Source: http://www.google.ca/patents/US8259078
Timestamp: 2017-11-19 14:23:41
Document Index: 69064066

Matched Legal Cases: ['art.\n1', 'Application No. 11159164', 'Application No. 11159166', 'Application No. 10178661', 'Application No. 11159165', 'Application No. 11159167']

Patent US8259078 - Touch screen liquid crystal display - Google Patents
Disclosed herein are liquid-crystal display (LCD) touch screens that integrate the touch sensing elements with the display circuitry. The integration may take a variety of forms. Touch sensing elements can be completely implemented within the LCD stackup but outside the not between the color filter plate...http://www.google.ca/patents/US8259078?utm_source=gb-gplus-sharePatent US8259078 - Touch screen liquid crystal display
Publication number US8259078 B2
Application number US 11/760,036
Also published as US8243027, US8552989, US20080062139, US20080062147, US20080062148
Publication number 11760036, 760036, US 8259078 B2, US 8259078B2, US-B2-8259078, US8259078 B2, US8259078B2
Inventors Steve Porter Hotelling, Wei Chen, Christoph Horst Krah, John Greer Elias, Wei Hsin Yao, John Z. Zhong, Andrew Bert Hodge, Brian Richards Land, Willem den Boer
Patent Citations (181), Non-Patent Citations (27), Referenced by (72), Classifications (12), Legal Events (3)
US 8259078 B2
1. An integrated liquid crystal display touch screen comprising:
a first substrate having display control circuitry formed thereon, the first substrate being disposed between the first polarizer and the second polarizer;
a second substrate disposed between the first polarizer and the second polarizer and adjacent the first substrate;
a plurality of touch sensing elements disposed between the first and second polarizers and not between the first and second substrates, the plurality of touch sensing elements comprising a plurality of touch drive electrodes and a plurality of touch sense electrodes, the plurality of touch drive electrodes and the plurality of touch sense electrodes being operative at least during a touch sensing mode of operation;
the plurality of touch drive electrodes and the plurality of touch sense electrodes spaced apart from one another to form capacitive coupling nodes therebetween;
a counter electrode used during a liquid crystal display operation and disposed between the liquid crystal layer and the second substrate, the counter electrode separate and distinct from the plurality of touch drive electrodes and separate and distinct from the plurality of touch sense electrodes;
the counter electrode being grounded during the touch sensing mode of operation to shield the plurality of touch drive electrodes and the plurality of touch sense electrodes disposed above the counter electrode, from the liquid crystal layer disposed below the counter electrode;
the plurality of touch drive electrodes operative to receive a periodic voltage;
the plurality of touch drive electrodes driven by the periodic voltage one at a time or in groups; and
at least one capacitance sensing circuit operatively coupled to the plurality of touch sense electrodes during the touch sensing mode of operation for measuring a change in current and/or voltage resulting from a change in capacitance at the capacitive coupling nodes.
3. The touch screen of claim 2 wherein the color filter is formed on a side of the second substrate facing the liquid crystal layer, and wherein the plurality of touch sensing elements are formed on the second substrate on a side opposite that of the color filter.
4. The touch screen of claim 3 wherein the plurality of touch sensing elements further comprise:
a first plurality of touch electrodes formed on the second substrate, the first plurality of touch electrodes being one of the plurality of touch drive or the plurality of touch sense electrodes;
a dielectric deposited over the first plurality of electrodes; and
a second plurality of touch electrodes formed on top of the dielectric, the second plurality of touch electrodes being the other of the plurality of touch drive or the plurality of touch sense electrodes.
5. The touch screen of claim 4 wherein the first plurality of touch electrodes formed on the second substrate comprises ITO patterned to form the plurality of touch drive electrodes or the plurality of touch sense electrodes.
6. The touch screen of claim 4 wherein the plurality of touch drive electrodes are driven by the periodic voltage one at a time or in groups while the non-driven touch drive electrodes are grounded.
7. The touch screen of claim 1 wherein the plurality of touch drive electrodes are driven by the periodic voltage one at a time or in groups while the non-driven touch drive electrodes are grounded.
8. The touch screen of claim 1 wherein the second substrate is glass.
9. The touch screen of claim 1 wherein the second substrate is plastic.
10. The touch screen of claim 1 wherein the plurality of touch sensing elements comprises a mutual capacitance touch-sensing arrangement.
wherein the first substrate further comprises touch control circuitry; and the touch screen further comprises an electrical connect r electrically connecting the touch control circuitry on the first substrate to the top surface of the second substrate.
12. The electronic device of claim 11, wherein the electrically connector comprises a flexible printed circuit.
13. The electronic d vice of claim 11 wherein the electrical connector comprises a first flexible printed circuit connecting the plurality of touch sense electrodes to the touch control circuitry and a second flexible printed, circuit connecting the plurality of touch drive electrodes to the touch control circuitry.
14. The touch screen of claim 1,
15. The touch screen of claim 14, wherein the electrically connector comprises a flexible printed circuit.
16. The touch screen of claim 14 wherein the electrical connector comprises a first flexible printed circuit connecting the plurality of touch sense electrodes to the touch control circuitry and a second flexible printed circuit connecting the plurality of touch drive electrodes to the touch control circuitry.
17. An electronic device incorporating an integrated liquid crystal display touch screen, wherein the liquid crystal display touch screen comprises:
at least one capacitance sensing, circuit operatively coupled to the plurality of touch sense electrodes during the touch sensing mode of operation for measuring a change in current and/or voltage resulting from a change in capacitance at the capacitive coupling nodes.
18. The electronic device of claim 17 wherein a color filter is formed on a side of the second substrate facing the liquid crystal layer, and wherein the plurality of touch sensing elements are formed on the second substrate on a side opposite that of the color filter.
wherein the plurality of touch drive electrodes are driven by the periodic voltage one at a time or in groups while the non-driven touch drive electrodes are grounded.
20. The electronic device of claim 19 wherein the plurality of touch sensing elements further comprise:
21. The electronic device of claim 20 wherein the electronic device comprises at least one of a handheld computer, a personal digital assistant, a media player, a mobile telephone, a desktop computer, a tablet computer, and a notebook computer.
22. The electronic device of claim 18 wherein the plurality of touch sensing elements further comprise:
23. The electronic device of claim 17 wherein the one or more touch sensors formed on the second substrate further comprise:
a first plurality of touch electrodes formed on the second substrate, the first plurality of touch electrodes being one of the plurality of touch drive or touch sense electrodes;
a second plurality of touch electrodes formed on top of the dielectric, the second plurality of touch electrodes being the other of the 3.1urality of touch drive or touch sense electrodes.
24. The electronic device of claim 23 wherein the electronic device is selected from the group consisting of a desktop Computer, a tablet computer, and a notebook computer.
25. The electronic device of claim 23 wherein the electronic device comprises at least one of a handheld computer, a personal digital assistant, a media player, and a mobile telephone.
26. The electronic device of claim 23 wherein the first plurality of touch electrodes formed on the second substrate comprises ITO patterned to form the plurality of touch drive electrodes.
27. The electronic device of claim 26 wherein the electronic device is selected from the group consisting of a desktop computer, a tablet computer, and a notebook computer.
28. The electronic device of claim 26 wherein the electronic device comprises at least one of a handheld computer, a personal digital assistant, a media player, and a mobile telephone.
29. The electronic device of claim 23 wherein the first plurality of touch electrodes formed on the second substrate comprises ITO patterned to form the plurality of touch sense electrodes.
30. The electronic device of claim 29 wherein the electronic device is selected from the group consisting of a desktop computer, a tablet computer, and a notebook computer.
31. The electronic device of claim 29 wherein the electronic device comprises at least one of a handheld computer, a personal digital assistant, a media player, and a mobile telephone.
32. The electronic device of claim 17 wherein the plurality of touch drive electrodes are driven by the periodic, voltage one at a time or in groups while the non-driven touch drive electrodes are grounded.
33. The electronic device of claim 32 wherein the electronic device is selected from the group consisting of a desktop computer, a tablet computer, a notebook computer, a handheld computer, a personal digital assistant, a media player, and a mobile telephone.
34. A mobile telephone incorporating an integrated liquid crystal display touch screen, wherein the liquid crystal display touch screen comprises:
a first substrate having display control circuitry formed thereon, the first substrate being disposed between the first polarizer an the second polarizer;
a plurality of touch sensing elements disposed between the first and second polarizers and not between the first and second substrates, the plurality of touch sensing elements comprising a plurality of touch drive electrodes and plurality of touch sense electrodes, the plurality of touch drive electrodes and the plurality of touch sense electrodes being operative at least during a touch sensing mode of operation;
at least one capacitance sensing circuit operatively coupled to the plurality of touch sense electrodes during the touch sensing m de of operation for measuring a change in current and/or voltage resulting from a change in capacitance at the capacitive coupling nodes.
35. The mobile telephone of claim 34 wherein the color filter is formed on a side of the second substrate facing the liquid crystal layer, and wherein the plurality of touch sensing elements are formed on he second substrate on a side opposite that of the color filter.
36. The mobile telephone of claim 34 wherein the plurality of touch sensing elements further comprise: a first st plurality of touch electrodes formed on the second substrate, the first plurality of touch el ctrodes being one of the plurality of touch drive or the plurality of touch sense electrodes;
37. The mobile telephone of claim 34 wherein the plurality of touch drive electrodes are driven by the periodic voltage one at a time or in groups while the non-driven touch drive electrodes are grounded.
This application claims priority to Provisional U.S. Patent Application Ser. No. 60/804,361, filed Jun. 9, 2006, and Provisional U.S. Patent Application Ser. No. 60/883,979, filed Jan. 8, 2007 which are both hereby incorporated by reference in their entirety.
This application is related to the following publications, incorporated by reference herein:
U.S. Patent Publication No.: 2006/0197753, titled “Multi-Functional Hand-Held Device,” published Sep. 7, 2006.
U.S. Patent Publication No.: 2006/0097991, titled “Multipoint Touch Screen,” published May 11, 2006, and issued as U.S. Pat. No. 7,663,607, issued on Feb. 16, 2010.
U.S. Patent Publication No.: 2007/0257890, titled “Multipoint Touch Screen Controller,” published on Nov. 8, 2007;
U.S. Patent Publication No.: 2008/0158181, entitled “Double-Sided Touch Sensitive Panel and Flex Circuit Bonding,” published Jul. 3, 2008and issued as U.S. Pat. No. 8,026,903, issued on Sep. 27, 2011.
U.S. Patent Publication No.: 2008/0062139, entitled “Touch Screen Liquid Crystal Display, published Mar. 13, 2008.
U.S. Patent Publication No.: 2008/0062148, entitled “Touch Screen Liquid Crystal Display, published Mar. 13, 2008.
U.S. Patent Publication No. 2008/0062140, entitled “Touch Screen Liquid Crystal Display, published Mar. 13, 2001.
According to one embodiment of the invention, an integrated liquid crystal display touch screen is provided. The touch screen can include a plurality of layers including a first polarizer, a first substrate having display control circuitry formed thereon (e.g., a TFT plate or array plate), a second substrate (e.g., a color filter plate) adjacent to the first, and a second polarizer. The touch screen can further include at least one touch sensing element disposed between the first polarizer and the second polarizer and not between the substrates. The touch sensing element can include one or more touch sensors formed on the second substrate.
The touch sensors can include, a first plurality of touch electrodes formed on the second substrate, a dielectric deposited over the first plurality of electrodes, and a second plurality of touch electrodes formed on top of the dielectric. The touch and drive electrodes can be formed from patterned indium-tin oxide (ITO). The touch sensors can also comprise active circuitry, including, for example, thin film transistors (TFTs). The substrates may be either glass or plastic. The touch electrodes may be part of a mutual capacitance or a self-capacitance arrangement.
In another embodiment, an electronic device incorporating an integrated LCD touch screen is provided. The electronic device can take the form of a desktop computer, a tablet computer, and a notebook computer. The electronic device can also take the form of a handheld computer, a personal digital assistant, a media player, and a mobile telephone. In some embodiments, a device may include one or more of the foregoing, e.g., a mobile telephone and media player.
FIG. 26 illustrates a flexible printed circuit for use with various LCD embodiments described herein
FIG. 28 illustrates a Open Circuit VCST touch drive option.
FIG. 60 illustrates update and touch-scanning of a touch-screen LCD with three regions.
FIG. 61 illustrates an electrode layout for a touch-screen LCD.
As described in the applications incorporated by reference, a touch surface, and specifically, a multi-touch capable transparent touch surface can be formed from a series of layers. The series of layers can include at least one substrate, e.g., glass, which can have disposed thereon a plurality of touch sensitive electrodes. For example, a mutual capacitance arrangement can include a plurality of drive electrodes and a plurality of sense electrodes separated by a non-conducting layer, i.e., the glass. Capacitive coupling between the drive and sense electrodes can be affected by proximity of a conductive object (e.g., a user's finger). This change in capacitive coupling can be used to determine the location, shape, size, motion, identity, etc. of a particular touch. These parameters can then be interpreted to control operation of a computer or other electronic device. Self-capacitance arrangements, as described below, are also known to those skilled in the art.
1.1. Multi-Touch Sensing
In self-capacitance systems, the “self” capacitance of a sensing point is measured relative to some reference, e.g., ground. Sensing points 102 may be spatially separated electrodes. These electrodes can be coupled to driving circuitry 104 and sensing circuitry 103 by conductive traces 105 a (drive lines) and 105 b (sense lines). In some self-capacitance embodiments, a single conductive trace to each electrode may be used as both a drive and sense line.
In mutual capacitance systems, the “mutual” capacitance between a first electrode and a second electrode can be measured. In mutual capacitance sensing arrangements, the sensing points may be formed by the crossings of patterned conductors forming spatially separated lines. For example, driving lines 105 a may be formed on a first layer and sensing lines 105 b may be formed on a second layer 105 b such that the drive and sense lines cross or “intersect” one another at sensing points 102. The different layers may be different substrates, different sides of the same substrate, or the same side of a substrate with some dielectric separation. Because of separation between the drive and sense lines, there can be a capacitive coupling node at each “intersection.”
The arrangement of drive and sense lines can vary. For example, in a Cartesian coordinate system (as illustrated), the drive lines may be formed as horizontal rows, while the sense lines may be formed as vertical columns (or vice versa), thus forming a plurality of nodes that may be considered as having distinct x and y coordinates. Alternatively, in a polar coordinate system, the sense lines may be a plurality of concentric circles with the drive lines being radially extending lines (or vice versa), thus forming a plurality of nodes that may be considered as having distinct radius and angle coordinates. In either case, drive lines 105 a may be connected to drive circuit 104, and sensing lines 105 b may be connected to sensing circuit 103.
During operation, a drive signal (e.g., a periodic voltage) can be applied to each drive line 105 a. When driven, the charge impressed on drive line 105 a can capacitively couple to the intersecting sense lines 105 b through nodes 102. This can cause a detectable, measurable current and/or voltage in sense lines 105 b. The relationship between the drive signal and the signal appearing on sense lines 105 b can be a function of the capacitance coupling the drive and sense lines, which, as noted above, may be affected by an object in proximity to node 102. Capacitance sensing circuit (or circuits) 103 may sense sensing lines 105 b and may determine the capacitance at each node as described in greater detail below.
As discussed above, drive lines 105 a can be driven one at a time, while the other drive lines are grounded. This process can be repeated for each drive line 105 a until all the drive lines have been driven, and a touch image (based on capacitance) can be built from the sensed results. Once all the lines 105 a have been driven, the sequence can repeat to build a series of touch images. However, in some embodiments of the present invention, multiple drive lines may be driven substantially simultaneously or nearly simultaneously, as described in U.S. patent application Ser. No. 11/619,466, titled “Simultaneous Sensing Arrangement,” filed Jan. 3, 2007.
FIG. 3 illustrates a simplified schematic diagram of mutual capacitance circuit 300 corresponding to the arrangement described above. Mutual capacitance circuit 300 may include drive line 105 a and sense line 105 b, which can be spatially separated thereby forming capacitive coupling node 102. Drive line 105 a may be electrically (i.e., conductively) coupled to drive circuit 104 represented by voltage source 301. Sense line 105 b may be electrically coupled to capacitive sensing circuit 103. Both drive line 105 a and sense line 105 b may, in some cases, include some parasitic capacitance 302.
As noted above, in the absence of a conductive object proximate the intersection of drive line 105 a and sense line 105 b, the capacitive coupling at node 102 can stay fairly constant. However, if an electrically conductive object (e.g., a user's finger, stylus, etc.) comes in proximity to node 102, the capacitive coupling (i.e., the capacitance of the local system) changes. The change in capacitive coupling changes the current (and/or voltage) carried by sense line 105 b. Capacitance sensing circuit 103 may note the capacitance change and the position of node 102 and report this information in some form to processor 106 (FIG. 1).
In some embodiments, sensing circuit 103 may include one or more microcontrollers, each of which may monitor one or more sensing points 102. The microcontrollers may be application specific integrated circuits (ASICs) that work with firmware to monitor the signals from touch sensitive surface 101, process the monitored signals, and report this information to processor 106. The microcontrollers may also be digital signal processors (DSPs). In some embodiments, sensing circuit 103 may include one or more sensor ICs that measure the capacitance in each sensing line 105 b and report measured values to processor 106 or to a host controller (not shown) in computer system 107. Any number of sensor ICs may be used. For example, a sensor IC may be used for all lines, or multiple sensor ICs may be used for a single line or group of lines.
1.2. Transflective LCDs
1.2.1. Circuit Basics
FIG. 5 shows a representative layout for an LTPS transflective subpixel 500. Display information can be transferred to the subpixel's capacitors CST and CLC (not shown) when a voltage representing the desired grey level is applied to the data bus 501 and the select line 502 is asserted. The select line 502 assertion level can be near the gate drive positive supply voltage. During the time when select line 502 is asserted, the voltage on VCST (and VCOM, which is not shown) can be constant. All the circuit elements shown in FIG. 5, which includes metal, poly, active, oxide, and ITO, can be fabricated on the LCD's bottom glass.
Each display row can include horizontal traces for VCST 606 and select (not shown). The select traces connect to gate drive circuitry made up of poly-silicon thin film transistors (p-Si TFTs), also not shown. The VCST traces 606 can run from display edge to display edge and can connect together, e.g., as shown on the left. The VCST traces can also connect, through a conductive dot 607, to an ITO plane 609 on the top glass 610. Typically, four conductive dots, one in each corner, can be used to connect the VCOM plane to VCOMDrive 611. FIG. 6 shows only one dot 607 for simplicity. The voltage of VCST and top glass ITO 609 can be set by VCOMDrive, which can be provided by the LCD driver IC (not shown). VCST can also be connected to another drive source other than VCOMDrive 611.
FIG. 7 illustrates a circuit diagram 700 for a subpixel and shows on which glass substrate various components can be fabricated. The bottom glass 701 can be the substrate for the integration of all the TFT pixel circuitry 703. This can include the select line drivers and control logic. The bottom glass can also serve as the substrate for chip on glass (COG) components, such as the LCD driver (not shown). The upper electrode 704 of capacitor CLC can be on the top glass 702. Electrode 704 can be an ITO plane that covers the entire display area and forms the counter electrode to the bottom electrode 705 making CLC. Upper electrode 704 can also connect, e.g., through four corner-located conductive dots 706 (only one shown), to VCOMDrive 707 on bottom glass 701.
VCOMDrive requirements can be fairly simple: its voltage can remain constant until the charge transfer has completed for a row of pixels, thus setting their grey levels. Once the display pixels are set, VCOMDrive can change without significantly affecting the LC state provided that parasitic pathways into and out of the subpixel remain small.
1.3. LCD Manufacturing
1.4. Combining LCDs and Touch Sensing
One embodiment of the present invention, Concept C, uses the stackup illustrated in FIG. 13, which allows the touch function to be separate from the LCD. In Concept C, two additional indium-tin oxide (ITO) layers (ITO1 1301 and ITO2 1302) can be patterned on top of the color filter (CF) plate (e.g., the top glass layer) These layers can be used for touch sense and touch drive elements of a touch sensor, e.g., a mutual-capacitance touch sensor. These ITO layers can be patterned into columns and/or rows (as shown in FIGS. 1 and 2, and described in the preceding multi-touch sensing description), and can be separated by a dielectric 1305, such as a glass substrate or a thin (e.g., 5-12 mm) SiO2 layer.
FIG. 16 illustrates a self-capacitance touch pixel circuit for Concept N. Each ITO touch pixel 1612 can be connected to two TFTs, e.g., an input TFT 1604 and an output TFT 1608. The input TFT 1604 can charge ITO touch pixel 1612, while output TFT 1608 can discharge ITO touch pixel 1612. The amount of charge moved can depend on the ITO touch pixel's 1612 capacitance, which can be altered by the proximity of a finger. Further details of self-capacitance touch-sensing are described above and in U.S. Pat. No. 6,323,846, titled “Method and Apparatus for Integrating Manual Input,” issued Nov. 27, 2001, which is hereby incorporated by reference in its entirety.
In one embodiment, an output column 1610 can be shared by touch pixels vertically, and output gates 1606 can be shared by touch pixels horizontally, as shown in FIGS. 16 and 18 for output column 1610 ‘C0’ and output gates 1606 ‘R3’. FIG. 19 shows a detailed layout of a touch pixel.
2.2. Partially-Integrated Touch-Sensing
The touch sensor electrode array can include two layers of patterned ITO as illustrated in FIG. 21 (left side). FIG. 21 is a simplified view of one possible implementation of touch sensor electrodes. The layer closer to the viewer, ITO1 2101, can be the touch output layer also called the sense layer or the sense lines. The touch drive layer 2102 can be located on layer ITO2. ITO2 can also form the upper electrode of the capacitor CLC (see FIG. 7). FIG. 21 (right side) also shows a detail of three sense pixels 2103 a, 2103 b, and 2103 c along with associated capacitors. Both the sense and drive lines can have a 5 mm pitch with a 10 to 30 micron gap. The gap can be just small enough to be invisible to the naked eye, but still large enough to be easy to etch with a simple proximity mask. (Gaps in the figure are greatly exaggerated).
2.2.1.5. Concept A: Sharing Touch Drive with LCD VCOM
As discussed above, Concept A can add one layer of ITO to a standard LCD stackup, which can function as the touch sense lines. The touch drive layer can be shared with the LCD's VCOM plane, also denoted ITO2. For display operation, a standard video refresh rate (e.g., 60 fps) can be used. For touch sensing, a rate of at least 120 times per second can be used. However, the touch scanning rate can also be reduced to a slower rate, such as 60 scans per second, which can match the display refresh rate. In some embodiments, it may be desirable to not interrupt either display refresh or touch scanning. Therefore, a scheme that can allow the sharing of the ITO2 layer without slowing down or interrupting display refresh or touch scanning (which can be taking place at the same or different rates) will now be described.
Because display scanning typically proceeds in line order, touch drive segments can be driven out of sequential order to prevent an overlap of display and touch activity. In the example shown in FIG. 27, the touch drive order was 1, 2, 3, 4, 0 during the first 8.3 msec and 1, 2, 4, 3, 0 in the second 8.3 msec period. The actual ordering can vary depending on the number of touch drive segments and the number of display rows. Therefore, in general, the ability to program the order of touch drive usage may be desirable. However, for certain special cases, a fixed sequence ordering may be sufficient.
2.2.1.6. Concept A: VCST Drive Options
As illustrated in FIG. 7, VCST and VCOM can be connected together and can thus be modulated together to achieve the desired AC waveform across the LC. This can help achieve proper display refresh when using VCOM modulation. When VCOM is used for touch drive, it is not necessary to also modulate VCST. This can be considered as the Open Circuit VCST Option, described below. However, if VCST is modulated with VSTM, the capacitive load on the touch drive signal, VSTM, can be reduced, which can lead to a smaller phase delay in the touch signal. This can be considered as the Drive VCST Option, described below.
The capacitive load on Concept A's touch drive line can be high, for example, because of the thin (e.g., ˜4 μm) gap between the touch drive layer and the bottom glass, which can be covered by a mesh of metal routes and pixel ITO. The liquid crystals can have a rather high maximum dielectric constant (e.g., around 10).
2.2.1.8. Concept A: Electrical Model and VCOM-Induced Noise
Concept A60 can be physically similar to Concept A and can provide a different approach to the problem of synchronizing display updates and touch scanning. This can be accomplished by using the I-line inversion of VCOM as the stimulus for the touch signal (i.e., VSTM). This is illustrated in FIG. 33, which shows how a single touch drive segment 3301 can be modulated while other touch drive segments can be held at a constant voltage. With this approach, the problem of removing the unwanted VCOM-induced noise from the touch signal can be eliminated. Furthermore, it is not necessary to spatially separate display updating and touch sensor scanning. However, using this approach, demodulation can be done at a single frequency (i.e., the VCOM modulation frequency, e.g., ˜14.4 kHz) as opposed to the multi-frequency demodulation described in U.S. patent application Ser. No. 11/381,313, titled “Multipoint Touch Screen Controller,” filed May 2, 2006, incorporated by reference herein. Furthermore, using this approach, the touch sensor scan rate can be fixed at the video refresh rate (e.g., 60 per second).
2.2.3.2. Concept B: Conductive Dots
As with Concept A, the capacitive load on Concept B's touch drive line can be high. The large capacitance can be due to the thin (e.g., ˜5 μm) dielectric between touch drive (ITO2) 3402 and VCOM plane (ITO3) 3403. One way to reduce undesirable phase delay in the touch stimulus signal can be to lower the ITO drive line resistance through the addition of parallel metal traces. Phase delay can also be reduced by decreasing the output resistance of the level shifter/decoder.
2.2.3.6. Concept B: Electrical Model and VCOM-Induced Noise
ITO3 (e.g., the LCD's VCOM layer), which can have a sheet resistance between 30 and 100 ohms/square, can also be applied (block 3505) using conventional methods. However, as discussed above, VCOM voltage distortion can be reduced by reducing the resistance of the ITO3 layer. If necessary, lower effective resistance for ITO3 can be achieved by adding metal traces that run parallel to the touch drive segments. The metal traces can be aligned with the black matrix so as to not interfere with the pixel openings. The density of metal traces can be adjusted (between one per display row to about every 32 display rows) to provide the desired resistance of the VCOM layer.
2.2.4. Concept B′
2.2.6. Concept X′
2.3. Fully-Integrated Touch-Sensing
2.3.1. Fully-Integrated VCOM-Based LCDs
2.3.1.1. Concept A′
Concept X is illustrated in FIGS. 45 and 46. The stack-up for Concept X, shown in FIG. 45, can be basically identical to that of a standard LCD. Touch sense layer 4501 can be embedded within the VCOM layer (ITO2), which can serve the dual purpose of providing the VCOM voltage plane and acting as the output of the touch sensor. The touch drive layer can also be embedded within an existing LCD layer. For example, touch drive can be located on bottom glass 4503 and can be part of the LCD select line circuitry (see FIG. 5). The select circuit can thus serve a dual purpose of providing gate signals for the subpixel TFTs and the touch drive signal VSTM. FIG. 46 is a top view of Concept X showing one possible arrangement of the touch sense layer with its floating pixels 4601 embedded in the VCOM layer.
2.3.1.3. Concept H
For touch sensing, switches 4702 can be operated as follows. The north and south switches can be used to measure the Y-direction capacitance. The left and right side switches can be used to measure the X-direction capacitance. The switches at the northeast and southwest corners can be used for both X and Y measurement. Capacitance can be measured by stimulating resistive sheet 4701 with a modulation waveform VMOD, illustrated in FIG. 49. The current (i.e., charge) required to drive the sheet to the desired voltage can be measured and used to determine the location of the touch.
2.3.1.6. Concepts M1 and M2
FIGS. 59,60, and 61 show an exemplary display (corresponding to Concept M2) that has been segmented into three regions (5901, 5902, 5903; FIG. 59), and wherein two regions can be simultaneously touch-scanned (e.g., regions 5901, 5902) while a third region's display pixels can be updated (e.g., region 5903). On the left side of FIG. 61, twenty seven vertical drive lines 6101 in the ITO1 and M1 (metal 1) layers can provide three different regions with nine touch columns each. Each drive line (3 per touch column) can have a conductive dot (not shown) down to the array glass, and can be routed to a driver ASIC.
The right side of FIG. 61 shows the possible modes for the segmented horizontal rows of the ITO2 layer, which include VCOM and VHOLD for a first set of alternating rows 6102 and VCOM, VHOLD, and VSENSE for a second set of alternating rows 6103. Each ITO2 row can connect via a conductive dot (not shown) down to the array glass, from which the mode of the row can be switched using LTPS TFT switches. The right side of FIG. 61 shows twenty-one sense rows, of which fourteen can be sensed at any time (although other numbers of rows could also be more).
FIG. 62 shows the circuit diagram for touch sensing in the exemplary display illustrated in FIGS. 59, 60, and 61. VSTM driver 6200 sends a signal through metal drive column 6202, which can have a resistance of Rmetcol and a parasitic capacitance of Cdrv. Touch capacitance Csig can be measured across the ITO row, which can have a resistance of Rito2row and a parasitic capacitance of Cito2row. The touch-sensing charge can also be affected by two additional resistances, Rsw1 and Rborder, before reaching charge amplifier 6204.
FIG. 63 shows a display in which the display regions can be scanned and updated horizontally instead of vertically (as in FIG. 60). The touch drive and touch sense regions can be interleaved so that a stimulus applied to touch drive row 6301 can be simultaneously sensed from two sense rows 6302 and 6303, as indicated by sense field lines 6305.
The black mask layer can be used to hide metal wires and/or gaps in ITO layers. For example, the metal drive lines, etched gaps in ITO2, and etched gaps in ITO1 can be fully or partially hidden behind the black mask (as shown in FIG. 64). This can reduce or eliminate the visual impact these items may have on the display's user.
2.3.1.8. Concepts P1 and P2
FIG. 72 shows a stackup diagram for Concept P1. Concept P1 can differ from a standard LCD process in various respects. For example, a portion of the standard polymer black mask can be changed to black chrome with low-resistance metal backing. These conductive lines can then be used to route signals to and from the touch pixels. A layer of patterned ITO 7202 can be added behind the black mask in an additional mask step. STN-style conductive dots 7203 can be added to route the drive and sense signals for each touch pixel to the LTPS TFT plate (e.g., using 2 dots per touch pixel). The color filter layer and the bordering planarization layer 7204 can also be thickened to decrease the capacitance between the touch drive and VCOM.
Another embodiment, Concept D, can support multi-touch sensing using two segmented ITO layers and an additional transistor for each touch pixel. FIG. 77 shows a circuit diagram for Concept D. During display updates, the circuit can function as in a standard LCD display. Gate drive 7700 can drive two transistors (Q1 7702 and Q2 7704), thereby allowing signals from VCOM bus 7706 and data lines 7708 to transfer charge to a set of capacitors controlling the LC (CST 7710, CLC1 7712, and CLC2 7714). When transistor Q2 7704 is turned off VCOM 7706 is disconnected from CST 7710, allowing VCOM line 7706 to be used for touch sensing. Specifically, VCOM line 7706 can be used to send charge through CIN 7716 and COUT 7718, through the data line 7708 (which acts as a touch sense line) into charge amplifier 7720. A conductive object (such as a user's finger, stylus, etc.) approaching the display can perturb the capacitances of the system in a manner that can be measured by the charge amplifier 7720.
Because IPS displays lack a VCOM layer that can also be used for touch drive or touch sense, some embodiments of the present invention can provide touch-sensing capabilities by allowing the same electrodes used for display updating to also be used for touch sensing. These electrodes can be complimented by additional circuitry. In some embodiments discussed above, touch pixels can overlap a large number of display pixels. In contrast, because the IPS embodiments discussed below can use the same electrodes used for display control and touch sensing, higher touch resolution can be obtained with little to no additional cost. Alternatively, a number of touch pixels can be grouped to produce a combined touch signal with a lower resolution.
2.3.2.1. Concept E
3.1. DITO
3.2. Replacing Patterned ITO with Metal
Various embodiments can eliminate the patterned ITO layer that forms touch sense electrodes and replace this layer with very then metal lines deposited on one of the layers, for example, on the top glass. This can have a number of advantages, including eliminating an ITO processing step. Additionally, the sense line electrodes may be made quite thin (e.g., on the order of 10 microns), so that they do not interfere with visual perception of the display. This reduction in line thickness can also reduce the parasitic capacitance which can enhance various aspects of touch screen operation, as described above. Finally, because the light from the display does not pass through a layer substantially covered with ITO, color and transmissivity can be improved.
3.3. Use of Plastic for Touch Sense Substrate
3.4. Level Shifter/Decoder Integration with LCD Controller
In one approach, a discrete level shifter/decoder COG can be attached to the bottom glass (see FIG. 22). In this arrangement metal traces may be needed in the peripheral area. The number of traces can depend on the number of touch drive segments, which may be less than twenty for small displays. Design objectives of this approach can include reducing capacitive coupling, which can be affected by the spacing between touch drive traces, and the space between the touch drive traces and other LCD circuits in the peripheral area. Low trace impedance can also help reduce capacitive coupling between adjacent touch drive traces.
Level shifter/
decoder Output Metal Trace Conductive Dot ITO Segment
FIG. 99 shows a simplified diagram of the level shifter/decoder COG 9901 for Concept A. (For Concept B, transistor Q1 and ENB_LCD[x] decoder can be eliminated.) Registered decoder block 9902 can be comprised of three separate registered decoders, which can be loaded one at a time. One of the three decoders can be selected by two signals from the Touch/LCD Driver and can be programmed using 5-bit data. The decoder outputs can control the three transistors Q1, Q2, Q3 associated with each output section of the level shifter/decoder. Each output section can be in one of three states: 1) LCD (Q1 on, Q2 and Q3 off), 2) touch (Q2 on, Q1 and Q3 off), or 3) GND (Q3 on, Q1 and Q2 off). As mentioned above, Q2's output resistance can be approximately 10 ohms or less to reduce VSTM phase delay. For Concept B, the LCD decoder and Q1 can be eliminated.
FIG. 101 shows a simplified block diagram of the fully integrated Touch/LCD driver 10101, which can include the boost circuitry 10102 to generate VSTM. Passive components (such as capacitors, diodes, and inductors) may also needed, but, as with all the other approaches, have not been shown for simplicity.
The multiple touch events can be used separately or together to perform singular or multiple actions in the host device. When used separately, a first touch event may be used to perform a first action while a second touch event may be used to perform a second action that can be different than the first action. The actions may, for example, include moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device etc. When used together, first and second touch events may be used for performing one particular action. The particular action may for example include logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user's preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like.
Display device 10308 can also include an integral touch screen 10309 (shown separately for clarity, but actually integral with the display) that can be operatively coupled to the processor 10302. Touch screen 10309 can be configured to receive input from a user's touch and to send this information to processor 10302. Touch screen 10309 can recognize touches and the position, shape, size, etc. of touches on its surface. Touch screen 10309 can report the touches to processor 10302, and processor 10302 can interpret the touches in accordance with its programming. For example, processor 10302 may initiate a task in accordance with a particular touch.
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Cooperative Classification G06F2203/04103, G06F3/044, G02F1/13338, G06F3/0412, G06F2203/04112
European Classification G02F1/1333U, G06F3/044, G06F3/041D
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HOTELLING, STEVE PORTER;CHEN, WEI;KRAH, CHRISTOPH HORST;AND OTHERS;REEL/FRAME:020157/0844;SIGNING DATES FROM 20071024 TO 20071118
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HOTELLING, STEVE PORTER;CHEN, WEI;KRAH, CHRISTOPH HORST;AND OTHERS;SIGNING DATES FROM 20071024 TO 20071118;REEL/FRAME:020157/0844