`
`US008599150B2
`
`(IO) Patent No.: US 8,599,150 B2
`
`c12) United States Patent
`
`(45)Date of Patent:
`Dec. 3, 2013
`
`
`Philipp
`
`(54)TOUCHSCREEN ELECTRODE
`
`CONFIGURATION
`
`
`
`(75) Inventor: Harald Philipp, Ramble (GB)
`
`
`
`10/2011 Hamblin
`
`8,031,174 B2
`10/2011 Hotelling
`
`8,040,326 B2
`11/2011 Hotelling
`
`8,049,732 B2
`5/2012 Frey
`
`8,179,381 B2
`5/2012 Sakashita
`8,179,384 B2
`7/2012 Chang
`
`8,217,902 B2
`12/2002 Itoh
`
`2002/0186210 Al
`5/2008 Wang
`
`2008/0117186 Al
`12/2008 Matsuo
`2008/0309635 Al
`( *) Notice: Subject to any disclaimer, the term ofthis
`
`
`
`6/2009 Jiang
`2009/0153502 Al
`7/2009 Silk et al. ...................... 345/173
`
`
`2009/0184940 Al *
`
`
`
`patent is extended or adjusted under 35
`
`
`9/2009 Geaghan et al. .............. 345/173
`2009/0219258 Al *
`
`
`U.S.C. 154(b) by 276 days.
`11/2009 Chen et al. .................... 345/174
`2009/0273577 Al*
`12/2009 Matsuo
`2009/0315854 Al
`2/2010 Geaghan ....................... 345/174
`
`
`2010/0026664 Al *
`(Continued)
`
`
`
`(73)Assignee: Atmel Corporation, San Jose, CA (US)
`
`
`
`(21)Appl. No.: 12/608,779
`
`
`
`(22)Filed:Oct. 29, 2009
`
`(65)
`
`
`
`Prior Publication Data
`
`FOREIGN PATENT DOCUMENTS
`
`
`
`US 2011/0102361 Al May 5, 2011
`
`(51)Int. Cl.
`G06F 3/041
`
`G06K 11106
`
`G0SC 21100
`
`G06F 3/045
`
`G06F 3/033
`
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`(2013.01)
`(2006.01)
`
`JP
`WO
`
`
`2008-145998 6/2008
`
`WO 2012/129247 9/2012
`
`OTHER PUBLICATIONS
`
`"2009----Conductive InkjetTechnology", [online]. [retrieved Apr. 20,
`
`
`
`
`
`
`
`2010]. Retrieved from the Internet: <URL: http://www.
`
`
`
`conductiveinkjet.com/about-us/latest-news/2009 .aspx>, 1 pg.
`
`(Continued)
`
`(56)
`
`
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`G06F 3/044
`(52)U.S. Cl.
`Primary Examiner - Alexander S Beck
`
`
`
`
`
`
`USPC ..................... 345/173; 178/18.01; 178/18.02;
`
`
`Assistant Examiner - Nguyen H Truong
`
`
`
`178/18.03; 178/18.05; 178/18.06; 178/19.03
`
`
`
`(74)Attorney, Agent, or Firm - Baker Botts LLP
`
`( 58)Field of Classification Search
`
`
`USPC ......... 345/173-178; 178/18.01-18.03, 18.05,
`(57)
`ABSTRACT
`
`178/18.06, 19.03
`A touchscreen includes touchscreen electrode elements dis
`
`
`
`
`
`
`
`See application file for complete search history.
`
`
`
`
`tributed across an active area of a substrate, and the touch
`
`
`
`
`screen overlays a display. The touchscreen electrode ele
`
`
`ments are configured to avoid creating moire patterns
`
`
`between the display and the touchscreen, such as angled,
`
`
`
`
`wavy, zig-zag, or randomized lines. In a further example, the
`
`
`7,663,607 B2 2/2010 Hotelling
`
`
`electrodes form a mesh pattern configured to avoid moire
`
`
`7,864,503 B2 1/2011 Chang
`
`
`7,875,814 B2 * 1/2011 Chen et al.
`178/18.07
`patterns.
`
`
`7,920,129 B2 4/2011 Hotelling
`
`8,031,094 B2 10/2011 Hotelling
`
`
`
`11 Claims, 7 Drawing Sheets
`
`
`
`riOO
`
`1�1\0
`
`�t\W1yy
`
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`
`2
`
`IPR2020-01000
`Apple EX1008 Page 1
`
`
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`US 8,599,150 B2
`
`Page 2
`
`(56)
`
`References Cited
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`U.S. PATENT DOCUMENTS
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`"New Silver Conductive Inks Target High-Growth Touch Screen and
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`OLED Markets", [ online]. [retrieved Apr. 20, 201 O]. Retrieved from
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`the Interent: <URL: http://www2.dupont.com/MCM/en_US/news_
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`
`events/article20100413.htrnl>, (Apr. 13, 2010), 3 pgs.
`2010/0028811 Al 2/2010 Geaghan
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`"Printing of Antennas and Flexible Circuits", Core Applications &
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`2010/0045614 Al* 2/2010 Gray et al. .................... 345/173
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`Technologies, (c) 2009 Conductive Inkjet Technology Ltd., (Oct.
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`2010/0079387 Al 4/2010 Rosenblatt
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`2009), 23 pgs.
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`2010/0328228 Al 12/2010 Elias
`Hiirteis, M., et al., "Fine Line Printed and Plated Contacts on High
`
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`2011/0032193 Al 2/2011 Szalkowski
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`OHMIC Emitters Enabling 20% Cell Efficiency", 2009 34th IEEE
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`
`2011/0095996 Al* 4/2011 Yilmaz ......................... 345/173
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`2012/0242588 Al 9/2012 Myers
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`Photovoltaic Specialists Conference (PVSC), (2009), 000060-
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`2012/0242592 Al 9/2012 Rothkopf
`000065.
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`2012/0243151 Al 9/2012 Lynch
`U.S. Appl. No. 13/288,385, filed Nov. 3, 2011, Yilmaz.
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`2012/0243719 Al 9/2012 Franklin
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`Office Action for U.S. Appl. No. 13/312,702, Mar. 16, 2012.
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`2013/0076612 Al 3/2013 Myers
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`U.S. Appl. No. 61/454,936, filed Mar. 21, 2011, Myers.
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`U.S. Appl. No. 61/454,950, filed Mar. 21, 2011, Lynch.
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`U.S. Appl. No. 61/454,894, filed Mar. 21, 2011, Rothkopf.
`"Cambrios Technologies Corporation Awarded Department of
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`
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`
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`Office Action for U.S. Appl. No. 13/408,762, May 9, 2012.
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`Defense Contract for Flexible Solar Cells", [online]. [retrieved Apr.
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`Office Action for U.S. Appl. No. 13/408,762, Sep. 7, 2012.
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`
`20, 2010]. Retrieved from the Internet: <URL: <http://www.
`
`* cited by examiner
`
`
`
`
`cambrios.com/200/DOD_Release.htm>, (Apr. 12, 2010), 2 pgs.
`
`OTHER PUBLICATIONS
`
`IPR2020-01000
`Apple EX1008 Page 2
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`U.S. Patent Dec. 3, 2013 Sheet 1 of 7 US 8,599,150 B2
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`IPR2020-01000
`Apple EX1008 Page 5
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`U.S. Patent Dec. 3, 2013 Sheet 4 of 7 US 8,599,150 B2
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`·DRIVER
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`IPR2020-01000
`Apple EX1008 Page 6
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`U.S. Patent Dec. 3, 2013 Sheet 5 of 7 US 8,599,150 B2
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`Apple EX1008 Page 7
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`Apple EX1008 Page 8
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`U.S. Patent Dec. 3, 2013 Sheet 7 of 7 US 8,599,150 B2
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`IPR2020-01000
`Apple EX1008 Page 9
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`
`
`CONFIGURATION
`
`BACKGROUND
`
`SUMMARY
`
`US 8,599,150 B2
`
`1
`
`
`2
`FIG. 3 illustrates a two-layer touchscreen assembly com
`
`
`
`
`
`TOUCHSCREEN ELECTRODE
`
`
`
`
`prising randomized electrodes configured to reduce moire
`
`
`
`effect when overlaying a display, consistent with an example
`embodiment.
`FIG. 4 shows a two-layer touchscreen display assembly
`
`
`
`
`
`comprising overlapping drive and receive mesh electrode
`
`
`
`
`
`Touchscreen displays are able to detect a touch within the
`
`
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`
`
`patterns configured to reduce moire effect when overlaying a
`
`
`
`
`
`active or display area, such as detecting whether a finger is
`
`
`display, consistent with an example embodiment.
`
`
`
`present pressing a fixed-image touchscreen button or detect
`
`
`FIG. 5 shows a self capacitance touch sensing system,
`
`
`
`
`
`ing the presence and position of a finger on a larger touch
`
`10 consistent with an example embodiment.
`
`
`
`
`screen display. Some touchscreens can also detect the pres
`
`
`FIG. 6 shows a mutual capacitance touch sensing system
`
`
`
`ence of elements other than a finger, such as a stylus used to
`
`
`
`
`with a finger present, consistent with an example embodi
`
`
`
`
`generate a digital signature, select objects, or perform other
`ment.
`
`
`functions on a touchscreen display.
`FIG. 7 shows a single layer touchscreen assembly overlay-
`
`
`
`
`
`
`
`Use of a touchscreen as part of a display allows an elec
`
`
`15 ing a LCD display panel according to an example embodi
`
`
`
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`tronic device to change a display image, and to present dif
`ment.
`
`
`
`ferent buttons, images, or other regions that can be selected,
`FIG. 8 shows an exploded view of a dual layer touchscreen
`
`
`
`
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`manipulated, or actuated by touch. Touchscreens can there
`
`
`
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`assembly overlaying a LCD display panel according to an
`
`
`
`
`
`fore provide an effective user interface for cell phones, GPS
`
`example embodiment.
`
`
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`
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`devices, personal digital assistants (PDAs ), computers, ATM
`
`FIG. 9 shows the assembled dual layer touchscreen assem
`
`machines, and other devices.
`20
`
`
`bly of FIG. 8 according to an example embodiment.
`
`
`Touchscreens use various technologies to sense touch from
`
`
`
`FIG. 10 shows a cellular telephone having a touchscreen
`
`
`
`
`
`a finger or stylus, such as resistive, capacitive, infrared, and
`
`
`
`display according to an example embodiment.
`acoustic sensors. Resistive sensors rely on touch to cause two
`
`
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`
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`resistive elements overlaying the display to contact one
`DETAILED DESCRIPTION
`
`
`another completing a resistive circuit, while capacitive sen-25
`
`
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`
`
`sors rely on the capacitance of a finger changing the capaci
`Touchscreens are often used as interfaces on small elec
`
`
`
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`tance detected by an array of elements overlaying the display
`
`
`
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`
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`tronic devices, appliances, and other such electronic systems
`device. Infrared and acoustic touchscreens similarly rely on a
`
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`
`
`because the display behind the touchscreen can be easily
`finger or stylus to interrupt infrared or acoustic waves across
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`
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`varito the user and to receive to provide instruction the screen, indicating the presence and position of a touch. 30 adapted
`
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`
`
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`ous types of input, thereby providing an intuitive interface
`
`
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`Capacitive and resistive touchscreens often use transparent
`
`
`
`
`that requires very little user training to use effectively. Inex
`conductors such as indium tin oxide (ITO) or transparent
`
`
`
`
`
`pensive and efficient touchscreen technologies enable incor-
`conductive polymers such as PEDOT to form an array over
`
`
`
`
`
`poration of touchscreens into inexpensive commercial
`the display image, so that the display image can be seen
`
`
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`
`
`devices, but these inexpensive technologies should also desir
`
`through the conductive elements used to sense touch. The 35
`
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`
`
`ably be durable and have relatively high immunity to noise,
`
`
`size, shape, and pattern of circuitry have an effect on the
`
`
`moisture or dirt, or other unintended operation to ensure
`
`
`
`
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`accuracy of the touchscreen, as well as on the visibility of the
`
`
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`reliability and longevity of the touchscreen assembly.
`
`
`
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`circuitry overlaying the display. Although a single layer of
`
`In a typical mutual capacitance touchscreen, the capaci
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`most suitable conductive elements is difficult to see when
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`tance between drive electrodes and various receive or sense
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`overlaying a display, multiple layers can be visible to a user, 40
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`electrodes is monitored, and a change in mutual capacitance
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`
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`and some materials such as fine line metal elements are not
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`between the electrodes indicates the presence and position of
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`transparent but rely on their small size to avoid being seen by
`
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`
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`a finger. Mutual capacitance sensor circuitry measures the
`users.
`
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`capacitance between the drive electrodes and the receive elec-
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`Further, touchscreens are often used to overlay displays
`
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`overlay material that by a dielectric 45 trodes, which are covered
`
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`such as LCD display screens that have their own circuitry and
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`
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`provides a sealed housing. When a finger is present, field
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`
`
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`patterns. It is therefore desirable to consider the configu ration
`
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`
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`coupling between the drive and receive electrodes is attenu
`
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`of touchscreen electrode patterns when designing a touch-
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`
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`ated, as the human body conducts away a portion of the field
`screen.
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`that arcs between the drive and receive electrodes. This
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`50 reduces the measured capacitive coupling between the drive
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`
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`and receive electrodes. In a self-capacitance touchscreen, an
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`array of a single type of electrode is used to determine posi
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`A touchscreen includes touchscreen electrode elements
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`tion of a touch by monitoring the touch's influence on the
`
`
`
`
`distributed across an active area of a substrate, and the touch
`
`
`
`self-capacitance of each of the electrodes in the array. The
`
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`
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`screen overlays a display. The touchscreen electrode ele
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`
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`
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`55 attached circuitry can measure the self capacitance of a single
`
`
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`ments are configured to avoid creating moire patterns
`
`
`electrode, or of groups of electrodes such as rows and col
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`
`
`between the display and the touchscreen, such as angled,
`
`
`
`unms of electrodes. In a more detailed example, an amount of
`
`
`
`
`
`wavy, zig-zag, or randomized lines. In a further example, the
`
`
`
`charge needed to raise the voltage of the electrode by a pre
`
`electrodes form a mesh pattern configu red to avoid moire
`
`
`
`
`determined amount is measured, thereby determining the
`patterns.
`
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`60 capacitance of each electrode. When a finger is present, the
`BRIEF DESCRIPTION OF THE FIGURES
`
`
`
`
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`self-capacitance of the electrode is increased, resulting in a
`
`measurable change in self-capacitance.
`FIG. 1 shows a two-layer mutual capacitance touchscreen
`
`
`
`
`The touchscreen elements that overlay a display are occa
`
`
`assembly, consistent with the prior art.
`
`
`
`
`sionally formed from conductive materials such as metal wire
`
`
`
`
`FIG. 2 illustrates a variety of touchscreen element patterns
`
`
`
`
`65 traces or fine line metal, or more commonly conductors such
`
`
`
`
`designed to reduce moire effect when overlaying a display,
`
`
`as Indium tin oxide which are transparent and relatively con
`
`consistent with an example embodiment.
`
`
`
`ductive in thin layers. Other materials such as PEDOT (poly-
`
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`US 8,599,150 B2
`
`4
`3
`ethylene dioxythiophene) and other conductive polymers are
`
`
`
`
`The distribution of lines across the touchscreen display is
`
`
`
`
`
`also relatively transparent and used in some touchscreens.
`
`
`
`
`also generally uniform, resulting in relatively uniform bright
`
`
`An example touchscreen shown in FIG. 1 uses an array of
`
`
`
`
`ness across the touchscreen display. But, the regular pattern
`
`
`
`
`conductive traces as touchscreen elements, having X drive
`
`
`and spacing oflines such as in FIG. 1 can cause interference
`
`
`
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`and Y receive lines in different layers when operated in a
`
`
`
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`5 with the regular, repeating pixel pattern of a display, causing
`
`
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`mutual capacitance mode. In self-capacitance operation, the
`
`
`
`
`
`visible moire patterns that distort or reduce the clarity of an
`
`
`
`self capacitance of the X and Y electrodes are independently
`
`
`underlying displayed image.
`
`
`
`determined to determine the position of the finger in two
`relative to the line Configu ration of touchscreen elements
`
`
`
`
`
`
`
`dimensions. The elements in this example are distributed
`
`
`
`
`assembly is therefore of a display or pixel configu ration
`
`
`
`
`
`across the touchscreen display approximately evenly, and are
`
`
`
`
`10 important in some applications to reduce moire patterns, as
`
`
`divided into different zones 0-3 for both the X drive and Y
`
`
`
`
`line configurations that cover regular or repeating patterns of
`
`
`
`
`
`receive lines. In a more detailed mutual capacitance example,
`
`
`
`
`
`pixels can create interference or moire patterns in the touch
`
`
`
`four different drive signals XO-X3 drive the four separate
`
`
`
`
`screen display assembly. It is therefore desirable in some
`
`
`
`
`arrays of horizontal X drive lines, as shown generally at 101.
`
`
`
`
`embodiments to configure electrodes in an embodiment such
`
`
`The signals driving these lines capacitively couple with the
`
`
`
`that do not cause 15 as that of FIG. 1 to be irregu lar or at angles
`
`
`
`vertical receive lines YO-Y3, shown at 102. When a finger 103
`
`
`
`such interference with the underlying display assembly.
`
`
`
`
`
`touches the touchscreen, the finger desirably interacts with
`
`
`
`The line configuration in touchscreen displays in some
`
`
`
`several X drive lines, intersecting the XO and Xl drive lines
`
`
`
`
`example embodiments of the invention is determined to avoid
`
`
`
`
`such that the finger's position on the touchscreen can be
`
`
`
`creating interference or moire patterns as a result of the line
`
`
`
`
`determined by the degree ofinterference with capacitive cou
`
`
`
`
`
`20 geometry interacting with the pixel geometry of the display.
`
`
`
`pling of each drive and receive zone.
`
`
`
`For example, lines that are very near but slightly offset from
`
`
`
`In this example, the finger 103 interferes with capacitive
`
`
`a line angle of the display, such as one degree, are likely to
`
`
`
`coupling between the XO and Xl drive lines and the receive
`
`
`
`
`produce interference patterns. Similarly, right angles or frac
`
`
`
`
`lines approximately equally, and similarly interferes with the
`
`
`
`
`
`tions thereof such as 90 degree angles, 45 degree angles, and
`
`
`
`
`capacitive coupling between the Y2 and Y3 receive lines and
`
`
`
`
`25 22.5 degree angles may also be more likely to produce moire
`
`
`
`the X drive lines approximately equally. This indicates that
`
`
`
`
`patterns depending on the configuration of the display ele
`
`
`the finger's touch is located between XO and Xl, and between
`
`
`ments and the line pitch of the touchscreen element.
`
`Y2 and Y3 on the grid formed by the drive and receive lines.
`
`
`
`
`FIG. 2 shows several examples of touchscreen elements
`
`
`Although each zone in this example comprises multiple
`
`
`
`
`con-interference patterns, configu red to reduce or eliminate
`
`
`electrodes, in other examples each zone may have a single
`
`
`
`
`30 sistent with various example touchscreen embodiments.
`
`
`
`electrode, at the cost of a greater number of electrical con
`
`
`
`
`Touchscreen elements such as these can be substituted for the
`
`
`
`
`
`nections to the touchscreen. The touchscreen display of FIG.
`
`
`
`
`
`straight fine line metal elements of FIG. 1, reducing moire
`
`
`
`
`
`
`
`in a touchscreen assembly. pattern visibility 1 is here shown having four different vertical regions and four
`
`At 201, the lines are configu red at an angle rather than
`
`
`
`
`different horizontal regions, but other embodiments such as a
`
`
`
`
`
`
`
`
`
`and display assembly touchscreen to an edge of the square typical computer or smart phone application may have sig-35
`
`
`
`
`LCD display, reducing the likelihood ofinterference patterns.
`
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`nificantly more zones than shown in this example.
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`Because the finger touch 103 is somewhat round or oval in
`At 202, wavy lines are used to avoid long linear stretches of
`shape, it will interact more strongly with drive lines near the
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`fine metal line, reducing the probability of causing interfer
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`center of the finger than at either the top or bottom extreme
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`ence patterns. Similarly, the fine metal lines at 203 zig-zag,
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`edge of the fingerprint. Further, the finger will interact to a 40
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`breaking up long linear stretches of parallel lines. At 204, the
`lesser degree with adjacent drive and receive lines not directly
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`lines follow a randomized pattern, and so also lack long linear
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`under the area of physical contact between the finger and the
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`portions. A randomized electrode pattern is also shown at
`screen's protective layers, where the finger is still physically
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`205, but the randomized electrode line is shifted laterally
`near enough the drive and receive lines to interact with their
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`from line to line to break up vertical regularity in the electrode
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`45 pattern; the amount of shifting from line to line can in itself be
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`capacitive coupling.
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`The finger's influence on multiple drive and receive lines
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`randomized to further suppress the ability of groups oflines to
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`enables the touchscreen display to detect the vertical and
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`cause a moire effect. Fractal-based or other irregu lar shapes
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`horizontal position of a finger on the touchscreen display with
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`are used in further embodiments to achieve a similar effect.
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`very good accuracy, well beyond simply determining in
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`Although angled and wavy lines are used here to avoid
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`which of the four shown vertical and horizontal regions the 50
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`creating moire patterns, a variety of factors other than angle or
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`finger is located. To achieve this result, the line spacing here
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`direction of the lines will affect the likelihood of observing a
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`is configured anticipating a fingerprint that is approximately
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`moire pattern when overlaying a display with a touchscreen
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`8 mm in diameter. In this example, the lines are spaced
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`assembly, including touchscreen element or electrode line
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`approximately 2 mm apart, for a 6 mm electrode pitch, such
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`width, frequency, and scale. In some embodiments, the touch-
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`that a typical touch interacts strongly with at least three or
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`screen elements are formed using fine line metal on the order
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`four vertical and horizontal lines.
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`of 3-7 micrometers in width, which is much smaller than the
`In operation, a user of the touchscreen display 1 typical pixel size of even high resolution LCD displays. of FIG.
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`places a finger on or near the touchscreen as shown at 103. In
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`A high resolution LCD display pixel is typically made up
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`of three individual are sent via the red, green, and blue sub-pixels that are
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`mutual capacitance mode, series of pulses
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`XO-X4 drive lines, such that the mutual capacitance between 60 100-150 micrometers in diameter, or 0.1-0.15 millimeters.
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`the different X drive lines and Y receive lines can be sepaThis large difference in scale reduces the amount that a line
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`rately determined, such as by observation of a change in can overlap a pixel, limiting the amount the pixel's apparent
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`received charge or another suitable method. When the presbrightness can be attenuated by the overlapping touchscreen.
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`ence of a finger interrupts the field between the X and Y drive Because the difference between sub-pixels obscured by over-
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`and receive lines, such as by coming in close proximity to a 65 lapping touchscreen lines and sub-pixels not obscured by
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`portion of the touchscreen, a reduction in observed field coutouchscreen element lines is small, the chances of creating a
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`pling between the electrodes is observed.
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`visible moire pattern are greatly reduced. For example, a line
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`that is only 5 micrometers wide cannot substantially obscure
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`mean path, and other methods. FIG. 2 shows at 206 an
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`an LCD color sub-pixel that is 100 micrometers in diameter,
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`example of separately randomized electrode lines that are
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`resulting in little difference in visible brightness when the
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`constrained within a certain band or range.
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`touchscreen element line overlaps a sub-pixel of the underly
`In addition to line direction, spacing between lines and
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`ing display. Nevertheless, even a high pixel-to-line dimension
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`repetition of lines can also be varied to reduce the regularity
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`ratio touchscreen can exhibit subtle moire banding effects
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`of the fine line metal touchscreen element array, reducing the
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`under the right conditions, which might be objectionable.
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`chances for observing moire patterns. If the spacing between
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`The frequency or density of touchscreen lines is further a
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`lines is varied, whether with random lines such as fractal lines
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`factor in production of moire patterns, as greater spacing
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`or repeating lines such as wavy lines, the lines will be signifi
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`between lines or greater differences in pitch between over-
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`cantly less likely to form regular repeating patterns of obscur
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`lapping patterns generally tend to reduce likelihood of pro
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`ing pixels on an underlying display, reducing the chances of
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`ducing visible moire patterns. Returning to the example of
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`moire patterns being formed. As with randomizing line direc
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`FIG. 1, the example fingerprint 103 of approximately 8 mm
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`tion, variation in line spacing can be achieved using a number
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`covers approximately four lines, resulting in a line pitch of
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`of suitable techniques including randomization within a
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`approximately 2 mm between each line. When using fine line 15
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`range, normalization of random numbers to a desired range,
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`metal touchscreen element electrodes that are 5 micrometers
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`and other methods. Use ofline constraints such as boundaries
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`in width, the distance between lines is approximately 400
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`is again important in randomizing line spacing to ensure that
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`times the width of the lines, resulting in a very low line
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`adjacent lines, such as the X drive lines and Y receive lines of
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`density and a relatively large width from line to line. Both the
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`FIG. 1, do not come too close or touch one another, thereby
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`low density and relatively large spacing between lines reduce 20
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`causing field nonlinearities. FIG. 2 shows at 207 one such
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`the likelihood of producing visible moire patterns when over
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`example having variation of line position within a channel,
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`pixel configulaying a display having a regu larly repeating
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`and variation in frequency ofrepetition ofline features.
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`ration. In other examples, the line spacing is at least 20, 50,
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`FIG. 3 shows a two-layer touchscreen display assembly
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`100, or 150 times greater than the line width.
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`having randomized touchscreen element paths, such as is
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`The wavy and zig-zag lines in the examples shown include
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`shown at 204 of FIG. 2. In this example, a first set of touch
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`some repetition in configuration of the lines, such as repeat
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`screen elements 301 follow varying randomized paths so as to
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`edly going up and down in the same pattern. The degree of
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`not form regular patterns of overlap with the pixels of an
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`repetition between adjacent lines is varied in a further
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`underlying display. Similarly, a second set of touchscreen
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`example, to further reduce the chances of creating regu lar,
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`elements 302 also follow varying randomized paths to avoid
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`repeating patterns that can contribute to moire effects. A 30
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`creating moire patterns with the underlying display's pixels.
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`group of line elements such as 10, 20, 50, or some other
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`The lines 301 and 302 form a two-layer mutual capacitance
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`suitable number oflines is repeated in some embodiments to
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`touchscreen array of drive and receive electrodes in a further
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`form larger touchscreens, reducing the work needed to lay out
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`example embodiment, much like the example of FIG. 1, but
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`larger touchscreens having large numbers of touchscreen
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`with significantly improved immunity to creation of moire
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`electrode elements. Repetition of randomized lines can be 35
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`patterns. In an alternate embodiment, the array of lines 301
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`used where the repeated lines are sufficiently far apart or have
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`and 302 form a self-capacitance touchscreen array, in which
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`a sufficient number of non-repeating intervening lines as to be
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`the self capacitance of the lines 301 and 302 are used to
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`unlikely to contribute to moire patterns, such as repeating
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`determine the position of a touch on the two-dimensional
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`every 10 or 20 lines. A use a standard design er can therefore
`touchscreen
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`block of20 random lines and repeatedly use the same 20 lines 40
`As shown in the above examples, use of touchscreen elec
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`to produce a large touchscreen element array such as in FIG.
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`trode elements having complex or irregular patterns, irregular
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`1, avoiding the need to manually generate a large number of
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`spacing, and other variations can reduce moire effect when
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`random lines for each application.
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`the touchscreen overlays a display assembly having a regular
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`In some further examples, the scale of the line pattern is
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`repeating pattern of pixel elements. The examples of FIG. 2
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`also taken into consideration, such that the scale of repetition
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`can be easily applied to various touchscreen embodiments,
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`of the pixels of the underlying display is on a much smaller
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`such as the mutual capacitance and self capacitance touch
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`scale than the repetition of the anti-moire touchscreen ele
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`screen examples presented above, as well as other touch
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`ment pattern. For example, green sub-pixels on a touchscreen
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`screen embodiments such as single-layer touchscreens.
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`display may repeat every 100 microns, while the wavy line
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`FIG. 4 shows an arrangement of electrodes configured to
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`touchscreen electrode overlay repeats its pattern every 5 mil-50
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`form a touchscreen display, including overlapping mesh-like
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`limeters. This difference in scale greatly reduces the chances
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`arrays of electrodes. Here, a first array of electrodes 401 are
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`of observing a moire pattern, especially where the electrode
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`overlaid with a second array of electrodes 402, such that the
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`line size is small relative to the display's pixel size.
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`electrodes follow irregular paths configu red to avoid creating
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`In other examples, the lines are random or semi-random in
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`moire patterns when overlaying a display. Although the elec
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`path, such as fractal-type lines shown at 204. These lines can 55
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`trodes are formed on different layers here, similar arrange
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`be produced using a variety of methods including random
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`ments are used in other embodiments to form single layer
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`number generation, use of fractal algorithms, or can be drawn
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`touchscreen assemblies.
`by hand.
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`The touchscreen shown here can be operated configu ration
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`Because it is desirable to keep adjacent lines from overlap
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`in one example as a mutual capacitance touchscreen, such as
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`ping, and to know the approximate position of the line for
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`where the X lines are drive lines and the Y lines are receive
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`determining touch position, line position in a further embodi
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`lines. In another example, the X and Y lines are operated
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`ment is restricted to a certain band or range. This can be
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`independently as self-capacitance electrodes.
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`achieved in a number of ways, such as simply setting upper
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`In this example, the horizontal electrodes coupled to the Xl
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`and lower bounds for a randomization process, normalizing a
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`connection are shown within the area of region 403, and the
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`generated line to fit within a certain band, changing the prob-
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`vertical electrodes coupled to the Y2 connection are shown
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`ability of the next change in line direction based on line
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`within region 404. Region 405 similarly shows the vertical
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`position within a band to encourage reversion to a desired
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`electrodes coupled to connection Y3, and a section of the
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`touchscreen display that overlaps these drive and receive the intersections betweens-curves of the Y electrode pattern
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`are located in the open spaces formed by the polygons of the
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`segments is shown at 406. A "dead zone" of vertical elec
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`X electrode layer.
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`trodes not coupled to a vertical external connection are shown
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`at 407 ( denoted DZ), and are optionally included in various
`Further, the many crossovers between X electrodes and Y
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`electrode traces or wires when overlaid and viewed from
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`configurations in order to provide improved linearity. As 5
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`above are approximately orthogonal, reducing the change in
`electrode view at 408, the shown in the magn ified vertical
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`or sensitivity of the touchscreen to small alignm ent changes
`vertical dead zone Y electrode between the Y2 and Y3 receive
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`imperfections in the layer-to-layer assembly process.
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`electrode regions is broken up in the vertical direction to
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`Oblique angles can cause pattern displacement errors during
`prevent propagation of fields along the electrode axis, ensur
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`10 assembly which can cause substantial field non-linearities,
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`ing linear response of the touchscreen assembly.
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`and so it is desirable to reduce this form of error. In various
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`The magnified vertical Y electrode view at 408 also illus
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`further examples, the crossover angle between drive and
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`trates how the Y receive electrodes are formed in a mesh
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`receive elements is desirably at least 45 degrees, 60 degrees,
`having a continuous pattern of wavy lines that are intercon
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`or another suitable angle to manage the sensitivity of the
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`nected with wavy line segments, with breaks that separate the
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`15 touchscreen to pattern alignment.
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`Y2 and Y3 electrode zones from the dead zone (DZ) electrode
`Fine line patterns exhibit localized field fluctuations due to
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`407.These breaks are staggered here, to break up the regu
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`pattern granularity, which apart from layer to layer alignment
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`larity of separation between zones and prevent mo