a2) United States Patent
`US 6,762,752 B2
`(10) Patent No.:
`Perski etal.
`(45) Date of Patent:
`Jul. 13, 2004
`
`
`US006762752B2
`
`(54) DUAL FUNCTION INPUT DEVICE AND
`METHOD
`
`(75)
`
`Inventors: Haim Perski, Hod Hasharon (IL); Meir
`Morag,Tel Aviv (IL)
`.
`.
`.
`(73) Assignee: N-trig Ltd., Tel-Aviv (IL)
`(*) Notice:
`Subject to any disclaimer, the term ofthis
`patentis extended or adjusted under 35
`US.C. 154(b) by 0 days.
`
`5,402,151 A
`5,510,813 A *
`5,543,589 A *
`5,670,755 A *
`5,777,607 A *
`5,790,106 A *
`6,128,007 A
`6,239,389 BL *
`6,392,636 Bl *
`6,417,846 Bl *
`6,504,530 Bl *
`
`3/1995 Duwaer
`4/1996 Makinwa et al.
`........... 345/173
`8/1996 Buchanaetal. ......... 178/18.03
`
`9/1997 KWOn vececssseseeee 178/18.05
`7/1998 Koolen vceccsecseseeeeeee 345/174
`8/1998 Hirano et al... 345/173
`10/2000 Seybold
`5/2001 Allen et al. ssscsne 178/18.01
`5/2002 Ferrari et al. osc... 345/173
`
`. 345/13
`7/2002 Lee veces
`1/2003 Wilson et al. we... 345/173
`
`(21) Appl. No.: 10/270,373
`
`(22)
`
`(65)
`
`Filed:
`
`Oct. 15, 2002
`
`Prior Publication Data
`
`US 2003/0098858 Al May 29, 2003
`
`* cited by examiner
`
`Primary Examiner—Bipin Shalwala
`Assistant Examiner—Ricardo Osorio
`
`(60)
`
`Related U.S. Application Data
`Provisional application No. 60/333,770,filed on Nov. 29,
`2001.
`
`(74) Attorney, Agent, or Firm—G.E. Ehrlich (1995) Ltd.
`
`(57)
`
`ABSTRACT
`
`Tint, C1 eee ececceeeeeeeeeeeeseeenneeneeneenees G09G 5/00
`(SL)
`Apparatus for user input to a digital system, comprising a
`(52) U.S. C1. cece erences 345/173; 345/179
`first sensing system for sensing a user interaction ofafirst
`(58) Field of Search .......00..00000 ee 345/173-179;
`type, co-located with a second sensing system for sensing a
`178/18.01-18.07, 19.01-19.06
`user interaction of a second type. The first system maydetect
`styluses and like objects using EM radiation and the second
`system may detect touch pressure.
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,231,381 A *
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`7/1993 Duwaer .......cc eee 345/174
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`15 Claims, 11 Drawing Sheets
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`Valve Exhibit 1076
`Valve Exhibit 1076
`Valve v. Immersion
`Valve v. Immersion
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`US 6,762,752 B2
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`1
`DUAL FUNCTION INPUT DEVICE AND
`METHOD
`
`RELATIONSHIP TO EXISTING APPLICATIONS
`
`The present application claims priority from U.S. Provi-
`sional Patent Application No. 60/333,770 filed Nov. 29,
`2001.
`
`FIELD AND BACKGROUND OF THE
`INVENTION
`
`The present invention relates to a digitizer and, more
`particularly, but not exclusively to a digitizer for accepting
`user input to a computing device.
`Input devices typically use one of three most popular
`technologies, movementtracking, as in a mouse, rollerball
`and like devices, touch technology as in a touch screen and
`pointing systemsas with a stylus. Different applications may
`be most suited to certain input technologies or systems.
`Touch technologies are commonly used as input devices
`for a variety of products. The use of touch digitizers is
`growing rapidly due to the emergence of new mobile
`devices, such as web pads, webtablets, Tablet—PC,wireless
`screens and hand-held computers. Such new mobile devices
`usually come without any integrated keyboard or mouse,
`due to mobility considerations, and therefore frequently use
`touch input devices. As well as mobile devices,
`touch
`digitizers are useful in computer systemsoffering services to
`the general public in shops and the like, where mice are
`likely to be broken or removed, and are also uscful for
`computers to be used in hazardous environments such as
`factory floors, since they allow the computer to be suitably
`sealed.
`
`To date, touch sensitive displays have been implemented
`using a variety of technologies for detecting touch stimuli.
`In one example, a transparent overlay is placed over a
`display. The overlay contains an array of sensors that can be
`resistive, conductive or capacitive. The sensors are arranged
`in rows and columns spanning the display screen area; and
`each sensor is therefore indicative of a particular touch
`location. Another technology involves the processing of an
`optical signal scanned across a CRT screen in order to
`determine a touch location. Yet another technology involves
`an array of force sensitive transducers that are mounted
`around the periphery of a display. Each transducer generates
`a different signal upon receiving a touch stimulus. The
`relative magnitudes of these signals can then be used to
`determine a touch location. The major drawback of these
`technologies and others is that
`they are all
`targeted at
`identifying the location of a single input (e.g. a stylus, a
`finger). None of these solutions supports multiple inputs
`simultaneously.
`With the emergence of Internet appliances such as Tablet
`PCs, the need for using a computer keyboard has become
`evident. Since connecting a standard keyboard to the Tablet
`PC diminishes the mobility of the device, the requirementto
`feed these devices with alphanumeric information is usually
`accomplished by the implementation of an “on-screen”
`keyboard. An “on-screen” keyboard is a scheme of a com-
`puter keyboard graphically illustrated on the display. Inputs
`are provided by successively touching the relevant graphical
`keys using a finger or a stylus. However, due to the inherent
`structure of existing touch technologies, it is impossible to
`support more than one touch (i.e. one key) at a time. This
`inherent property makes it impossible to apply the kind of
`convenient and intuitive keyboard operation known as
`“chord key”, for example “Shift’+“Letter” or “control”+
`“alt’+“delete”, at the same time.
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`2
`There had been attempts in the past to combine touch
`sensitive input devices with other kinds of digitizer. U.S.
`Pat. No. 4,686,332 by Grenians, describes a combination of
`a capacitance finger sensible sensor with an electromagnetic
`stylus, both incorporated in the same transparent foil. In
`Grenians,
`the same conductors are used for measuring
`capacitance and for transmitting the electromagnetic signal
`to the pick-up stylus. However,the device is forced to switch
`between methods and thereby work at a vastly degraded
`position report rate. An additional disadvantage of Grenians
`is the usage of a pick-up stylus, which acts as a receiver and
`therefore has to be either connected to the host system by
`wire or alternatively must use an internal battery and trans-
`mitter. Both pick-up arrangements are undesirable for
`mobile systems.
`USS. Pat. No. 5,231,381 to Duwaerdescribes a combina-
`tion of two independent sensors, one being sensitive to
`finger touch and the other being sensitive to stylus position,
`both incorporated in the same device. Duwaer’s device is
`capable of detecting finger touch and stylus simultaneously.
`However, the usage of two independent input sensors is a
`major disadvantage since it usually raises the price of the
`device. Furthermore, Duwaer’s device cannot detect multi
`finger touch and is therefore unable to support chord-key
`functionality.
`In US. patent application Ser. No. 09/628,334 “Physical
`Object Location Apparatus and Method and a Platform using
`the same”,
`to Perski et al, an electromagnetic pointing
`device using a transparent conductive overlay foil
`is
`described. The device is capable of detecting the location
`and identity of physical objects, such as a stylus, located on
`top of a display. The above electromagnetic technology
`enables the accurate position detection of one or more
`electromagnetic pointers, as well as sensing of multiple
`physical objects, for example playing pieces for use in
`games. However, the electromagnetic technology is inher-
`ently unable to sense a finger touch input, and is therefore
`inadequate for finger-based operation of an “on-screen” or
`virtual keyboard. The above-mentioned application is
`hereby incorporated herein by reference and the reader is
`referred thereto wherein a method that allows simultaneous
`detection of different styluses or playing pieces at different
`positions is described.
`In general, finger and stylus interactions require different
`detection techniques with different resolutions and different
`update levels. An attempt to use a single detection technique
`for both finger and stylus interactions is described in U.S.
`Pat. No. 5,543,589,
`to Buchana et al, which uses a four
`layer-two system transparentfoil arrangement. Both systems
`use the same touch detection method but have different
`
`resolution levels and update rates so that one can sense
`stylus type interactions and the other can sense finger touch
`type interactions. A disadvantage of the system is the higher
`price of using two sensing systems and that the use of four
`foil layers markedly reduces visibility of the underlying
`screen when used overa display. An additional disadvantage
`of Buchana’s system follows from the use of two similar
`sensing systems. Full mouse emulation, as an example,
`requires the tracking of the stylus position while hovering
`above the display. Such a feature cannot be supported by a
`pressure sensitive system, which is on the other hand essen-
`tial for finger touch detection.
`There is thus a widely recognized need for, and it would
`be highly advantageous to have, a digitizer devoid of the
`above limitations.
`
`SUMMARYOF THE INVENTION
`
`According to one aspect of the present invention there is
`provided apparatus for user input to a digital system, com-
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`US 6,762,752 B2
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`3
`prising a first sensing system havingfirst sensors for sensing
`a user interaction using a sensing methodofa first type, and
`a second sensing system having second sensors for sensing
`a user interaction using a sensing method of a second type,
`said first and second sensors being co-located on a sensing
`surface.
`
`Preferably, said first and said second sensing systems
`respectively are operable to sense simultaneously.
`Preferably, said sensing surface is superimposed on a
`display screen.
`Preferably, said sensing surface is superimposed on a part
`of said display screen.
`Preferably,a first of said sensing systems is superimposed
`on a part ofsaid display screen, and a secondofsaid sensing
`systems is superimposed substantially over an entirety of
`said display screen.
`Preferably, each one of said sensing systems is superim-
`posed on a respectively independently defined part of said
`display screen.
`Preferably, said first sensing system is a touch pressure-
`sensing system.
`Preferably, said second sensing system is an electromag-
`netic based sensing system.
`Preferably, said display screen is a flat panel screen.
`Preferably, at least one of said sensing systems comprises
`sensor reading operability for reading multiple simultaneous
`interactions with respective sensors.
`Preferably, said display screen is an LCD screen
`The apparatus preferably comprises a connectivity inter-
`face for allowing fitting as an accessory to a computing
`system.
`Preferably, said display screen is an electronic pad-type
`surface.
`
`Preferably, said co-located sensing systems are con-
`structed as a foil-based sensing arrangement.
`Preferably, said foil-based sensing arrangement com-
`prises at least one transparent foil.
`Preferably, at least some of said sensors comprise organic
`conductive material.
`
`Preferably, said transparent foil is a patterned transparent
`foil.
`
`Preferably, said pattern is etched onto said foil, thereby to
`form said sensors.
`
`Preferably, said pattern is printed on said foil, thereby to
`form said sensors.
`
`Preferably, said pattern is introduced by passivation.
`Preferably, said foil-based sensing arrangement com-
`prises at least two superimposed transparent foils.
`Preferably, sensors ofsaid first sensing system are embed-
`ded in each of said at least two superimposed transparent
`foils.
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`Preferably,said first and said second sensing systems have
`respectively different report rates for scanning respective
`sensors.
`
`Preferably, said respectively different report rates are
`selected for compatibility with a respective one of saidfirst
`and second user interaction type.
`Preferably,said first and said second sensing systems have
`respectively different sensing resolution levels.
`Preferably, said respectively different sensing resolution
`levels are selected for compatibility with a respective one of
`said first and second user interaction type.
`Preferably, said first sensing system is an electromagnetic
`based sensing system, said respective user interaction is
`stylus operation and said respective resolution level
`is
`selected for compatibility with a respective application.
`Preferably, said second sensing system is a pressure based
`sensing system, said respective user interaction is touch and
`said respective resolution level is selected for fingertip size.
`Preferably, said foil-based sensing arrangement com-
`prises two superimposed transparent foils, and wherein a
`first parallel arrangement of pressure-sensitive sensors is
`located on a first of said foils and a second parallel arrange-
`ment of pressure-sensitive sensors, orthogonal to said first
`parallel arrangement,is correspondingly located on a second
`of said foils.
`
`Preferably, said superimposed foils are spaced apart by a
`flexible spacer to be pressed together upon application of
`pressure.
`Preferably, said flexible spacer comprises a matrix of
`substantially non-conducting material with gaps, wherein
`said gaps are located to correspondto junctions between said
`first and second parallel arrangements of pressure-sensitive
`sensors, such that upon application of pressure at any given
`junction, corresponding sensors are brought into contact.
`Preferably, said substantially non-conducting material is
`located to separate between sensors of said first sensing
`system.
`Preferably, said flexible spacer comprises spacer dots,
`said spacer dots being concentrated about sensors of said
`first sensing system.
`Preferably, said flexible spacer is printed onto at least one
`of said foils.
`
`Preferably, each sensing system has a set of sensors
`located within said foil-based sensing arrangement, and
`wherein each set of sensors is arranged substantially as a
`grid.
`Preferably, each sensing system has an arrangement of
`sensors set out to define detection co-ordinates and at least
`
`one of said sensing systems comprises scanning control
`functionality for scanning said detection co-ordinates in a
`multi-stage scanning operation,
`thereby to home in on
`multiple locations.
`is a grid and said
`Preferably, said arrangement
`co-ordinates are Cartesian co-ordinates.
`
`Preferably, sensors of said second sensing system are
`embedded in each ofsaid at least two superimposedtrans-
`Preferably, said multi-stage scanning operation comprises
`parentfoils.
`a first stage of scanning groups of sensors along each axis of
`Preferably, sensors of said second sensing system are
`said grid, and a second stage of homing in on co-ordinates
`embedded in each of said at least two superimposed trans-
`indicated in said first stage.
`parentfoils.
`Preferably, said first stage comprises applying a sensing
`Preferably, sensors of said first and said second sensing
`signalto all sensors of each group inafirst axis, and reading
`systems respectively are interleaved in said foil-based sens-
`each sensorin said second axis, and then applying a sensing
`ing arrangement.
`signal to all sensors of each group in said second axis and
`reading each sensorin said first axis.
`Preferably, sensors of said first and said second sensing
`systems are interleaved in said first of said at least two
`Preferably, said scanning control functionality is operable
`superimposed transparentfoils.
`to determine whether an ambiguity is present, and, if an
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`Preferably, said scanning controller is operable to carry
`ambiguity is present to define suspect sensors as any sensor
`giving rise to a signal.
`out each of said two stages at substantially twice the
`Preferably, said scanning control functionality is further
`frequency of fastest likely changes in a pressure application
`pattern.
`operable to select each suspect sensor one at a timeinafirst
`of said axes, to apply a sensing signal thereto, and to read
`Accordingto a fourth aspect of the present invention there
`each suspect sensor in a second of said axes.
`is provided a method of sensing of a plurality of pressure
`According to a second aspect of the present invention
`sensitive points arranged in a grid for detection of simulta-
`there is provided a pressure sensing apparatus for detection
`neous applications of pressure at a plurality of said points,
`of at least two pressure locations, the apparatus comprising:
`the method comprising testing said grid such as to obtain an
`an arrangement of pressure sensors set out
`to define
`unambiguous pressure detection result for each of said
`detection co-ordinates, and
`pressure points in said grid.
`scanning control functionality for scanning said detection
`Preferably, said testing comprises:
`co-ordinates in a multi-stage scanning operation,
`outputting a signal to each of a plurality of sensors on one
`thereby to home in on said at
`least
`two pressure
`axis of said grid,
`locations.
`detecting at each of a plurality of sensors on a second axis
`According to a third aspect of the present invention there
`of said grid,
`is provided a sensor arrangement for superimposing, over a
`outputting a signal to each of said plurality of sensors on
`visual display screen, comprising:
`said second axis of said grid,
`a first transparent foil having sensors of a first detection
`system for detecting a user interaction of a first type,
`detecting at each of said plurality of sensors on saidfirst
`and sensors of a second detection system for detecting
`axis of said grid,
`a user interaction of a second type, embeddedtherein,
`from said detecting deducing sensors that are possible
`and
`sources of ambiguity, and
`conducting further outputting and detecting to resolve
`said ambiguity.
`Preferably, said conducting further outputting comprises
`selecting one of said axes and outputting a signal to each of
`said possible sources of ambiguity thereon, and said detec-
`tion comprises detecting at each of said possible sources on
`the other of said axes for each said outputting.
`Preferably, said testing comprises an exhaustive test of
`each of said pressure points individually.
`Unless otherwise defined, all
`technical and scientific
`terms used herein have the same meaning as commonly
`understood by one of ordinary skill in the art to which this
`invention belongs. The materials, methods, and examples
`provided herein are illustrative only and not intended to be
`limiting.
`Implementation of the method and system of the present
`invention involves performing or completing selected tasks
`or steps manually, automatically, or a combination thereof.
`Moreover, according to actual instrumentation and equip-
`mentof preferred embodiments of the method and system of
`the present invention, whilst part of the invention requires
`hardware, certain selected steps may be implemented by
`hardware or by software on any operating system or any
`firmware or
`a combination thereof. For example, as
`hardware, selected steps of the invention may be imple-
`mented as a chip or a circuit. As software, selected steps of
`the invention could be implemented as a plurality of soft-
`ware instructions being executed by a computer using any
`suitable operating system. In any case, selected steps of the
`method and system of the invention could be described as
`being performed by a data processor, such as a computing
`platform for executing a plurality of instructions.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`a second transparent foil superimposed over said first
`transparent foil and flexibly spaced therefrom, having
`further sensors ofsaid first detection system and of said
`second detection system embedded therein.
`According to a further aspect of the present invention
`there is provided a pressure sensing arrangement for super-
`imposing over a visual display screen, comprising:
`a first transparent foil havinga first set of parallel pressure
`sensors,
`
`a second transparent foil, superimposed over said first
`transparentfoil having a secondset of parallel pressure
`sensors, said transparentfoils being orientated such that
`said first and secondsets of transparentfoils are respec-
`tively orthogonal,
`a substantially non-conductive spacer located between
`said first transparent foil and said second transparent
`foil to separate between said foils, said spacer being
`flexible to allow contact between pressure sensors on
`respective foils about a point of application of pressure,
`thereby to transfer a signal between contacted pressure
`sensors, and
`a scanning controller for controlling a scanning operation
`to apply signals to said sensors and to read outputs in
`such a way as to provide unambiguouspressure infor-
`mation concerning every junction on a grid defined by
`said pressure sensors.
`Preferably, said scanning operation comprises twostages,
`a first stage of scanning groups of sensors on each foil, and
`a second stage of homing in on junctions indicated in said
`first stage, thereby to detect simultaneous applications of
`pressure at multiple points.
`Preferably, each scanning operation is an exhaustive scan-
`ning operation comprising individual testing of each junc-
`tion.
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`Preferably,said first stage comprises outputting a signalto
`each sensor on oneof said foils and detecting at each sensor
`on the other of said foils, then outputting a signal to each
`sensor on said other foil and detecting at each sensor on said
`one of said foils.
`Preferably, said second stage comprises outputting a sig-
`nal to each sensor, on one of said foils,
`that has been
`indicated in saidfirst stage, and detecting at each sensorthat
`has been indicated in said first stage on the other of said
`foils.
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`The invention is herein described, by way of example
`only, with reference to the accompanying drawings. With
`specific reference now to the drawingsindetail,it is stressed
`that the particulars shown are by way of example and for
`purposes of illustrative discussion of the preferred embodi-
`ments of the present invention only, and are presented in the
`cause of providing whatis believedto be the most useful and
`readily understood description of the principles and concep-
`tual aspects of the invention. In this regard, no attemptis
`made to show structural details of the invention in more
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`US 6,762,752 B2
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`7
`detail than is necessary for a fundamental understanding of
`the invention, the description taken with the drawings mak-
`ing apparentto those skilled in the art how the several forms
`of the invention may be embodied in practice.
`In the drawings:
`FIG. 1 is a simplified block diagram of a dual technology
`sensor according to a first preferred embodiment of the
`present invention;
`FIG. 2 is a screen display showing a virtual keyboard;
`FIG. 3 is a schematic diagram showing conductors laid
`out
`in a two-layer sensing arrangement according to a
`preferred embodiment of the present invention;
`FIG. 4 is a simplified diagram showing an enlargementof
`one of the foils of the arrangement of FIG. 3;
`FIG. 5 is a simplified vertical cross-sectional diagram
`showing two foils superimposed upon each one another and
`separated by spacers,
`in accordance with a preferred
`embodimentof the present invention;
`FIG. 6 is a simplified diagram showing a view from above
`of a separation layer for placing between the foils;
`FIG. 7 is a simplified block diagram of a preferred
`embodimentof the digital processing unit of FIG. 1;
`FIG. 8 is a simplified schematic diagram showing appa-
`ratus for detecting a single touch;
`FIG. 9 is a simplified flow chart showinga first preferred
`embodimentof a procedure for detecting simultaneous mul-
`tiple touches on a sensor;
`FIG. 10 is a simplified flow chart showing a second, more
`efficient, embodiment of a procedure for detecting simulta-
`neous multiple touches on a sensor; and
`FIG. 11 is a simplified flow chart showing a third, more
`accurate, embodimentof a procedure for detecting simulta-
`neous multiple touches on a sensor.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`The present embodiments disclose a patterned transparent
`conductive foil system, able to detect the location and if
`relevant, identity, of physical objects, and further to enable
`finger inputs directly on the display. The primary use of the
`embodiments is to allow both stylus operation and the
`natural and intuitive finger operation of an “on-screen” or
`virtual keyboard. The embodiments are particularly useful
`for incorporation into mobile devices since they provide a
`single digitiser system. However they are useful as an
`intuitive and flexible data entry or user interaction system in
`any circumstances where users need to interact with a
`computer system.
`The present embodiments also disclose a touch screen
`able to sense multiple simultaneous touches, and thus to
`support so-called chord key operations.
`The embodiments may thus be used to support virtual
`keyboards in such a way as to overcomethe disadvantages
`of the above-described prior art technologies. The embodi-
`ments combine electromagnetic and touch-sensitive tech-
`nologies in a single transparent foil system. In addition, the
`preferred embodiments enable the detection of more than a
`single touch input at the same time, thereby enabling chord
`key operation.
`Morespecifically, embodiments of the present invention
`provide a new type of a flat panel display digitizer support-
`ing both the detection, using electromagnetism, of physical
`objects, such as a stylus, and the detection of finger touch
`operations using a single transparent overlay foil system.
`
`10
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`15
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`20
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`25
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`30
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`40
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`45
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`50
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`55
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`60
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`8
`Embodiments may be provided as a built in part of a
`computing system or as an add-on accessory.
`The principles and operation of a digitizer according to
`the present invention may be better understood with refer-
`ence to the drawings and accompanying descriptions.
`Before explaining at least one embodimentof the inven-
`tion in detail, it is to be understood that the invention is not
`limited in its application to the details of construction and
`the arrangement of the componentsset forth in the following
`description or illustrated in the drawings. The invention is
`capable of other embodiments or of being practiced or
`carried out in various ways. Also, it is to be understood that
`the phraseology and terminology employedhereinis for the
`purpose of description and should not be regarded as lim-
`iting.
`Reference is now made to FIG. 1, which is a simplified
`block diagram showing an integrated technology digitizer
`according to a first preferred embodiment of the present
`invention. Digitizer 10, for incorporation into for example a
`mobile computing device, comprises a transparent sensing
`arrangement 12, which combines electromagnetic and touch
`sensitive transparent conductors. The sensor arrangement 12
`is typically located over an LCD orother kinds of computer
`display. Front-end ASICs 14, preferably mounted on the
`frameof the sensor, process and sample signals output by the
`electromagnetic sensor conductors. The sampled signals are
`preferably forwarded to digital processing unit 16 through
`data bus 18 dedicated to the electromagnetic subsystem and
`hereafter referred to as an electromagnetic (EM) bus 18. A
`resistive bus 20 transfers touch signals between the digital
`unit 16 and the touch sensors. In the case of touch signals,
`signal transfer along the bus is bi-directional, as will be
`explained in greater detail below.
`The digital unit 16 preferably processes both electromag-
`netic and touch-sensitive signals. As will be explained in
`greater detail below, the outcomeof processingis a series of
`positions of electromagnetically located and/or identified
`objects, for example one or more styluses, and the positions
`of one or more fingers that touch the sensor. The digital
`processor output is preferably forwarded to host computing
`device 22 via interface 24. In a preferred embodiment the
`digital unit communicates with the host via a simple serial
`interface. Additional interfaces, such as USB, mayalso be
`used.
`
`The host computer preferably interprets stylus position
`and mode as mouse inputs. Reference is now madeto FIG.
`2 whichis a simplified screen illustration showing a typical
`display 30 on a mobile computing device that uses a virtual
`keyboard. A virtual keyboard 32 of the kind that may
`typically be provided on a host screen display is shown. The
`virtual keyboard comprises illustrations of standard key-
`board keys arranged in a standard keyboard layout. The user
`is able to touch the screen at a point corresponding to a key
`in the display, using either a finger or a pointing device such
`as a stylus, and the detected locations are interpreted as the
`corresponding keyboard inputs.
`In a preferred embodimentof the present invention, touch
`detection is extended only to the lowerpart of the screen, in
`which the keyboard is likely to be located, whereas stylus
`sensing extends to the entire screen. Such an embodiment
`leads to a reduction in the numberofparts, and thus reduced
`cost coupled with greater reliability. The skilled person will
`appreciate that other arrangements are possible, including
`having each sensing system restricted to only part of the
`screen.
`
`In US. patent application Ser. No. 09/628,334 an elec-
`tromagnetic based sensing device is described which is
`
`

`

`US 6,762,752 B2
`
`9
`capable of detecting physical objects, such as styluses,
`located on top of a flat panel display. An embodiment
`disclosed therein comprises a system built of two transparent
`foils, preferably patterned with organic conductivelines, one
`containing a set of vertical conductors and the other a set of
`horizontal conductors. The physical object contains a reso-
`nance circuit, which is energized by an excitation coil that
`surrounds the two sets of foils. A trigger signal for energiz-
`ing is preferably provided by a signal generator at preset
`intervals. The exact position of the physical object is deter-
`mined by processing signals issued by the physical object as
`a result of being thus energized. The signals as issued are
`sensed by the grid of horizontal and vertical conductors.
`Sensing resolution is higher than the grid size since signal
`processing allowsfor interpolation between the surrounding
`sensors.
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`10
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`15
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`10
`stripes 50 and 52, used for sensing touch pressure, are
`patterned between conductive lines 54, 56 and 58 that are
`used as electromagnetic antennas. In this manner, conduc-
`tive stripes are patterned in between pairs of conductive
`lines on each of two foils. The two foils are then superim-
`posed to form a two dimensional grid comprising horizontal
`stripes located on one transparent foil, and vertical stripes
`located on the other transparent foil.
`Reference is now made to FIG. 5, which is a simplified
`vertical cross-sectional diagram showing two foils superim-
`posed upon one another and separated byspacers, in accor-
`dance with a preferred embodimentof the present invention.
`Two foils, 60 and 62, respectively contain horizontal
`sensor patterns and vertical sensor patterns. The foils are
`assembled one on top of the other, and are separated by a
`non-conductive separation layer 64. Each foil has a conduc-
`tive surface, 66 and 68 respectively. The foils are arranged
`so that the conductive side of each foil faces the other foil.
`
`As with the above application, in a preferred embodiment
`of the present inventi