality of sensor traces oriented in a
`second dimension, wherein the processor is further config-
`ured to detect capacitance changes in the first plurality of
`sensor traces and the second plurality of sensor traces to
`determine proximity and positioning of the conductive
`object along the first and second dimensions. The preferred
`conductive object for this invention is a humanfinger, but a
`conductive stylus or other suitable device can be used as
`well.
`To maximize transparency, the sensor system should have
`a uniform density of sensor traces. Thus, preferred configu-
`rations minimize the overlap of the first plurality and the
`second plurality of sensor traces. For example, each sensor
`trace may be configured as a series of diamond shapes
`aligned along a commonaxis. Accordingly, each plurality of
`sensor traces thus creates a pattern of diamond shaped open
`spaces. By positioningthefirst plurality of sensor traces over
`the secondplurality so that the diamond shapedsensortraces
`fall over the diamond shaped open spaces, the amount of
`overlap between the each plurality of sensor traces is mini-
`mized. Transparency is also maximized by utilizing mate-
`rials having similar indices of refraction.
`A primary object of this invention is a positioning system
`that uses a low-cost, highly integrated, low power, capaci-
`tive transparent sensor. This invention is suitable for many
`handheld electronic applications such as, but not limited to,
`cell phones, pagers, personal digital assistants, remote con-
`trols, and computers. Non-handheld devices that require a
`positioning system with a thin transparent sensor are also
`appropriate for this invention. Preferably, the sensor system
`is equipped with a processor capable of recognizing gestures
`such as tapping or draggingto increase the flexibility of user
`input.
`The current invention described offers a numberof advan-
`
`tages overresistive pads and the otherprior art technologies.
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`US 7,030,860 B1
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`3
`First, this art is rugged. Its performance will not degrade
`over time andis not subject to mechanical wearandstress,
`being completely solid state and having no moving parts.
`Because this art does not rely on deforming a substrate, the
`sensor can be activated with no actuation force. Second, the
`resolution of sensing is determined by the density of sensor
`traces and the precision of the A/D converters in the pro-
`cessor, not the physical properties of the materials as in
`resistive pads. Thus, very high positioning accuracy can be
`achieved. Because the current invention does not require an
`air gap to be maintained between the sensing layers, posi-
`tioning performanceis hardly affected by mechanical dam-
`age or environmental conditions
`such as temperature,
`humidity or power supply voltage. Consequently, the posi-
`tioning capabilities of this art require little to no user
`calibration. Furthermore, the lack of an air gap, with an
`index of refraction much different than the substrate layers,
`allows this art to achieve greater transparency. Finally, the
`ability to use flexible substrate material to build the sensor
`facilitates the integration ofthis art onto devices that require
`a touch-sensing system on a curved,
`three-dimensional
`surface. Alternatively, the sensor array itself can be directly
`appliedto a rigid, curved three-dimensional surface without
`the requirement of a flexible substrate.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shows a schematic representation of a proximity
`transparent capacitive sensing system of the present inven-
`tion.
`FIG. 2 showsa cross sectional view of the embodiment of
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`the proximity and one-dimensional sensor transducer shown
`in FIG.1.
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`35
`
`FIG. 3 shows a schematic representation of a one-dimen-
`sional transparent capacitive sensing system of the present
`invention.
`
`FIG. 4 shows a schematic representation of a two-dimen-
`sional transparent capacitive sensing system of the present
`invention.
`
`FIG. 5A is a top view of the X sensor array in the
`embodiment shown in FIG.4.
`
`FIG. 5B is a top view of the Y sensor array in the
`embodiment shown in FIG.4.
`
`FIG. 5C is a top view of the combined X and Y sensor
`arrays in the embodiment shown in FIG.4.
`FIG. 5D is a cross-sectional view of a two dimensional
`sensor.
`
`FIG. 6 is a cross sectional view of a two-dimensional
`sensor transducer embodiment of the invention with a trans-
`
`parent ground plane to shield X and Y trace arrays from
`electrical noise that might arise beneath the sensor.
`FIG. 7 is a cross sectional view of an alternate embodi-
`mentof the two-dimensional sensor transducer of the inven-
`tion.
`FIG. 8 is a cross sectional view of a two-dimensional
`
`transparent sensor transducer embodiment of the invention
`that allows use of a conductive stylus in additional to finger
`for input.
`FIG. 9 is a cross sectional view of a two-dimensional
`
`sensor transparent transducer embodiment of the invention
`that allows use of any general stylus in addition to finger for
`input.
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`4
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`FIG. 1 is a schematic representation of a preferred
`embodimentof the invention, comprising a O-dimensional,
`capacitive proximity sensing system 2. System 2 accurately
`determines the proximity and contactof finger 4 or any other
`conductive object
`to the sensor 6. Capacitance changes
`induced by finger 4 on the sensor trace in the sensor 6 are
`digitized by the input processing block 8. The digitized
`values of capacitance valuesare processed by arithmetic unit
`10 and then decoded by gesture unit 12 to determine if a
`finger was present. Gesture unit 12 also processes input
`signals to determine the difference between constant finger
`contact and a finger tap. Blocks 8-12 may also incorporate
`methods to suppress electrical noise that may be sensed by
`sensor 6. Suitable means of implementing this sensor
`include the technologies described in U.S. Pat. Nos. 5,880,
`411 and 5,305,017, which were incorporatedin their entirety
`by reference thereto above for these teachings. Other means
`of capacitive sensing technology knownto those of skill in
`the art are also suitable.
`The sensor trace in sensor 6 must be designed so that the
`trace provides adequate capacitive coupling to the finger. In
`the preferred embodiment, the sensor trace is a thin line of
`conductor that is drawn to the location where the finger is
`designed to contact. At this preferred contact area, the trace
`widens to a square or a circle approximately the dimensions
`of a typical fingerprint. This ensures that adequate capacitive
`coupling will occur between the sensor and the finger.
`Non-visible portions of the sensor can optionally be drawn
`with an opaque conductor with better handling properties
`and lower resistance. Examples of an opaque conductor
`include, but are not limited to, silver ink and conductive
`carbon ink.
`
`FIG.2 is a cross sectional view of the preferred embodi-
`ment of the capacitive sensor 6 (and also one-dimensional
`capacitive sensor 20 described below). A top transparent and
`electrically insulating substrate 52 is adhered with an opti-
`cally transparent and electrically insulating adhesive 54 to
`another transparent, electrically insulating substrate 58 that
`is coated with a transparent conductor 56. Typically, the
`substantially transparent conductor 56 is deposited onto the
`substrate 58 either by a sputtering process or by a printing
`method. The pattern of the transparent conductor trace 56
`can be done by a photoresist and acid-etch process. Alter-
`natively, conductor 56 maybeselectively coated, either by
`sputtering or printing, onto a negative pattern overlaying the
`substrate 58. Then, removing the negative pattern leaves the
`appropriate transparent conductor trace pattern. Because
`sensor 6 only detects contact and proximity, only one sensor
`trace and one conductor layer is needed.
`Examples of transparent, electrically insulating substrates
`52 and 58 include, but are in no way limited to, polyester
`film, glass, and polycarbonate plastic. One example of a
`transparent, electrically insulating adhesive is 3M #8142.
`Examples of substantially transparent conductors include,
`but are not limited to, Indium Tin Oxide (ITO), transparent
`conductive plastic, and silver, gold, aluminum alloys. Those
`skilled in the art will recognize that no material is com-
`pletely transparent. To improve transparency of the sensor a
`number of techniques can be utilized. First, substrates 52
`and 58 and adhesive 54 can be chosento have similar indices
`
`of refraction. This improves transparency by minimizing the
`distorting effects of light traveling through materials of
`different refraction indices. Second, employing the sensing
`art described U.S. Pat. No. 5,880,411 allows the use of high
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`US 7,030,860 B1
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`5
`impedanceoutput drivers. Hence, the resistivity of transpar-
`ent conductor layer 56 can be relatively high andstill be
`usable with such a sensing system. A highresistivity such as,
`but not limited to, 300 (2/square increases transparency of
`the substantially transparent conductor layer 56.
`Layer 60 showsthe location of a substrate that would be
`viewable through transparent layers 52-58. Examples of
`such a substrate include, but are not limited to, an opaque
`substrate, or a graphical display device such as, but not
`limited to a Liquid Crystal Display (LCD) or Cathode Ray
`Tube (CRT), artwork, or additional electronics such a fin-
`gerprint recognizer. In some embodiments, layer 60 may be
`omitted altogether. Alternatively, substrate 58 can be omitted
`and transparent conductor 56 can be patterned directly on
`layer 60.
`In yet other alternative embodiments, layers 52-58 can be
`reversed without loss of functionality. Furthermore, adhe-
`sive 54 can be eliminated so long as substrate 52 is electri-
`cally insulating and self-adhering to conductor 56. One
`example of a self-adhering, transparent, electrically insulat-
`ing substrate is transparent-coat paint.
`FIG. 3 shows a schematic representation of a one-dimen-
`sional position sensing system 16. Such a system can detect
`not just finger contact (like proximity sensing system 2), but
`also the location of a finger 4 or other conductive object
`along thedirection of the sensortrace array. In FIG. 3, sensor
`20 containsa plurality of traces oriented along one direction,
`such as the Y axis, allowing sensing system 16 to determine
`the position of finger 4 along that direction. Finger location
`is computed by measuring the capacitance of the traces and
`then computing finger position based on the increase in
`capacitance in traces coveredor near the finger. Specifically,
`Y input processing block 22 measures trace capacitance
`simultaneously in all sensor traces, and digitizes the analog
`capacitance values. These values are then converted to
`position and pressure information in arithmetic block 24.
`Next, position and pressure data are fed into a motion block
`26 and gesture block 28. Motion block 26 computes finger
`motion along the trace array axis based on storing a suc-
`cessive history of finger position values. Gesture block 28
`determines if a finger is actually in contact with sensor 20
`and whether the finger presence over a short period of time
`is considered a “tap”. If a tap gesture is registered,
`the
`gesture unit suppresses the output of the motion unit. Blocks
`22-28 also incorporate methods to suppress electrical noise
`that may be sensed by sensor 20. Suitable algorithms and
`meansfor implementingthis sensor include the technologies
`described in U.S. Pat. Nos. 5,880,411 and 5,305,017, incor-
`porated in their entirety by reference thereto as described
`above. Those skilled in the art will recognize that such
`algorithmsare onlyillustrative and in no waylimiting of the
`capacitive sensing technology that
`is possible with this
`sensor.
`
`The one-dimensionalsensor 20 is comprisedof a plurality
`of sensor traces equally spaced along a given axis. To
`achieve adequate positional resolution, spacing of each
`sensortrace is typically designed so that a finger 4 covers at
`least two traces at any given location in the sensing area to
`allow interpolation between the traces. A higher trace den-
`sity or higher precision A/D converters improves the reso-
`lution to which sensing system 16 can compute finger
`position. To maximize capacitive coupling between a trace
`and a finger, a trace is typically made as wide as possible (for
`example, slightly less than a trace spacing) without touching
`neighboring traces. As described above with respect to the
`proximity sensing system 2, non-visible portions of the
`sensor can optionally be drawn with an opaque conductor.
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`A cross-sectional view of one-dimensional position sen-
`sor 20 is shown in FIG. 2, previously described. In the
`preferred, but not limiting embodiment, the substrate 58 is
`uniformly coated with the transparent conductor and then
`the trace array is patterned using a photoresist and acid-etch
`process. Alternatively, a negative photoresist pattern can be
`screened on transparent substrate 62 and 68, the transparent
`conductor deposited using a sputtering or screening process
`and then the photoresist pattern removed. As discussed
`above with respect to the proximity sensing system 2, the
`stack-up of one-dimensional position sensor 20 comprising
`layers 52-60 can be reversed and a self-adhering, insulative
`substrate 52 can obviate the need for adhesive 54.
`FIG.4 is a schematic representation of a two-dimensional
`position sensing system 32. Such a system can determine
`finger presence as finger position along two direction axes.
`Finger 4 capacitively couples to sensor traces in sensor 36.
`X input processing block 38 and Y input processing block 40
`measure capacitance values of sensor traces in the X and Y
`trace arrays and digitize the capacitance values. Arithmetic
`unit 42 computes position and pressure coordinates based on
`the digitized capacitance values. Next position and pressure
`coordinates are fed into motion unit 44 and gesture unit 46.
`Motion unit 44 computes relative movement of the finger
`comparedto the previous position ofthe finger. Gesture unit
`46 determines the finger presence over time and whetherit
`constitutes a gesture such as a tap. If gesture unit 46
`recognizes a particular gesture, it will suppress the output of
`the motion unit 44. Blocks 38-46 also incorporate methods
`to suppress electrical noise that may be sensed by sensor 36.
`Suitable algorithms and means for implementing this sensor
`include the technologies described in U.S. Pat. Nos. 5,880,
`411 and 5,305,017, incorporated in their entirety by refer-
`ence thereto as described above. Thoseskilled in the art will
`recognize that such algorithmsare only illustrative and in no
`way limiting of the capacitive sensing technology that is
`possible with this sensor.
`FIG. 5A showsthe preferred embodimentforthe array of
`sensor traces used to compute position in the X-axis in
`sensor 36. Each trace 64 is a transparent conductor, equally
`spaced on a transparent, electrically insulating substrate 62.
`Each diamond66 increases the trace area and also leaves a
`
`pattern of diamond-shapedregions containing no conductive
`material. FIG. 5B is the corresponding preferred embodi-
`mentfor the array of sensor traces used to compute position
`in the Y-axis for sensor 36. Each trace 70 is also a transparent
`conductor, equally spaced on transparent, electrically insu-
`lating substrate 68. Diamonds such as diamond 72 increase
`trace area and leave a diamond-shaped region where there is
`no conductive material.
`
`The actual number of sensor arrays and the presence of
`two axes of sensors will depend on the positioning area and
`resolution requirements of a particular device. To achieve
`adequate positional resolution, spacing of each sensor trace
`is typically designed so that a finger 4 covers at least two
`traces in each axis at any given location in the sensing area.
`A higher trace density or more precise A/D converters
`improvesthe resolution that sensing system 32 can compute
`finger position. In some embodimentsofthe art, fewer X and
`Y traces will suffice to achieve the desired sensing resolu-
`tion. Non-visible portions of the sensor can optionally be
`drawn with an opaque conductor such as, but not limited to,
`silver ink.
`
`In the preferred, but not limiting embodiment, substrates
`62 and 68 are uniformly coated with the transparent con-
`ductor and then patterned using a photoresist and acid-etch
`process. Alternately, a negative photoresist pattern can be
`PETITIONERS
`
`Exhibit 1004, Page 10
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`PETITIONERS
`Exhibit 1004, Page 10
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`

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`US 7,030,860 B1
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`7
`screened on transparent substrate 62 and 68, the transparent
`conductor deposited using a sputtering or screening process
`and then the photoresist pattern removed.
`FIG.5C is a top view of sensor 36 with Y-axis traces from
`substrate 68 on top and X-axis traces from substrate 62 on
`the bottom. X-traces 66 are positioned so that their trace
`diamonds 72 fill diamond spaces between the Y axis traces
`70. For illustrative purposes, Y-axis trace diamonds 72 are
`reduced in size to visually distinguish the diamonds in the
`two different arrays. In the preferred embodiment, these
`diamondsare enlarged to the size of the spaces between X
`traces 66 so that sensor 36 appears to have a single uniform
`layer of transparent conductive material (except for the
`small regions where an X trace 64 overlaps a Y trace 70).
`Filling the entire active area with at
`least one layer of
`transparent conductor is desirable, but not limiting for the
`overall transparency of sensor 36 since transparent conduc-
`tive material such as (but not limited to) Indium Tin Oxide
`(ITO), gold, and silver are not perfectly transparent. Any
`region not covered with at least one layer of conductor in
`sensor 36 may be seen because it will have greater trans-
`missivity compared to a region covered with a conductor.
`FIG. 5D showsa cross sectional view of the preferred
`embodiment of two-dimensional sensor 36. This stack-up
`can be reversed in order without loss of functionality. X-axis
`transparent, electrically insulating substrate 62 is the top
`surface that the finger or conductive object touches. The
`bottom side of the transparent, electrically insulating sub-
`strate 62 is the transparent conductor traces 64. A thin,
`transparent, preferably adhesive, insulator 74 separates X
`conductive traces 64 from Y conductive traces 70. Similar to
`
`X traces, Y conductive traces are coated on transparent,
`electrically insulating substrate 68.
`Examples of transparent substrates 62 and 68, insulator
`74, and conductive layers 64 and 70 have been described for
`FIG. 2 and are equally applicable for the two-dimensional
`sensor. Similarly, the same techniques to improve transpar-
`ency such as, but not limited to, matching indices ofrefrac-
`tion among layers, and using a relatively thin layer of
`transparent conductor, can also be applied to the two-
`dimensional sensor. Similar to FIG.2, layer 60 is an optional
`opaque layer that can be viewed through the transparent
`sensor. In some embodiments,
`layer 60 may be omitted
`altogether. Alternatively, in some embodiments, substrate 68
`can be omitted and transparent conductor 70 can be pat-
`terned directly on layer 60.
`A number of additional alternative embodiments of the
`
`invention are possible. For example,electrical shielding may
`be required to isolate sensor traces from electrical noise that
`arises from electrical circuits that are present below the
`sensor. Onepreferred, but not limiting embodiment is shown
`in FIG. 6 on two-dimensional sensor 36. Layers 62—68 are
`the sameart as described in FIG. 5D. Beneath transparent
`substrate 68, another layer of transparent
`insulator 74
`attaches another layer of transparent conductor 78 and
`substrate 80. Unlike transparent conductor layers 64 and 70,
`transparent conductor 78 is a uniform layer of conductor that
`is connected to an electrical ground. Grounding transparent
`conductor 78 provides sensor 36 with electrical shielding
`from electrical noise sources that might radiate from layer
`60 or below. Examples of materials suitable for transparent
`conductor 78 and substrate 80 have already been described
`in FIG.2.
`
`Addinga transparent ground plane using layers 74-80 can
`also be applied to the contact and one-dimensional sensor
`stack-ups shown in FIG. 2 if such a layer were inserted
`between layers 58 and 60.
`
`40
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`45
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`55
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`8
`In yet another embodiment, FIG. 7 shows a two-dimen-
`sional transparent capacitive sensor 36. Transparent sub-
`strate 84 is adhered using transparent insulator 74 to trans-
`parent conductor
`layer 64. Transparent conductor 64
`contains the X trace pattern as shown in FIG. 5A and is
`coated onto transparent substrate 86. On the other surface of
`transparent substrate 86,
`transparent conductor layer 70
`contains Y trace array shown FIG. 5B. Finally, transparent
`substrate 88 is adhered to transparent conductor 70 with
`transparent insulator 74. This particular embodiment, with
`substrate 86 coated on both sides with transparent conductor
`layers may allow for less error when aligning diamonds in
`the X trace array andthe Y trace array. Because substrate 86
`contains both conductor layers 64 and 70, the alignment of
`trace arrays can occur prior to the etching/deposition of the
`trace arrays with the opaque photoresist pattern, greatly
`simplifying pattern alignment of X and Y traces. Proper
`alignmentof the X and Y trace arraysis critical to the overall
`transparency of two-dimensional sensor 36 because the
`human eye can easily detect any systematic misalignment
`between the trace array patterns.
`Examples of transparent, electrically insulating substrates
`84,86, and 88 have been described in previous embodiments
`of two-dimensional sensor 36 and one-dimensional sensor
`20. Additionally, for electrical shielding, transparent sub-
`strate 88 can be replaced with layers 78 and 80 as shown in
`FIG.6.
`
`This invention may also be adapted for use with a stylus
`in addition to the human finger. One method for doing so is
`to enlarge the contact area for a conductive stylus until its
`contact area is similar to that ofa finger. This has the obvious
`disadvantageof the stylus needing to be both conductive and
`the contact area needing to be large enough to capacitively
`couple to enough sensortraces. To reduce the contact area of
`the conductive input, one method is to increase the trace
`density so that even a fine, pointed conductive sty