(12) United States Patent
`Wilson et al.
`
`USOO650453OB1
`(10) Patent No.:
`US 6,504,530 B1
`(45) Date of Patent:
`Jan. 7, 2003
`
`(54)
`
`(75)
`
`(73)
`
`(*)
`
`(21)
`(22)
`
`(51)
`(52)
`
`(58)
`
`(56)
`
`TOUCH CONFIRMING TOUCHSCREEN
`UTILIZING PLURAL TOUCH SENSORS
`
`Inventors:
`
`Geoffrey D. Wilson, Oxnard, CA (US);
`Victor E. Borgnis, Fremont, CA (US);
`Joel Kent, Fremont, CA (US); Mike
`Lewis, Oakland, CA (US); Drew
`Loucks, San Jose, CA (US); James
`Roney, Fremont, CA (US); Michael
`Bruno Patti, San Francisco, CA (US)
`ELO Touchsystems, Inc., Fremont, CA
`(US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`Appl. No.:
`09/390,207
`Sep. 7, 1999
`Filed:
`
`ASSignee:
`
`Notice:
`
`Int. C.7.
`
`- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - G09G 5/00
`
`U.S. C. ...
`
`- - - - - - - - - - - - - - - - - - - - 345/173; 34.5/174; 34.5/175;
`
`345/177
`
`Field of Search ................................. 345/173, 168,
`345/174, 175, 176, 177, 178, 179
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,103.252 A
`7/1978 Bobick
`3/1979 Eichelberger et al.
`4,145,748 A
`4/1981 Bigelow
`4.264,903 A
`(List continued on next page.)
`FOREIGN PATENT DOCUMENTS
`
`DE
`EP
`EP
`EP
`GB
`WO
`WO
`WO
`
`93 16 1948
`O372 964 A2
`O 727 875 A1
`O 795 837
`1.
`2 295 O17
`WO 88/05577
`WO95/27334
`WO 96/15464
`
`3/1995
`6/1990
`8/1996
`9/1997
`5/1996
`7/1988
`10/1995
`5/1996
`
`- - - - - - - - - - - G06F/3/037
`
`- - - - - - - - - - - GO6K/11/08
`
`- - - - - - - - - - - GO6KA11/18
`
`
`
`-
`
`PROCESSOR
`
`3.13
`
`OTHER PUBLICATIONS
`Patent Abstracts of Japan, vol. 017, No. 529 (P-1618), Sep.
`22, 1993 & JP 05 143226 A (Sharp Corp), Jun. 11, 1993.
`“Combining Laser and Piezoelectric Touchscreens”, IBM
`Technical Disclosure Bulletin, vol. 31, No. 2 Jul. 1988, p.
`137 XP-002168304, IBM Corp., New York.
`PCT Search Report, PCT/US00/29784, filed Oct. 17, 2000.
`Primary Examiner Steven Saras
`Assistant Examiner William C. Spencer
`(57)
`ABSTRACT
`A method and apparatus for discriminating against false
`touches in a touchscreen System is provided. The System is
`designed to confirm a touch registered by one touch Sensor
`with another touch Sensor, preferably of a different Sensor
`type, prior to acting upon the touch (i.e., sending touch
`coordinates to the operating System). If the touch registered
`by the first touch sensor is not confirmed by the second touch
`Sensor, the touch is invalidated. Thus the Strengths of one
`type of Sensor are used to overcome the deficiencies of
`another type of Sensor. In one aspect, the Secondary touch
`Sensor comprises a force Sensor to discriminate between true
`and false touches on other types of touch Sensors, Such as
`contaminants on optical and Surface acoustic wave Sensors,
`noise or weak signals on capacitive Sensors, etc. The force
`Sensor may be a simple one-element System that merely
`indicates that a touch has occurred or a multi-element
`System that can provide confirming or Supplementary coor
`dinate data. In another aspect, a capacitive Sensor is used to
`confirm or veto touch data from optical, Surface acoustic
`wave, and force Sensors. AS is the case with the Secondary
`force Sensor, a Secondary capacitive Sensor may be a simple
`discrete type or capable of providing touch coordinates in its
`own right. In a specific embodiment, one in which no touch
`overlay is used on a CRT monitor, the Secondary touch
`Sensor may employ the resistive coating on the Surface of the
`CRT in combination with a current monitoring circuit that
`measures the amplitude of the electromagnetic noise Signal
`coupled to the resistive coating. In this application when the
`Screen is touched by a grounded object, the detected Signal
`amplitude change exceeds a preset threshold thus indicating
`a valid touch.
`
`8 Claims, 9 Drawing Sheets
`
`801
`
`MONITOR
`
`- 311
`DISCRIMINATOR
`
`Petitioners Samsung and Sony Ex-1006, 0001
`
`

`

`US 6,504,530 B1
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`4,644,100 A 2/1987 Brenner et al.
`4,686,332 A 8/1987 Greanias et al.
`4,700,176 A 10/1987 Adler
`4,778,951 A 10/1988 Pepper, Jr. et al.
`RE33,151 E
`1/1990 Adler
`4,924.222 A 5/1990 Antikidis et al.
`4.954823 A 9/1990 Binstead
`5,117,071 A 5/1992 Greenias et al.
`5,231,381 A 7/1993 Duwaer
`5,270,711 A 12/1993 Knapp
`5,332,238 A 7/1994 Borucki
`5,510,813 A 4/1996 Makinwa
`
`5,543,589 A 8/1996 Buchana et al.
`5,650,597 A
`7/1997 Redmayne
`5,670.755 A
`9/1997 Kwon
`5,708.461 A 1/1998 Kent
`5,742,119 A 4/1998 Aben et al.
`5,777,607 A
`7/1998 Koolen
`5,790,106 A 8/1998 Hirano et al.
`5,801,682 A 9/1998 Coni et al.
`5,844,506 A 12/1998 Binstead ...................... 341/34
`5,854,450 A 12/1998 Kent
`6,281.888 B1 * 8/2001 Hoffman et al. ............ 345/179
`6,297.811 B1 10/2001 Kent et al. .................. 345/173
`* cited by examiner
`
`Petitioners Samsung and Sony Ex-1006, 0002
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 1 of 9
`
`US 6,504,530 B1
`
`
`
`
`
`
`
`
`
`
`
`FIG. 1
`
`FIG 2
`
`STAND-BY STATUS
`
`SCREEN TOUCHED
`
`1 O1
`
`
`
`
`
`
`
`
`
`
`
`STAND-BY STATUS
`
`SCREEN TOUCHED
`
`
`
`
`
`
`
`TOUCH REGISTERED BY
`PRIMARY SENSOR
`
`TOUCH REGISTERED BY
`PRIMARY SENSOR
`
`1O7
`
`TOUCH
`REGISTERED
`BY SECONDARY
`SENSORP
`
`YES
`TOUCH POSITION
`CONFIRMED
`
`TOUCH POSITION
`DETERMINED
`
`
`
`
`
`
`
`TOUCH POSITION SENT
`TO OPERATING SYSTEM
`
`
`
`
`
`
`
`109
`
`111
`
`113
`
`TOUCH POSITION
`DETERMINED
`
`TTSET SECONDARY
`TOUCH THRESHOLD
`
`t
`
`REGISTERED
`BY SECONDARY
`SENSOR2
`
`
`
`YES
`TOUCH POSITION
`CONFIRMED
`
`TOUCH POSITION SENT
`TO OPERATING SYSTEM
`
`
`
`
`
`
`
`109
`
`2O3
`
`Petitioners Samsung and Sony Ex-1006, 0003
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 2 of 9
`
`US 6,504,530 B1
`
`PROCESSOR
`
`DISCRIMINATOR
`
`313
`
`311
`
`FIG 3
`
`
`
`
`
`FIG. 4
`
`Petitioners Samsung and Sony Ex-1006, 0004
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 3 of 9
`
`US 6,504,530 B1
`
`507
`
`
`
`505
`
`305
`
`MONITOR
`
`FIG. 5
`
`
`
`6O4
`606
`
`Petitioners Samsung and Sony Ex-1006, 0005
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 4 of 9
`
`US 6,504,530 B1
`
`
`
`3
`
`% & % %
`2 6 3 S
`
`S
`
`s
`
`Petitioners Samsung and Sony Ex-1006, 0006
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 5 of 9
`
`US 6,504,530 B1
`
`S
`
`
`
`Petitioners Samsung and Sony Ex-1006, 0007
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 6 of 9
`
`US 6,504,530 B1
`
`PRIMARY SENSOR TW
`STAND-BY MODE
`
`901
`
`SECOWDARY SENSOR INI-90.3
`ACTIVE MODE
`
`TOUCH DETECTED BY
`SECONDARY SENSOR
`
`905
`
`PRIMARY SENSOR
`ACTIVA TED
`
`907
`
`TOUCH CONFIRMED AND
`POSITION COORDINATE
`DETERMINED AND SENT-909
`TO THE OPERATING
`SYSTEM
`
`FIG. 9
`
`
`
`
`
`1001
`
`IR SENSOR
`REGISTERS TOUCH
`
`
`
`
`
`
`
`
`
`TOUCH
`REGISTERED
`BY FORCE
`SEWSORS2
`
`1OO7
`
`
`
`REPORT TOUCH
`COORDINATES
`
`FIG 10
`
`Petitioners Samsung and Sony Ex-1006, 0008
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 7 of 9
`
`US 6,504,530 B1
`
`1 OO1
`
`
`
`
`
`IR SENSOR
`REGISTERS TOUCH
`
`
`
`
`
`
`
`
`
`
`
`TOUCH
`REGISTERED
`BY FORCE
`SENSORS2
`
`REGISTERED
`TOUCH GREATER
`THAN THRESHOLD
`2
`
`1105
`REPORT TOUCH
`COORDINATES
`
`
`
`Petitioners Samsung and Sony Ex-1006, 0009
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 8 of 9
`
`US 6,504,530 B1
`
`
`
`
`
`s
`N
`
`N
`
`s
`
`S.
`
`s
`
`S
`
`s
`
`s
`
`O N sS
`
`
`
`S Q
`S
`r s
`S
`S. N
`
`Q
`
`Petitioners Samsung and Sony Ex-1006, 0010
`
`

`

`U.S. Patent
`
`Jan. 7, 2003
`
`Sheet 9 of 9
`
`US 6,504,530 B1
`
`FIG 16
`
`15O1
`
`1503
`
`
`
`1505
`
`
`
`15O7
`
`SYSTEM IN SLEEP MODE
`
`WAKE-UP TOUCH REGISTERED
`BY FORCE SENSOR SYSTEM
`
`ARIMARY SENSOR SYSTEM
`ACTIVATED
`
`PRIMARY SENSOR REGISTERS
`SUCCESSIVE TOUCH
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`TOUCH
`REGISTERED
`BY FORCE
`SENSORS2
`
`
`
`REPORT TOUCH
`COORDIWATES
`
`
`
`SUCCESSIVE
`TOUCH REGISTERED
`WITH IN TIME
`LIMIT?
`
`1515
`
`Petitioners Samsung and Sony Ex-1006, 0011
`
`

`

`1
`TOUCH CONFIRMING TOUCHSCREEN
`UTILIZING PLURAL TOUCH SENSORS
`
`US 6,504,530 B1
`
`2
`by a finger, Stylus, etc. to be detected by both Sensors. In use,
`the wide conductors of the low resolution sensor are first
`Scanned in order to determine touch position to within a
`rectangular area the Size of one wide conductor. To deter
`mine the touch location with the higher resolution Sensor,
`only the narrow conductors corresponding to the rectangular
`area of touch determined with the low resolution Sensor
`must be Scanned. Thus the System disclosed is intended to
`reduce the number of Scan drivers and receiverS required,
`thus lowering cost as well as Speeding up the Scanning
`proceSS.
`U.S. Pat. No. 5,670,755 discloses a touch panel that can
`be used in either of two modes. In one mode, the touch panel
`operates like a conventional touchscreen, allowing a user to
`input information by touching the Screen with a finger, pen,
`or other touching medium. In this mode two resistive layers
`applied to the panel come into contact at the point of touch.
`The determination of the contact location is based on
`resistance ratios. In a Second mode, the touch panel func
`tions as a digitizer using a specially designed Stylus. Capaci
`tance coupling at the contact point of the Stylus to the panel
`is used in determining the contact point.
`U.S. Pat. No. 5,777,607 discloses a system that senses
`finger touch capacitively and Stylus touch resistively. In
`either touch mode the disclosed System is able to determine
`the X- and y-coordinates of the touch on the touchscreen
`using a single resistive layer. In the preferred embodiment,
`the finger detection mode is disabled when the System
`detects the Stylus is in use, thus preventing the inadvertent
`input of data through capacitive coupling with the user's
`hand.
`U.S. Pat. No. 5,801,682 discloses a dual sensor touch
`Screen in which the variations in coordinate data from a
`capacitive Sensor are compensated for by the use of Strain
`gauges mounted at the corners of the Sensor. Variations in the
`capacitive Sensor data may result from changes in Signal
`path, for example, due to the user wearing gloves.
`What is needed in the art is a method and apparatus for
`discriminating against false touches of the Sort that may
`result from external Stimuli Such as Vibration, electrical
`noise, and contaminants, or for confirming the presence of
`touch. The present invention provides Such a method and
`apparatuS.
`
`TECHNICAL FIELD OF THE INVENTION
`The present invention relates generally to touchscreens
`and, more particularly, to a method and apparatus for dis
`criminating between a false touch event and a true touch on
`a touchscreen.
`
`5
`
`15
`
`25
`
`35
`
`BACKGROUND OF THE INVENTION
`Touchscreens are used in conjunction with a variety of
`display types, including cathode ray tubes (i.e., CRTs) and
`liquid crystal display Screens (i.e., LCD Screens), as a means
`of inputting information into a data processing System.
`When placed over a display or integrated into a display, the
`touchscreen allows a user to Select a displayed icon or
`element by touching the Screen in a location corresponding
`to the desired icon or element. Touchscreens have become
`common place in a variety of different applications
`including, for example, point-of-Sale Systems, information
`kiosks, automated teller machines (i.e., ATMs), data entry
`Systems, etc.
`A variety of touchscreen types have been developed.
`Unfortunately each type of touchscreen has at least one
`weakness limiting its usefulneSS in at least Some applica
`tions. For example, the cover sheet in a resistive touchscreen
`is Susceptible to damage. Even repeated Screen compres
`Sions may eventually damage a resistive touchscreen. This
`type of touchscreen is also Susceptible to environmental
`damage, for example moisture entering the display. A Second
`type of touchscreen, capacitive touchscreens, are non
`responsive to touch from an ungrounded object, thus leading
`to potential problems with gloved hands, Styluses, pencils,
`etc. A third type of touchscreen utilizing Surface acoustic
`waves is Susceptible to the accumulation of contaminants
`(e.g., water) on the Surface of the Sensor. Contamination can
`also interfere with the operation of infrared touchscreens. A
`fifth type of touchscreen using force Sensors is Susceptible to
`40
`Shock and Vibration.
`Various Systems have been designed that utilize two
`different touchscreen technologies for a variety of purposes,
`primarily as a means of accommodating different touch
`mechanisms, e.g., a finger and a Stylus, for data entry.
`U.S. Pat. No. 5,231,381 discloses a multi-purpose data
`input device utilizing an integrated touchscreen and a digi
`tizing tablet. The touchscreen detects the presence and
`location of a passive input (e.g., finger touch) through any of
`a variety of techniques including Surface acoustic wave,
`force, capacitive, or optical touch Sensors. The digitizing
`tablet employs an active Stylus mechanism to Stimulate a
`capacitive, inductive, or Surface acoustic wave Sensor.
`U.S. Pat. No. 5,510,813 discloses a touch panel that
`measures both touch position and touch force. The touch
`panel uses a resistive, conductive layer and determines touch
`position by monitoring the current pattern. The force of the
`touch is determined by monitoring a capacitance value
`between the touch panel and a Second conductive panel that
`extends Substantially parallel to the touch panel. In response
`to a touch, the System processes both the detected position
`and the detected force of the touch.
`U.S. Pat. No. 5,543,589 discloses a dual sensor touch
`Screen in which each Sensor determines touch position, but
`with a different resolution. The two sensors are Sandwiched
`together to form a Single Sensor, thus allowing a single touch
`
`45
`
`50
`
`55
`
`60
`
`65
`
`SUMMARY OF THE INVENTION
`The present invention provides a method and apparatus
`for discriminating against false touches in a touchscreen
`System. The System utilizes multiple touchscreen Sensors of
`differing types to validate a touch on a touchscreen. Thus the
`invention utilizes the Strengths of Specific Sensor types to
`overcome the deficiencies of other Sensor types.
`The basis of the invention lies in the ability to confirm a
`touch registered by one touch Sensor with another touch
`Sensor. If the touch is confirmed, the touch can be acted
`upon, for example by Sending touch coordinates to the
`operating System. If, on the other hand, the touch is not
`confirmed, the touch is invalidated. The System can be
`designed Such that there is a primary touch Sensor that
`determines the touch coordinates and a Secondary Sensor
`that validates the presence of a touch, by either a discrete
`Signal or by generating a Second Set of touch coordinates for
`comparison purposes. Furthermore, the touch coordinates
`can either be determined before or after the initial touch is
`confirmed.
`In one embodiment of the invention, the Secondary touch
`Sensor comprises a force Sensor to discriminate between true
`
`Petitioners Samsung and Sony Ex-1006, 0012
`
`

`

`3
`and false touches, false touches being caused by Such factors
`as contaminants (e.g., problematic for optical and Surface
`acoustic wave sensors), noise or weak signals (e.g., prob
`lematic for capacitive sensors), etc. In this embodiment,
`when the preSSure that is applied to the touch Screen exceeds
`a predetermined threshold, the touch coordinates are vali
`dated. In contrast, when a false touch signal is generated by
`the primary Sensor, for example due to a raindrop falling on
`a Surface acoustic wave Sensor, the lack of a confirming
`touch pressure on the Secondary force Sensor causes the data
`to be declared invalid. The Secondary force Sensor may be a
`Simple one-element System that merely indicates that a touch
`has occurred by Sensing touch preSSure, or a multi-element
`force touch System that can provide confirming or Supple
`mentary coordinate data.
`In another embodiment, a capacitive Sensor is used to
`confirm or Veto the touch data from optical, Surface acoustic
`wave, or force Sensors. In this embodiment, when the
`Secondary capacitive Sensor is touched by a grounded con
`ductor Such as a finger, the resulting current flow indicates
`a valid touch detection by the primary Sensor.
`In contrast, a false touch due to either a contaminant (e.g.,
`Surface acoustic wave or optical sensors) or a shock or
`vibration (e.g., force-based touch System) does not result in
`a coincident current flow in the capacitive Secondary Sensor,
`thus invalidating the data from the primary Sensor. The
`Secondary capacitive Sensor may be a simple discrete Sensor
`Such as that provided by a Single-contact transparent con
`ductive coating or a more complex capacitive Sensor capable
`of providing touch coordinates for comparison purposes.
`In another embodiment of the invention, one in which no
`touch panel is overlaid on the face of a CRT monitor (e.g.,
`infrared optical System, on-tube Surface acoustic wave
`System, or a non-overlay differential force System), the
`Secondary capacitive Sensor is comprised of a resistive
`coating on the Surface of the CRT. A resistive coating of this
`type may be used to limit charge build-up on the CRT
`Screen. The capacitive Sensor of this embodiment utilizes the
`resistive coating in combination with a current monitoring
`circuit that measures the amplitude of the electromagnetic,
`noise Signal coupled to the resistive coating. In use, when the
`Screen is touched by a grounded object Such as a finger, the
`detected Signal amplitude change exceeds a preset threshold
`thus indicating a valid touch. In contrast, when an
`ungrounded object Such as a contaminant touches the
`Surface, the detected Signal amplitude change does not
`exceed the preset threshold and the touch is invalidated.
`In another embodiment of the invention, a Secondary
`Sensor Such as a force Sensor or a capacitive Sensor is used
`as a means of adding tactile feel to an IR optical Sensor based
`touchscreen. In this embodiment the Secondary Sensor Sys
`tem is used to determine when the user has made physical
`contact with the touchscreen. Until actual contact is made,
`the IR system will not register a touch, thus eliminating false
`touches that may arise due to the user or an article of the
`user's clothing interrupting the IR beam grid. In addition,
`the Secondary Sensor System can be used when the System is
`in a Sleep mode, thus eliminating the continuous power drain
`associated with the IR system.
`A further understanding of the nature and advantages of
`the present invention may be realized by reference to the
`remaining portions of the Specification and the drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a flow chart illustrating the basic methodology
`of the present invention;
`
`4
`FIG. 2 is a flow chart illustrating an alternate methodol
`ogy of the present invention;
`FIG. 3 is an illustration of an embodiment of the present
`invention utilizing a simple capacitive false touch Sensor in
`conjunction with either an infrared or a Surface acoustic
`Wave Sensor,
`FIG. 4 is an illustration of an alternative embodiment to
`that shown in FIG.3 utilizing a simple capacitive false touch
`Sensor in conjunction with a non-overlay differential force
`Sensor,
`FIG. 5 is a cross-sectional view of a capacitive touch
`Sensor,
`FIG. 6 is an illustration of one or more force sensors
`mounted to a touchscreen;
`FIG. 7 is an illustration of an embodiment of the present
`invention utilizing a Surface acoustic wave Sensor as the
`primary Sensor and one or more force Sensors as the Sec
`ondary Sensor;
`FIG. 8 is an illustration of an embodiment of the present
`invention utilizing a capacitive Sensor as the primary Sensor
`and one or more force Sensors as the Secondary Sensor;
`FIG. 9 is a flow chart illustrating the system wake-up
`feature according to the present invention;
`FIG. 10 is a flow chart illustrating the methodology
`asSociated with an embodiment of the invention utilizing a
`force Sensor System in conjunction with an IR optical Sensor
`System;
`FIG. 11 is a flow chart illustrating an alternate method
`ology associated with an embodiment of the invention
`utilizing a force Sensor System in conjunction with an IR
`optical sensor System;
`FIG. 12 is an illustration of an embodiment of the
`invention utilizing an IR optical Sensor System as the pri
`mary Sensor and a force Sensor System as the Secondary
`Sensor,
`FIG. 13 is a cross-sectional view of a variation of the
`optical Sensor/force Sensor based embodiment of the inven
`tion;
`FIG. 14 is a cross-sectional view of an alternate variation
`of the optical Sensor/force Sensor based embodiment of the
`invention; and
`FIG. 15 is a flow chart illustrating the use of a force sensor
`to provide a legitimate Sleep mode.
`
`DESCRIPTION OF THE SPECIFIC
`EMBODIMENTS
`FIG. 1 is a flow chart illustrating the preferred operation
`of the present invention. At step 101, the touchscreen is in
`a pre-touch, Stand-by Status. The Screen then receives a
`touch (step 103), for example via a finger, Stylus, or other
`means. The primary touch sensor then registers a touch (Step
`105). The sensor used in step 105 can be of any type, for
`example, resistive, capacitive, Surface acoustic wave,
`infrared, or force. Prior to the primary touch Sensor deter
`mining the coordinates of the touch or Sending any infor
`mation to the operating System (e.g., touch position, touch
`mode, etc.), a secondary Sensor confirms that the touch
`received by the primary sensor is a valid touch (step 107).
`If the Secondary Sensor confirms that the touch is valid (Step
`109), the touch position is determined (step 111). Depending
`upon the desired configuration, the touch position can be
`determined by either the primary Sensor or the Secondary
`Sensor. The touch controller then sends the touch informa
`tion to the operating System (step 113). If the Secondary
`
`US 6,504,530 B1
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Petitioners Samsung and Sony Ex-1006, 0013
`
`

`

`S
`Sensor does not confirm that a valid touch was received by
`the primary Sensor, no touch information is Sent to the
`operating System and the touch Sensor is placed back into
`stand-by status 101. The benefit of this embodiment is that
`time is not spent on determining invalid touch positions, thus
`enabling the System to quickly confirm that a valid touch has
`been received and if the touch is invalidated, to quickly
`return to stand-by status 101.
`In a slight modification of the system illustrated in FIG.
`2, after the primary Sensor registers a touch (step 105), it
`determines the position of the touch (step 201). After deter
`mining touch position, the System can Simply query the
`Secondary Sensor to determine it has also registered a touch
`(step 107) and if it has, confirm the touch (step 109) and send
`the position coordinates to the operating System (step 203).
`Alternately, after the touch position has been determined
`(step 201), a coordinate dependent touch threshold is set for
`the Secondary Sensor (step 205), thus accounting for coor
`dinate dependent touch Sensitivities.
`In the preferred embodiment of the invention, one of the
`Sensors, preferably the Secondary Sensor, only determines
`whether or not a touch has been received. Since this Sensor
`does not determine absolute touch position, it can be an
`inexpensive Sensor. Alternately, this Sensor is designed to
`determine approximate touch position. For example, this
`Sensor can be designed to determine what quadrant of the
`Screen has been touched. Alternately, the complimentary
`information received from the two Sensors is used to refine
`the received touch information. For example, the informa
`tion received from the first Sensor can be used to adjust the
`touch threshold of the second sensor.
`FIGS. 3 and 4 illustrate two configurations of an embodi
`ment of a false touch discrimination touchscreen System
`according to the present invention. In both configurations
`the front surface of a display 301 (e.g., a CRT screen)
`includes a resistive coating. The coating may be of the type
`that is commonly deposited on CRT Screens to limit charge
`build-up, for example, an ITO coating. The primary touch
`Sensor can be any of a variety of different touch Screens
`although it is preferably a Surface acoustic wave (i.e., SAW)
`sensor Such as that disclosed in U.S. Pat. Nos. 5,708.461, a
`non-overlay differential force Sensor Such as that disclosed
`in U.S. Pat. No. 5,038,142, or an infrared touch sensor Such
`as that disclosed in U.S. Pat. No. 5,164,714, the disclosures
`of which are incorporated herein for all purposes.
`FIG. 3 shows a touchscreen system 300 in which the
`primary Sensor is either a SAW Sensor or an infrared Sensor.
`In this embodiment screen 301 includes a plurality of
`emitter/receivers 303 along the periphery of the front surface
`of the display screen, emitter/receivers 303 designed for use
`with either a SAW sensor or an infrared sensor. In the
`alternative configuration shown in FIG. 4, the primary
`sensor of touchscreen system 400 utilizes a non-overlay
`differential force Sensor System with four force measuring
`gauges 401, one at each corner of Screen 301.
`To provide the Secondary or false touch Sensor in touch
`screen systems 300 and 400, the resistive coating on screen
`301 is coupled to an electric field monitor 305, preferably
`via an electrode 307. Electrode 307 can be positioned behind
`a monitor cowling, thus hiding the connection from View by
`the user. When the CRT is in use, a field is generated by the
`anode Supply of the CRT, thereby causing electromagnetic
`noise. Capacitive coupling of the high Voltage anode ripple
`to the resistive coating of screen 301 contributes to this
`signal. Monitor 305 measures the voltage difference
`between the resistive coating and a ground 309 that corre
`sponds to the CRT's ground.
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`US 6,504,530 B1
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`6
`In use, when a finger or other grounded object touches
`CRT front screen 301 (i.e., the resistive coating), the ampli
`tude of the signal observed by monitor 305 changes. Monitor
`305 is coupled to a discriminator 311 that determines when
`a change in the detected Signal amplitude is greater than a
`preset threshold, thus indicating that a touch has occurred.
`Thus discriminator 311 distinguishes between grounded
`objects Such as a user's finger and ungrounded objects Such
`as a water droplet.
`Discriminator 311 and the primary touch sensor are
`coupled to a common processing system 313. System 313
`compares the response from the primary touch Screen with
`the false touch sensor. Thus if system 313 determines that a
`touch was observed by the primary Sensor but was not
`Verified by the Secondary or false touch Sensor, the touch is
`nullified. For example in system 300, if a drop of water hits
`screen 301, the SAW or infrared primary sensor would
`indicate a touch. This touch, however, would not be verified
`by the false touch Sensor as the water drop is ungrounded.
`Similarly, in system 400 where the primary sensor employs
`non-overlay differential force technology, a physical shock
`to the CRT would register a touch, but this touch would not
`be verified because there would be no grounding of the
`secondary sensor. In either system 300 or 400, if processor
`313 determines that a touch was registered by both the
`primary Sensor and the false touch Sensor, the touch is
`validated.
`It should be understood that although the examples pro
`vided above assume that a valid touch is one in which the
`false touch Sensor is touched by a grounded object, e.g., a
`finger, a valid touch can also be defined as one in which the
`detected Signal amplitude is less than a preset threshold. For
`example, in a medical laboratory it may be desirable to
`require lab technicians to wear rubber gloves, thereby mini
`mizing the risk of contamination. Using the present
`invention, the false touch Sensor can be designed to invali
`date any touch in which the detected Signal amplitude
`exceeds the preset threshold, thus indicating that the user is
`not wearing rubber gloves. Therefore in this application of
`the invention, the absence of a Signal indicating that the
`detected Signal amplitude has exceeded the preset threshold
`validates the touch from the primary touch Sensor.
`In another embodiment similar to that shown in FIGS. 3
`and 4, as opposed to relying on the charge limiting coating
`on a CRT Screen as the Secondary Sensor, a Screen overlay
`is used. In this embodiment, capacitive touch technology, as
`illustrated in FIG. 5, forms the basis of the secondary sensor.
`AS in the previous embodiments, the primary Sensor can
`utilize SAW sensors, infrared sensors, or differential force
`Sensors. The differential force Sensors, however, can either
`be overlay or non-overlay force Sensors.
`FIG. 5 is a cross-sectional view of a capacitive touch
`sensor, Such as that disclosed in U.S. Pat. No. 5,457,289, the
`disclosure of which is incorporated herein for all purposes.
`An overlay Substrate 501 is used that can be incorporated
`into a CRT or other touch panel. A transparent conductive
`coating 503 (e.g., ITO coating) is deposited onto Substrate
`501 with a protective overlay coating 505 (e.g., SiO,
`coating). Transparent conductive coating 503 can either be
`excited by electromagnetic noise, as in the resistive coating
`of CRT screen 301, or by an external frequency source 507.
`AS in the embodiment illustrated in FIGS. 3 and 4, this
`embodiment utilizing an overlay capacitive Sensor as the
`Secondary sensor is coupled to processor 313 (not shown)
`via discriminator 311 (not shown) and monitor 305 (shown).
`The monitoring/discriminator System then determines
`
`Petitioners Samsung and Sony Ex-1006, 0014
`
`

`

`7
`whether or not a touch received by the primary Sensor is
`valid, i.e., due to a grounded signal from a finger or
`equivalent object. Therefore, as in the previous embodiment,
`a touch due to a contaminant received by a SAW or infrared
`primary Sensor, or a shock to a System utilizing a force-based
`primary Sensor, will not be reported to the operating System
`Since the capacitive Secondary Sensor would not detect a
`corresponding touch by an ungrounded object.
`In this embodiment of the invention, the capacitive Sec
`ondary Sensor can either provide simple touch validation,
`Similar to that provided by the charge limiting resistive
`coating described in reference to FIGS. 3 and 4, or it can
`provide touch coordinates that can be compared by proces
`Sor 313 with the coordinates determined by the primary
`Sensor. In the latter case, the capacitive Secondary Sensor is
`fabricated using well known techniques, Such as those
`disclosed in U.S. Pat. No. 5,457,289.
`In another embodiment of the invention, force Sensors are
`used as the Secondary Sensor. Techniques for fabricating
`force sensors are well known by those of skill in the art and
`are typified by a temperature compensated Strain gauge Such
`as that disclosed in U.S. Pat. No. 5,742,222.
`As shown in FIG. 6, in the simplest configuration of this
`embodiment a single force Sensor 601 is located on a
`touchscreen 605. In the case of a single force Sensor,
`low-stiffness supports at corners 606 and a high-stiffness
`support at corner 608 may be used to avoid zones of limited
`or no touch sensitivity. Preferably sensor 601 is located just
`outside of the viewing region of screen 605 and underneath
`a touchscreen cowling 607. Alternately, four force sensors
`601-604 may be used, one located at each corner of touch
`Screen 605, to provide touch coordinates in a manner Similar
`to that disclosed in U.S. Pat. No. 5,708.460, the disclosure
`of which is incorporated herein for all purposes.
`In this embodiment of the invention, the force sensor is
`the Secondary Sensor while the primary Sensor is either an
`overlay utilizing a SAW sensor as illustrated in FIG. 7 or a
`capacitive touch sensor as illustrated in FIG. 8. In both
`FIGS. 7 and 8 multiple force sensors 60–604 are shown
`although it is understood that a single force sensor 601 could
`be used to provide touch validation. Therefore as shown in
`FIGS. 7 and 8, the output of sensor 601 can either be coupled
`to monitor 305 and discriminator 311 to provide touch
`validation or directly coupled to processor 313 along with
`the outputs from force sensors 602-604 to provide second
`ary touch coordinate determination.
`As shown in FIG. 7, the primary sensor includes trans
`mitter transducers 701, receiver transducers 703, and reflec
`tive grids 705. The capacitive primary sensor shown in FIG.
`8 includes a conductive coating 801 on screen 605 as well
`as electrode assemblies 803. If a contaminant causes the
`primary Sensor of FIG. 7 to detect an apparent touch, or if
`an inadvertent grounding causes t