Single-layer touch-sensitive display

ES 2 344 487 T3

DESCRIPTION

Single layer touch display device.

Field of the invention

This refers generally to input devices for computer systems, and more particularly to a mutual capacitance multi-touch sensor panel that can be fabricated on only one side of a substrate.

Background of the invention

Many types of input devices are currently available to perform operations on a computer system, such as buttons or keys, mice, trackballs, touch sensor panels, joysticks, touch screens, and the like. Touchscreens, in particular, are becoming increasingly popular due to their ease of use and versatility as well as their ever-decreasing price. Touch screens can include a touch sensor panel, which can be a transparent panel with a touch sensitive surface. The touch sensor panel may be positioned in front of a display screen so that the touch sensitive surface covers the visible area of ​​the display screen. Touchscreens can allow a user to make selections and move a cursor simply by touching the display screen with a finger or a pointer. In general, the touch screen can recognize the touch and the position of the touch on the display screen, and the computer system can interpret the touch and then perform an action based on the touch event.

Touch sensor panels can be implemented as a pixel array made up of multiple excitation lines (eg rows) crossing multiple sensing lines (eg columns), where the excitation and sensing lines are separated by a dielectric material. An example of such a touch sensor panel is described in US-A-2008/0158181 entitled "Double-Sided Touch Sensitive Panel and Flex Circuit Bonding", filed January 3, 2007. However, touch sensor panels that have sensing and excitation lines formed on the bottom side and the top side of a single substrate can be expensive to manufacture. One reason for that additional expense is that the thin film processing steps must be performed on both sides of the glass substrate, requiring protective measures for the processed side while the other side is being processed. Another reason is the cost of manufacturing the flexible circuit and the bond required to connect to both sides of the substrate.

Document US-B-6 188 391 discloses that by suitable use of a screen printed carbon ink patterning in combination with patterning of the solder mask layer on the upper (tactile) surface, a device is obtained. Compact capacitive touch pad pointer using only a two-layer plate as a substrate. The first layer, on the upper side of the printed circuit board, combines both the horizontal and vertical sensing electrode traces. The second layer, located on the underside of the printed circuit board, is formed in the conventional manner by coupling the controller chip and / or related circuitry.

Document US-A-2006/0097991 discloses a touch panel having a transparent capacitive sensing means configured to detect multiple touches or near touches that occur at the same time and at different positions in the plane of the touch panel and to generate different signals. Representative of the position of the touches on the plane of the touch panel for each of the multiple touches.

Summary of the invention

The invention is defined by the touch sensor panel according to claim 1, the method according to claim 18, the mobile phone according to claim 32 and the digital media player according to claim 33. Additional preferred embodiments are provided in the dependent claims.

This refers to a substantially transparent touch sensor panel featuring single-layer coplanar touch sensors fabricated on a single side of a substrate to detect single-touch or multi-touch events (the contact of one or multiple fingers or other objects on a touch-sensitive surface in different places at almost the same time). To avoid having to make substantially transparent detection and excitation lines on opposite sides of the same substrate, embodiments of the invention can form the detection and excitation lines on a single coplanar layer on the same side of the substrate. The excitation and detection lines can be manufactured as column-like patterns in a first orientation and as patches in a second orientation, where each column-like pattern of the first orientation is connected to a separate metallic trace in the border area. touch sensor panel, and all the patches in each of the multiple rows of the second orientation are connected to each other using a separate metallic trace (or other conductive material) in the edge area of ​​the touch sensor panel. The metallic traces in the edge areas can be formed on the same side of the substrate as the patches and columns, but separated from the patches and column-like patterns by a dielectric layer. The metallic traces can allow both patches and column-like patterns to be routed to the same short edge of the substrate so that a small flex circuit can be attached to a small area on only one side of the substrate.

ES 2 344 487 T3

Brief description of the drawings

FIG. 1a illustrates a partial view of an exemplary substantially transparent touch sensor panel featuring single layer coplanar touch sensors fabricated on a single side of a substrate in accordance with one embodiment of this invention.

FIG. 1b illustrates a partial view of an exemplary substantially transparent touch sensor panel including metallic traces running along the edge areas of the touch sensor panel in accordance with one embodiment of this invention.

Fig. 1c illustrates an exemplary connection of columns and row patches to metal traces in the edge area of ​​the touch sensor panel in accordance with one embodiment of this invention.

Fig. 2a illustrates an exemplary cross section of a touch sensor panel showing SITO traces and metallic traces connected through a pathway in a dielectric material in accordance with one embodiment of this invention.

Fig. 2b is an enlarged view of the exemplary cross-section shown in Fig. 2a in accordance with one embodiment of this invention.

FIG. 3 illustrates a top view of an exemplary column and adjacent row patches in accordance with one embodiment of this invention.

Fig. 4a is a graphical representation of a finger touch x coordinate versus observed mutual capacitance in a pixel for two adjacent pixels a-5 and b-5 in a single row exhibiting wide gaps.

Fig. 4b is a graphical representation of a finger touch x coordinate versus the mutual capacitance observed in a pixel for two adjacent pixels a-5 and b-5 in a single row exhibiting wide gaps, where spatial interpolation has been provided in accordance with one embodiment of this invention.

FIG. 4c illustrates a top view of an exemplary column and adjacent row patch pattern useful for greater pixel spacings in accordance with one embodiment of this invention.

FIG. 5 illustrates an exemplary STTO stack on a touch sensor panel substrate bonded to a shield glass in accordance with one embodiment of this invention.

FIG. 6 illustrates an exemplary computer system operable with a touch sensor panel in accordance with one embodiment of this invention.

FIG. 7a illustrates an exemplary mobile phone that may include a touch sensor panel and a computer system in accordance with one embodiment of this invention.

FIG. 7b illustrates an exemplary digital audio / video player that may include a touch sensor panel and a computer system in accordance with one embodiment of this invention.

Detailed description of the preferred embodiment

In the following description of preferred embodiments, reference is made to the accompanying drawings, which form a part thereof and which show, by way of illustration, specific embodiments in which the invention may be carried out. It should be understood that other embodiments can be used and that structural changes can be made without departing from the scope of the embodiments of this invention.

This refers to a substantially transparent touch sensor panel featuring single-layer coplanar touch sensors fabricated on a single side of a substrate to detect single-touch or multi-touch events (the contact of one or multiple fingers or other objects on a touch-sensitive surface in different places at almost the same time). To avoid having to make substantially transparent detection and excitation lines on opposite sides of the same substrate, embodiments of the invention can form the detection and excitation lines on a single coplanar layer on the same side of the substrate. The excitation and detection lines can be manufactured as column-like patterns in a first orientation and as patches in a second orientation, where each column-like pattern of the first orientation is connected to a separate metallic trace in the border area. touch sensor panel, and all the patches in each of the multiple rows of the second orientation are connected to each other using a separate metallic trace (or other conductive material) in the edge area of ​​the touch sensor panel. The metallic traces in the edge areas can be formed on the same side of the substrate as the patches and columns, but separated from the patches and column-like patterns by a dielectric layer. The metallic traces can allow both patches and column-like patterns to be routed to the same short edge of the substrate so that a small flex circuit can be attached to a small area on only one side of the substrate.

ES 2 344 487 T3

Although some embodiments of this invention may be described herein in terms of mutual capacitance multi-touch sensor panels, it should be understood that embodiments of this invention are not limited in that way, but may additionally apply to sensor panels of self-capacitance and one-touch sensor panels. Furthermore, although the touch panel sensors can be described herein in terms of an orthogonal array of touch sensors with rows and columns, embodiments of the invention are not limited to orthogonal arrays but can generally be applied to touch sensors arranged in any number of dimensions and orientations, including diagonal, concentric circle, three-dimensional and random orientations.

FIG. 1a illustrates a partial view of an exemplary substantially transparent touch sensor panel 100 featuring single layer coplanar touch sensors fabricated on a single side of a substrate in accordance with embodiments of the invention. In the example of Fig. 1a a touch sensor panel 100 is shown with eight columns (labeled a through h) and six rows (labeled 1 through 6), although it should be understood that any number of columns and rows can be used. Columns a through h may generally have a columnar shape, although in the example of Fig. 1a one side of each column includes stepped edges and notches designed to create separate sections in each column. Each of the rows 1 through 6 can be formed from a plurality of different patches or pads, each patch including a trace of the same material as the patch and routed to the edge area of ​​the touch sensor panel 100 to allow all patches of a particular row are connected to each other through metallic traces (not shown in Fig. 1a) that run along the edge areas. These metallic traces can be routed to a small area on one side of the touch sensor panel 100 and connected to a flexible circuit 102. As shown in the example of Fig. 1a, the patches that form the rows can be arranged in a configuration in generally pyramidal shape. In Fig. 1a, for example, the patches in rows 1-3 between columns a and b are arranged in an inverted pyramidal configuration, while the patches in rows 4-6 between columns a and b are arranged in an upright pyramidal configuration.

The columns and patches of Fig. 1a may be formed from a single coplanar layer of conductive material. In touch screen embodiments, the conductive material may be a substantially transparent material such as Single Layer Tin-Indium Oxide (SITO), although other materials may also be used. The SITO layer can be formed either on the back of a protective glass or on top of a separate substrate. Although reference may be made to SITO herein to simplify the description, it should be understood that other conductive materials may also be used in accordance with embodiments of the invention.

FIG. 1b illustrates a partial view of an exemplary substantially transparent touch sensor panel 100 that includes metallic traces 104 and 106 running along the edge areas of the touch sensor panel in accordance with embodiments of the invention. Note that the edge areas in Fig. 1b are enlarged for clarity. Each column ah may include a SITO trace 108 that allows the column to connect to a metallic trace via a pathway (not shown in Fig. 1b). One side of each column includes stepped edges 114 and notches 116 designed to create separate sections in each column. Each row 1-6 patch may include a SITO trace 110 that allows the patch to connect to a metallic trace via a pathway (not shown in Fig. 1b). SITO 110 traces can allow each patch in a particular row to self-connect to each other. Since metal traces 104 and 106 are formed in the same layer, they can all be routed to the same flex circuit 102.

If the touch sensor panel 100 is operated as a mutual capacitance touch sensor panel, either columns ah or rows 1-6 can be excited with one or more stimulation signals, and marginal effect electric field lines can be formed. between column areas and adjacent row patches. In Fig. 1b It should be understood that although only electric field lines 112 are shown between column a and row patch 1 (a-1) for illustrative purposes, the electric field lines may be formed between another column and adjacent row patches (for example, a-2, b-4, g-5, etc.) depending on which columns or rows are stimulated. Therefore, it should be understood that each row-column patch pair (e.g., a-1, a-2, b-4, g-5, etc.) can represent a two-electrode sensor or pixel in which the charge can be coupled to the sensing electrode from the excitation electrode. When a finger presses on one of these pixels, some of the marginal effect electric field lines that extend beyond the coating of the touch sensor panel are blocked by the finger, reducing the amount of charge coupled to the sensing electrode. This reduction in the amount of charge coupled can be detected as part of determining a resulting "image" of touch. It should be noted that in mutual capacitance touch sensor panel designs as shown in Fig. 1b, no separate reference ground is necessary, so that a second layer on the back side of the substrate or on a separate substrate is not necessary.

The touch sensor panel 100 can also be operated as a self-capacitance touch sensor panel. In such an embodiment, a reference ground plane can be formed on the back side of the substrate; on the same side as the patches and columns but separated from the patches and columns by a dielectric, or on a separate substrate. In a self-capacitance touch sensor panel, each pixel or sensor has a self-capacitance with respect to the reference ground that can be modified due to the presence of a finger. In self-capacitance embodiments, the self-capacitance of the columns ah can be independently detected, and the self-capacitance of rows 1-6 can also be independently detected.

Fig. 1c illustrates an exemplary connection of columns and row patches to metal traces in the edge area of ​​the touch sensor panel according to embodiments of the invention. Fig. 1c represents "Detail A" as shown in Fig. 1b, and shows column "a" and row patches 4-6 connected to metal traces 118 through

ES 2 344 487 T3 of SITO traces 108 and 110. As the SITO traces 108 and 110 are separated from the metallic traces 118 by a dielectric material, the vias 120 formed in the dielectric material allow the SITO traces to be connected to the metallic traces .

Fig. 2a illustrates an exemplary cross-section of a touch sensor panel 200 showing SITO traces 208 and metallic traces 218 connected through pathway 220 in a dielectric material 222 according to embodiments of the invention. Fig. 2a represents view BB as shown in Fig. 1c.

Fig. 2b is an enlarged view of the exemplary cross-section shown in Fig. 2a according to embodiments of the invention. Fig. 2b shows an exemplary embodiment in which SITO trace 208 exhibits a resistivity of approximately 155 ohms per square max. In one embodiment, dielectric 222 can be about 1500 angstroms of SiO₂ inorganic, which can be processed at a higher temperature and therefore allows the SITO layer to undergo a higher quality sputtering. In another embodiment, dielectric 222 can be about 3.0 microns of organic polymer. The 1500 angstroms of SiO₂ Inorganic can be used for touch sensor panels small enough that cross capacitance (between SITO trace 208 and metallic trace 218) is not a problem.

For larger touch sensor panels (having a diagonal dimension of 3.5 ”(8.9 cm) or more), cross capacitance can be a problem, creating an error signal that can only be partially compensated for. Therefore, for larger touch sensor panels a thicker dielectric layer 222 with a lower dielectric constant such as about 3.0 microns of organic polymer can be used to lower cross capacitance. However, using a thicker dielectric layer can cause the SITO layer to be sputtered at a lower temperature, resulting in lower optical quality and higher resistivity.

Referring again to the example of Fig. 1c, column edges 114 and row patches 4-6 can be staggered in the x dimension as space must be created for the SITO 110 traces connecting with row patches 4 and 5. (It should be understood that row 4 patch of the example of Fig. 1c is actually made up of two patches joined together). For optimal touch sensitivity, it may be desirable to balance the electrode area at pixels a-6, a-5, and a-4. However, if column "a" has been kept linear, row patch 6 may be thinner than row patch 5 or 4 and an imbalance would form between the electrodes of pixel a-6.

Fig. Illustrates a top view of a column and adjacent row patches by way of example according to embodiments of the invention, it may be generally desirable to make the mutual capacitance characteristics of pixels a-4, a-5 and a-6 are relatively constant to generate a relatively uniform z-direction touch sensitivity that remains within the range of the touch detection circuitry. Consequently, the areas to₄, to₅ and, column, should be almost the same as row patch areas 4, 5, and 6. To achieve this, section a₄ already₅ of column and row patch 4 can be reduced in the y direction compared to column section a6 and row patch 6 so that the area of ​​column segment a4 coincides with the area of ​​segments a₅ already₆ column. In other words, the pixel a₄-4 will be wider but shorter than pixel a₆-6, which will be narrower but longer.

From the figures mentioned above it should be apparent that the untreated spatial sensitivity can be distorted in some way. In other words. Since pixels or sensors may be slightly skewed or misaligned in the x direction, the x-coordinate of a touch event maximized at pixel a-6 (for example, a finger directly pressing pixel a-6), can be slightly different from the x coordinate of a tap event maximized at pixel a-4, for example. Accordingly, in embodiments of the invention, this misalignment can be undone in a computer algorithm to remap pixels and eliminate distortion.

Although a typical touch panel grid dimension may have pixels arranged on 5.0mm centers, a wider grid having about 6.0mm centers may be desirable, for example, to reduce the total number of electrical connections in touch sensor panel. However, expanding the sensor pattern can cause erroneous touch readings.

Fig. 4a is a graphical representation of a finger touch x coordinate versus observed mutual capacitance in a pixel for two adjacent pixels a-5 and b-5 in a single row with wide spacing. In Fig. 4a, graph 400 represents the mutual capacitance observed at pixel a-5 as the finger tap moves continuously from left to right, and graph 402 represents the mutual capacitance observed at pixel b-5 as the finger touch continuously scrolls from left to right. As expected, a drop in mutual capacitance 404 is observed at pixel a-5 when the finger touch passes directly over pixel a-5, and a similar drop in mutual capacitance 406 is observed at pixel b -5 when the finger touch passes directly over pixel b-5. If line 408 represents a threshold to detect a touch event, Fig. 4a illustrates that although the finger is never detached from the touch sensor panel surface, it may erroneously appear at 410 that the finger has momentarily detached from the surface. This position 410 may represent a point approximately midway between the two enlarged pixels.

Fig. 4b is a graphical representation of a finger touch x coordinate versus the mutual capacitance observed in a pixel for two adjacent pixels a-5 and b-5 in a single row with wide spacing, where the

ES 2 344 487 T3 spatial interpolation has been provided according to embodiments of the invention. As expected, a drop in mutual capacitance 404 is observed at pixel a-5 when the finger touch passes directly over pixel a-5, and a similar drop in mutual capacitance 406 is observed at pixel b -5 when the finger touch passes directly over pixel b-5. Note, however, that the increase and decrease of the mutual capacitance value occurs more gradually than in Fig. 4a. If line 408 represents a threshold to detect a touch event, Fig. 4b illustrates that as the finger moves from left to right over pixel a-5 and b-5, a touch event is always detected. in pixel a-5 or pixel b-5. In other words, this “blurring” of touch events is useful to avoid the appearance of false non-touch readings.

In one embodiment of the invention, the thickness of the protective glass of the touch sensor panel can be increased to create part or all of the spatial filtering or blurring shown in Fig. 4b.

FIG. 4c illustrates a top view of an exemplary column and adjacent row patch pattern useful for greater pixel spacings in accordance with embodiments of the invention. FIG. 4c illustrates an exemplary embodiment in which sawtooth electrode edges 412 are used in an elongated pixel in the x direction. The sawtooth electrode edges can allow the marginal effect electric field lines 414 to be present over a larger area in the x direction so that a touch event can be detected by the same pixel over a greater distance. in the x direction. It should be understood that the sawtooth configuration of Fig. 4c is provided by way of example only and other configurations such as serpentine edges and the like may also be used. These settings can further smooth the touch patterns and create additional interpolation and spatial filtering between adjacent pixels as shown in Fig. 4b.

FIG. 5 illustrates an exemplary SITO stack on a touch sensor panel substrate bonded to a shield glass in accordance with embodiments of the invention. The stack may include a touch sensor panel substrate 500, which may be made of glass, on which an anti-reflective (AR) film 510 may be formed, on one side, and on which an anti-reflective film (AR) 510 may be deposited and patterned, on the other side, metal 502 to form the bus lines in the edge areas. Metal 502 can have a resistivity of 0.8 ohms per square maximum. Then, an insulating layer 504 can be deposited on the substrate 500 and the metal 502. The insulating layer can be, for example, SiO₂ with a thickness of 1500 angstroms, or 3 microns of organic polymer. Photolithography can be used to form pathways 506 in insulator 504 and a conductive material 508 can subsequently be deposited and patterned on top of insulator and metal 502. The single layer of conductive material 508, which can be formed from a transparent conductive material such as ITO with a maximum resistivity of 155 ohms per square, can be more transparent than multilayer designs and can be easier to manufacture. A flex circuit 512 can be bonded to conductive material 508 and metal 502 using an adhesive 514 such as anisotropic conductive film (ACF). The entire subassembly can then be attached to protective glass 516 and a black mask 520 using an adhesive 518 such as pressure sensitive adhesive (PSA).

In an alternative embodiment, the metal, insulator and conductive material described above can be formed directly on the back side of the protective glass.

FIG. 6 illustrates an exemplary computer system 600 that can be operated with the touch sensor panel described above in accordance with embodiments of this invention. The touch screen 642, which may include a touch sensor panel 624 and a display device 640 (eg, an LCD module), may be connected to other components of the computer system 600 through connectors integrally formed on the touch sensor panel or using flexible circuits. Computer system 600 may include one or more panel processors 602 and peripherals 604, and panel subsystem 606. The processor (s) 602 may include, for example, ARM968 processors or other processors of similar functionality and capabilities. However, in other embodiments, the panel processor functionality may alternatively be implemented by dedicated logic, such as a state machine. Peripherals 604 may include, but are not limited to, random access memories (RAM) or other types of memory or storage, watchdog timers, and the like.

Panel subsystem 606 may include, but is not limited to, one or more analog channels 608, channel scan logic 610, and driver logic 614. Channel scan logic 610 can access RAM 612, can autonomously read analog channel data and control analog channels. This control may include multiplexing or otherwise connecting the sense lines of the touch sensor panel 624 to the analog channels 608. In addition, the channel scan logic 610 can control the driver logic and stimulation signals that are selectively applied to the drive lines of the touch sensor panel 624. In some embodiments, the panel subsystem 606, the panel processor 602 and peripherals 604 may be integrated into a single application-specific integrated circuit (ASIC).

The driver logic 614 can provide multiple outputs 616 from the panel subsystem and can feature a proprietary interface that drives the high voltage driver 618. The high voltage driver 618 can provide a level change from a low voltage level (e.g. , Complementary Metal Oxide Semiconductor (CMOS) levels down to a higher voltage level, providing a better signal-to-noise (S / N) ratio for noise reduction purposes. The outputs 616 of the panel subsystem can be routed to decoder 620 and level switch / driver 638, which can selectively connect one or more high voltage driver outputs to one or more drive line or row inputs 622 of panel through a proprietary interface and allow

ES 2 344 487 T3 the use of fewer high voltage driver circuits in the high voltage driver 618. Each panel row input 622 can drive one or more drive lines of the touch sensor panel 624. In some embodiments, high voltage driver 618 and decoder 620 can be integrated into a single ASIC. However, in other embodiments, the high-voltage driver 618 and decoder 620 can be integrated into the driver logic 614, and in still other embodiments, the high-voltage driver 618 and decoder 620 can be completely eliminated. .

The computer system 600 may also include a central processor 628 to receive outputs from the panel processor 602 and to perform actions based on the outputs that may include, but are not limited to, moving an object such as a cursor or pointer, providing vertical scrolling. or horizontally across the screen, adjust control settings, open a file or document, display a menu, make a selection, execute instructions, operate a peripheral device connected to the main device, answer a phone call, make a phone call, end a phone call, change the volume or audio settings, store information related to phone communications such as addresses, frequently dialed numbers, calls received calls, missed calls, log on to a computer or computer network, allow authorized persons to access restricted areas of the computer or computer network, upload a user profile associated with a preferred user disposition of the computer desktop, allow access to web content, run a particular program, encrypt or decode a message and / or the like. Central processor 628 may also perform additional functions that may not be related to panel processing and may be connected to program storage 632 and display device 640 such as an LCD to provide a user interface (UI) to a user. Of the device.

The touch sensor panel described above can be used to advantage in the system of Fig. 6 to provide a compact touch panel and UI that is cheaper, easier to build, and fits into existing mechanical control designs (the same physical coating).

Fig. 7a illustrates an exemplary mobile phone 736 that may include stacks of touch sensor panel 724 and display device 730 (optionally linked together using pSa 734) and the computer system described above according to embodiments of the invention. Fig. 7b illustrates exemplary digital audio / video player 740 which may include stacks of touch sensor panel 724 and display device 730 (optionally linked together using PSA 734) and the computer system described above according to embodiments of the invention. The mobile phone and digital audio / video player of Figs. 7a and 7b can advantageously benefit from the touch sensor panel described above as the touch sensor panel can allow these devices to be smaller and less expensive, which are important factors for the consumer that can have a significant effect on desirability. consumer and business success.

Although embodiments of this invention have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the embodiments of this invention as defined in the appended claims.