US20150242010A1

US20150242010A1 - Micro-wire electrode structure with single-layer dummy micro-wires

Info

Publication number: US20150242010A1
Application number: US14/191,482
Authority: US
Inventors: Ronald Steven Cok
Original assignee: Individual
Current assignee: Eastman Kodak Co
Priority date: 2013-09-20
Filing date: 2014-02-27
Publication date: 2015-08-27
Also published as: US9304636B2; US20150084907A1; US20150212613A1; US20150212537A1; TW201519050A; US20150242025A1; WO2015041878A1

Abstract

A micro-wire electrode structure includes a substrate having a surface. A plurality of first micro-wire electrodes spatially separated by first electrode gaps is located in a first layer in relation to the surface, each first micro-wire electrode including a plurality of electrically connected first micro-wires. A plurality of electrically isolated second micro-wire electrodes is located in a second layer in relation to the surface, the second layer at least partially different from the first layer. Each second micro-wire electrode includes a plurality of electrically connected second micro-wires. A plurality of first gap micro-wires is located in each first electrode gap, at least some of the first gap micro-wires located in a gap layer different from the first layer. The first gap micro-wires are electrically isolated from the first micro-wires.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly-assigned co-pending U.S. patent application Ser. No. ______ (Attorney Docket No. K001737US01RLO) filed concurrently herewith, entitled Making Micro-Wire Electrode Structure with Single-Layer Dummy Micro-Wires, by Cok the disclosure of which is incorporated herein.
Reference is made to commonly-assigned co-pending U.S. patent application Ser. No. 14/032,213, filed Sep. 20, 2013 entitled Micro-Wire Touch Screen with Unpatterned Conductive Layer, by Burberry et al.; and to commonly-assigned co-pending U.S. patent application Ser. No. 14/167,134, filed Jan. 29, 2014 entitled Micro-Wire Electrodes with Equi-Potential Dummy Micro-Wires, by Cok; the disclosures of which are incorporated herein.

FIELD OF THE INVENTION

The present invention relates to touch screens having micro-wire electrodes and an unpatterned transparent conductor layer.

BACKGROUND OF THE INVENTION

Transparent conductors are widely used in the flat-panel display industry to form electrodes that are used to electrically switch light-emitting or light-transmitting properties of a display pixel, for example in liquid crystal or organic light-emitting diode displays. Transparent conductive electrodes are also used in touch screens in conjunction with displays. In such applications, the transparency and conductivity of the transparent electrodes are important attributes. In general, it is desired that transparent conductors have a high transparency (for example, greater than 90% in the visible spectrum) and a low electrical resistivity (for example, less than 10 ohms/square).
Transparent conductive metal oxides are well known in the display and touch-screen industries and have a number of disadvantages, including limited transparency and conductivity and a tendency to crack under mechanical or environmental stress. Typical prior-art conductive electrode materials include conductive metal oxides such as indium tin oxide (ITO) or very thin layers of metal, for example, silver or aluminum or metal alloys including silver or aluminum. These materials are coated, for example, by sputtering or vapor deposition, and are patterned on display or touch-screen substrates, such as glass. For example, the use of transparent conductive oxides to form arrays of touch senses on one side of a substrate is taught in U.S. Patent Application Publication No. 2011/0099805 entitled “Method of Fabricating Capacitive Touch-Screen Panel”.
Transparent conductive metal oxides are increasingly expensive and relatively costly to deposit and pattern. Moreover, the substrate materials are limited by the electrode material deposition process (such as sputtering) and the current-carrying capacity of such electrodes is limited, thereby limiting the amount of power that is supplied to the pixel elements and the size of touch screens that employ such electrodes. Although thicker layers of metal oxides or metals increase conductivity, they also reduce the transparency of the electrodes.
Apparently transparent electrodes including very fine patterns of conductive elements, such as metal wires or conductive traces are known. For example, U.S. Patent Application Publication No. 2011/0007011 teaches a capacitive touch screen with a mesh electrode, as do U.S. Patent Application Publication No. 2010/0026664, U.S. Patent Application Publication No. 2010/0328248, and U.S. Pat. No. 8,179,381, which are hereby incorporated in their entirety by reference. As disclosed in U.S. Pat. No. 8,179,381, fine conductor patterns are made by one of several processes, including laser-cured masking, inkjet printing, gravure printing, micro-replication, and micro-contact printing. In particular, micro-replication is used to form micro-conductors formed in micro-replicated channels. The apparently transparent micro-wire electrodes include micro-wires between 0.5μ and 4μ wide and a transparency of between approximately 86% and 96%.
Conductive micro-wires are formed in micro-channels embossed in a substrate, for example as taught in CN102063951, which is hereby incorporated by reference in its entirety. As discussed in CN102063951, a pattern of micro-channels are formed in a substrate using an embossing technique. Embossing methods are generally known in the prior art and typically include coating a curable liquid, such as a polymer, onto a rigid substrate. A pattern of micro-channels is embossed (impressed or imprinted) onto the polymer layer by a master having an inverted pattern of structures formed on its surface. The polymer is then cured. A conductive ink is coated over the substrate and into the micro-channels, the excess conductive ink between micro-channels is removed, for example, by mechanical buffing, patterned chemical electrolysis, or patterned chemical corrosion. The conductive ink in the micro-channels is cured, for example, by heating. In an alternative method described in CN102063951, a photosensitive layer, chemical plating, or sputtering is used to pattern conductors, for example, using patterned radiation exposure or physical masks. Unwanted material (such as photosensitive resist) is removed, followed by electro-deposition of metallic ions in a bath.
Mutual capacitive touch screen devices are constructed by locating drive electrodes near sense electrodes to form an electric field. In one prior-art design, the drive and sense electrodes are located on a common substrate with bridge electrical connections to prevent electrical shorts between the drive and sense electrodes where the drive electrodes cross over or under the sense electrodes. In another prior-art design, the drive and sense electrodes are located on either side of a dielectric layer. Referring to FIG. 11, a prior-art display and touch-screen apparatus 100 includes a display 110 with a corresponding touch screen 120 mounted with the display 110 so that information displayed on the display 110 can be viewed through the touch screen 120. Graphic elements displayed on the display 110 are selected, indicated, or manipulated by touching a corresponding location on the touch screen 120. The touch screen 120 includes a first transparent substrate 122 with transparent first electrodes 130 extending in the x dimension on the first transparent substrate 122 and a second transparent substrate 126 with transparent second electrodes 132 extending in the y dimension facing the x-dimension transparent first electrodes 130 on the second transparent substrate 126. A dielectric layer 124 is located between the first and second transparent substrates 122, 126 and transparent first and second electrodes 130, 132. Touch pad areas 128 are formed by the overlap of the transparent first electrodes 130 with the transparent second electrodes 132. When a voltage is applied across the transparent first and second electrodes 130, 132, electric fields are formed between them that are measurable to detect changes in capacitance due to the presence of a touch element, such as a finger or stylus.
A display controller 142 connected through electrical bus connections 136 controls the display 110 in cooperation with a touch-screen controller 140. The touch-screen controller 140 is connected through electrical bus connections 136 and wires 134 and controls the touch screen 120. The touch-screen controller 140 detects touches on the touch screen 120 by sequentially electrically energizing and testing the apparently transparent x-dimension first and y-dimension second electrodes 130, 132.
Referring to FIG. 12 as well as FIG. 11, in another prior-art embodiment, the rectangular transparent first electrodes 130 separated by first electrode gaps 60 and transparent second electrodes 132 separated by second electrode gaps 62 include micro-wires 150 and are arranged orthogonally in a micro-pattern 156 on transparent first and second substrates 122, 126 with intervening dielectric layer 124, forming touch screen 120 which, in combination with the display 110 forms the touch screen 120 and display and touch screen apparatus 100.
As is known in the prior art, electromagnetic interference from the display 110 can interfere with the operation of the touch-screen 120. This problem is mitigated by providing a ground plane between the touch screen 120 and display 110. However, such a structure undesirably increases the thickness and decreases the transparency of the display and touch screen apparatus 100.
Alternatively, it has been recognized that shielding is achieved by controlling the relative width of the drive and sense electrodes. For example U.S. Pat. No. 7,920,129 discloses a multi-touch capacitive touch-sense panel created using a substrate with column and row traces formed on either side of the substrate. To shield the column (sense) traces from the effects of capacitive coupling from a modulated V_comlayer in an adjacent liquid crystal display (LCD) or any source of capacitive coupling, the row traces were widened to shield the column traces, and the row (drive) traces were placed closer to the LCD. In particular, the rows are widened so that there is spacing of about 30 microns between adjacent row traces. In this manner, the row traces can serve the dual functions of driving the touch sense panel, and also the function of shielding the more sensitive column (sense) traces from the effects of capacitive coupling.
Shielding has also been achieved by using metal micro-wire sense electrodes in combination with transparent conductive drive electrodes. For example U.S. Pat. No. 8,279,187 discloses a multi-layer touch panel having an upper electrode layer having a plurality of composite electrodes including a plurality of metal or metal alloy micro-wire conductors with a cross-sectional dimension of less than 10 microns, a lower electrode layer having a plurality of (patterned) indium oxide-based electrodes, the upper electrodes and lower electrodes defining an electrode matrix having nodes where the upper and lower electrodes cross over. The upper electrode layer is disposed between the first layer and the lower electrode layer and a dielectric layer is disposed between the upper electrode layer and the lower electrode layer. As noted above, it is difficult, expensive, or impossible to meet conductivity requirements for larger touch-screens using patterned indium tin oxide electrodes.
In general, touch screens are intended to be invisible to a user. It is important, therefore, that any conductive structures in a touch screen be visually imperceptible. In prior-art designs, apparently transparent conductive electrodes made of transparent conductive oxides reduce electrode visibility. Nonetheless, such electrodes do absorb some light, having a transparency for example of 88% in the visible range and a slightly yellow appearance. Thus, electrode structures in a touch screen having transparent conductive oxides are visible to perceptive users. In particular, regular first electrode gaps 60 between transparent first electrodes 130 and second electrode gaps 62 between transparent second electrodes 132 are visible as areas with increased transparency.
Referring to FIG. 13, to reduce the visibility of gaps between electrodes in a touch screen; dummy conductive structures are provided in the first electrode gap 60. These dummy structures typically include conductive materials and structures similar to those found in the electrodes but are not electrically connected to the electrodes. Thus, the dummy structures provide optical uniformity in the touch screen by providing structures with an appearance similar to the electrodes but without any electrical function. Micro-wire breaks 64 or other conductive element breaks between the dummy structures and the electrodes to maintain electrical isolation between the dummy structures and the electrodes are typically so small (for example, a few microns) that the micro-wire breaks 64 are imperceptible to viewers. As shown in FIG. 13, a plurality of rectangular, spatially separated transparent first electrodes 130 connected to wires 134 in an electrical bus connection 136 are arranged in an array on a first transparent substrate 122. Each transparent first electrode 130 includes a plurality of electrically connected micro-wires 150. Dummy micro-wires 152 located in first electrode gaps 60 between the transparent first electrodes 130 are arranged in a similar way so that the dummy micro-wires 152 located in the first electrode gaps 60 between the transparent first electrodes 130 appear similar to the micro-wires in transparent first electrodes 130.
U.S. Patent Application Publication No. 2011/0248953 entitled “Touch Screen Panel” describes conductive dummy patterns between adjacent sensing cells in a touch screen panel. U.S. Patent Application Publication No. 2011/0289771 entitled “Method for Producing Conductive Sheet and Method for Producing Touch Panel” describes unconnected dummy patterns formed near each side of a sensing region. U.S. Pat. No. 7,663,607 entitled “Multi-Point Touch Screen” describes dummy features disposed between driving lines and sensing lines to optically improve the visual appearance of the touch screen. The dummy features provide the touch screen with a more uniform appearance and are electrically isolated and positioned in the gaps between each of the lines. Although they can be patterned separately, the dummy features are typically patterned along with the lines and formed with the same conductive materials. The dummy features still produce some gaps but the gaps are much smaller than the gaps found between the lines.

SUMMARY OF THE INVENTION

There remains a need for further improvements in the structure of a display and touch-screen apparatus that improves sensitivity and efficiency, reduces susceptibility to electromagnetic interference, and improves optical uniformity.
In accordance with the present invention, a micro-wire electrode structure comprises:
a substrate having a surface;
a plurality of first micro-wire electrodes spatially separated by first electrode gaps located in a first layer in relation to the surface, each first micro-wire electrode including a plurality of electrically connected first micro-wires;
a plurality of electrically isolated second micro-wire electrodes located in a second layer in relation to the surface, the second layer at least partially different from the first layer and each second micro-wire electrode including a plurality of electrically connected second micro-wires; and a plurality of first gap micro-wires located in each first electrode gap, at least some of the first gap micro-wires located in a gap layer different from the first layer, the first gap micro-wires electrically isolated from the first micro-wires.
The present invention provides a micro-wire electrode structure useful in capacitive touch screens having improved sensitivity, efficiency, consistency, optical uniformity, and reduced susceptibility to electromagnetic interference. By locating dummy micro-wires from one layer in another layer, electrode electrical performance is improved and optical uniformity maintained or improved.
The presence of an unpatterned conductive layer electrically connected to first electrodes and first micro-wires provides electromagnetic shielding to the first and second electrodes, thereby reducing electromagnetic interference. The integrated unpatterned conductive layer therefore reduces device thickness by reducing the number of insulating layers. This has the additional benefit of reducing conductive layer thickness and improving transparency in comparison to a conventional shielding system.
The presence of the unpatterned conductive layer also increases capacitance between the first and second electrodes, thereby reducing the voltage needed to sense changes in the capacitive field, for example due to touches, thereby improving efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will become more apparent when taken in conjunction with the following description and drawings wherein identical reference numerals have been used to designate identical features that are common to the figures, and wherein:

FIGS. 1A, 1B, and 1C are plan views of different layers of a micro-wire electrode structure according to an embodiment of the present invention;

FIG. 1D is a perspective combining the layers of FIGS. 1A, 1B, and 1C;

FIGS. 2A, 2B and 2C are plan views of the same layer of a micro-wire electrode structure with different micro-wire markings according to another embodiment of the present invention;

FIG. 2C is a plan view of a layer of a micro-wire electrode structure according to another embodiment of the present invention;

FIG. 2D is a perspective combining the layers of FIGS. 2A, 2B, and 2C;

FIG. 3A is a plan view of a layer of a micro-wire electrode structure according to yet another embodiment of the present invention;

FIGS. 3B and 3C are plan views of the same layers of a micro-wire electrode structure with different micro-wire markings according to yet another embodiment of the present invention;

FIG. 3D is a plan view of a layer of a micro-wire electrode structure according to yet another embodiment of the present invention;

FIGS. 3E and 3F are perspectives combining the layers of FIGS. 3A, 3B, 3C and 3D, in different embodiments of the present invention;

FIGS. 4A and 4B are plan views of the same layer of a micro-wire electrode structure with different micro-wire markings according to a further embodiment of the present invention;

FIGS. 4C and 4D are plan views of different layers of a micro-wire electrode structure according to a further embodiment of the present invention;

FIGS. 5 and 6 are cross sectional views of different embodiments of the present invention;

FIGS. 7-10 are flow diagrams illustrating various methods of various embodiments of the present invention;

FIG. 11 is a prior-art perspective of a capacitive touch screen;

FIG. 12 is a plan view of two prior-art overlapping micro-wire electrodes useful in understanding the present invention;

FIG. 13 is a schematic illustrating prior-art micro-wire electrodes and dummy micro-wires useful in understanding the present invention; and

FIG. 14 is a cross sectional view of yet another embodiment of the present invention.

The Figures are not drawn to scale since the variation in size of various elements in the Figures is too great to permit depiction to scale.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a micro-wire electrode structure useful in forming capacitive touch-screen devices and in combination with a display. The micro-wire electrode structure improves electrode conductivity, optical uniformity, reduces the effects of electromagnetic interference, and improves touch-response sensitivity, efficiency, and consistency over the extent of the touch screen. The micro-wire electrode structure of the present invention is also useful in other applications requiring overlapping micro-wire electrodes and is not limited to applications of touch-screen devices. According to embodiments of the present invention, dummy wires provided for optical uniformity found in layers of conventional prior-art designs are instead used in different layers to improve electrode conductivity or resistance to electromagnetic interference.
FIGS. 1A, 1B, and 1C are plan views of layers forming a multi-layer structure. The layers are shown in combination in the perspective of FIG. 1D. Referring to FIG. 1D, a micro-wire electrode structure 5 includes a substrate 10 with first and second opposing sides, one of which provides a surface 12. In various embodiments, the substrate 10 is an element of a display 110, for example a cover or substrate of the display 110, or is affixed to the display 110. In an embodiment, the display 110 is a source of electromagnetic radiation located on or adjacent to the second opposing side.
As shown in FIGS. 1A and 1D, a plurality of electrically isolated first micro-wire electrodes 22 spatially separated by first electrode gaps 60 is located in a first layer 20 in relation to the surface 12. Each first micro-wire electrode 22 includes a plurality of electrically connected first micro-wires 24. The first electrode gaps 60 electrically isolate each of the first micro-wire electrodes 22 from the other first micro-wire electrodes 22 and each first micro-wire electrode 22 is connected to one of the wires 134 for controlling the first micro-wire electrode 22.
Referring to FIGS. 1B and 1D, a plurality of electrically isolated second micro-wire electrodes 52 is located in a second layer 50 in relation to the surface 12. The second layer 50 is at least partially different from the first layer 20. Each second micro-wire electrode 52 includes a plurality of electrically connected second micro-wires 54. Micro-wire breaks 64 electrically isolate each of the second micro-wire electrodes 52 from the other second micro-wire electrodes 52 and each second micro-wire electrode 52 is connected to one of the wires 134 for controlling the second micro-wire electrode 52.
Referring to FIGS. 1C and 1D, a plurality of first gap micro-wires 26 is located in each first electrode gap 60 in a gap layer 80 different from the first layer 20 (FIG. 1A). The first micro-wires 24 (FIG. 1A) and the first gap micro-wires 26 have the same pattern (ignoring the micro-wire breaks 64). The first gap micro-wires 26 are electrically isolated from the first micro-wires 24 in first micro-wire electrodes 22. In an embodiment, the first gap micro-wires 26 include micro-wire breaks 64, as described further below. In an embodiment, the first gap micro-wires 26 have the same micro-wire pattern over the touch-sensitive area 32 (FIGS. 1A-1C) as the first micro-wires 24 so as to provide a uniform optical appearance. In this embodiment, the first gap micro-wires 26 serve as dummy micro-wires to visually fill in the first electrode gaps 60 between the first micro-wire electrodes 22 and provide optical uniformity in the first electrode gaps 60.
As shown in FIGS. 1A, 1B, and 1C, the first and second micro-wire electrodes 22, 52 overlap in a touch-sensitive area 32. The overlapping portions of the first and second micro-wire electrodes 22, 52 form capacitors whose capacitance is detectably modified by the presence of a touching implement, such as a finger, to form a touch-screen device.
In an embodiment, the first and second micro-wires 24, 54 are formed in a regular micro-wire pattern that extends over the touch-sensitive area 32. In useful designs, the first electrode gaps 60 are readily visible to the unaided human visual system where the micro-wire breaks 64 are not when viewed at useful distances. For example, the first electrode gaps 60 are 10-1,000 microns wide and the micro-wire breaks 64 are 0.1-10 microns wide.
As shown in FIG. 1D with respect to the present invention, first gap micro-wires 26 that are described as located within the first electrode gap 60 are located within the first electrode gap 60 when viewed from a direction P perpendicular to the surface 12 so that the first gap micro-wires 26 appear between the first electrode gaps 60. The first electrode gap 60 extends through multiple layers in the direction P. As noted, the first gap micro-wires 26 are in a separate gap layer 80 that is different from the first layer 20 in the first electrode gap 60 but are not in the first layer 20. Thus, as shown in FIG. 1D, the first gap micro-wires 26 are located in the first electrode gaps 60 because, as viewed from the direction P perpendicular to the surface 12, the first gap micro-wires 26 appear between the first micro-wire electrodes 22. In further embodiments, the first micro-wire electrodes 22 extend in a first direction D1 parallel to the surface 12, the second micro-wire electrodes 52 extend in a second direction D2 parallel to the surface 12 and the first direction D1 is orthogonal to the second direction D2.
Referring to FIGS. 2A, 2B, 2C and 2D, in another embodiment of the present invention, the gap layer 80 is the second layer 50, the first gap micro-wires 26 are located within the second micro-wire electrodes 52, and at least some of the first gap micro-wires 26 are electrically connected to the second micro-wires 54. FIGS. 2A, 2B and 2C, are plan views of layers forming a multi-layer structure. The layers are shown in combination in the perspective of FIG. 2D.
As shown in FIG. 2D, the second layer 50 and the gap layer 80 are the same layer in relation to the surface 12 of the substrate 10 and display 110. The second layer 50 includes both the second micro-wires 54 and at least some of the first gap micro-wires 26 in second micro-wire electrodes 52. The second micro-wire electrodes 52 are electrically isolated from each other by the micro-wire breaks 64 in the first gap micro-wires 26, as illustrated in FIGS. 1A, 2A, 2B and 2C. The first micro-wire electrodes 22 with the first micro-wires 24 separated by first electrode gaps 60 are formed in a first layer 20 different from the second layer 50 and gap layer 80. The embodiment of FIGS. 2A, 2B, 2C and 2D provides an electrical advantage in that the second micro-wire electrodes 52 have improved electrical conductivity because the first gap micro-wires 26 are located within the second micro-wire electrodes 52 and are electrically connected to the second micro-wires 54, as shown in FIGS. 2A and 2B
FIG. 2A illustrates both the second micro-wire electrodes 52 and the first gap micro-wires 26 in the second layer 50 so that the second layer 50 is also the gap layer 80. The first gap micro-wires 26 are in the first electrode gap 60. The second micro-wires 54 of the second micro-wire electrodes 52 are shown with solid lines and the first gap micro-wires 26 are shown with dashed lines. Because the second layer 50 includes both the second micro-wires 54 and at least some of the first gap micro-wires 26, the second micro-wires 54 and at least some of the first gap micro-wires 26 are electrically connected to form second micro-wire electrodes 52 having a variable micro-wire density along the length of the second micro-wire electrodes 52. Note that the micro-wire breaks 64 illustrated in FIG. 1C in this embodiment electrically isolate each of the second micro-wire electrodes 52 from the other second micro-wire electrodes 52.
The elements and structures illustrated in FIG. 2B are identical to those of FIG. 2A. The only difference in the Figures is that the first gap micro-wires 26 are shown in FIG. 2B with solid lines as are the second micro-wires 54 of the second micro-wire electrodes 52 separated by the micro-wire breaks 64 in the first gap micro-wires 26 in the first electrode gap 60. Both the first gap micro-wires 26 and the second micro-wires 54 are in the second layer 50 (which is also the gap layer 80).
Referring next to the plan view of FIG. 2C, the first micro-wire electrodes 22 and the first micro-wires 24 separated by the first electrode gaps 60 are added to the illustration of FIG. 2B to illustrate the micro-wire electrode structure 5. The first micro-wires 24 of the first micro-wire electrodes 22 (illustrated in FIG. 1A) are shown with dashed lines to distinguish them from the second micro-wires 54 and the first gap micro-wires 26 of the second micro-wire electrodes 52. The first micro-wire electrodes 22 are separated by the first electrode gaps 60 and the second micro-wire electrodes 52 are separated by the micro-wire breaks 64 in the first gap micro-wires 26. Thus, in FIG. 2C, the micro-wires illustrated with solid lines are those of the second layer 50 and the micro-wires illustrated with the dashed lines are those of the first layer 20 (see also FIG. 2D). The first and second micro-wire electrodes 22, 52 overlap in the touch-sensitive area 32 to form capacitors useful in a capacitive touch screen.
As shown in FIG. 2C, the second micro-wire electrodes 52 are separated by the micro-wire breaks 64 in the first gap micro-wires 26 but otherwise have the same micro-wire pattern as the first micro-wires 24 and first gap micro-wires 26 (and the first micro-wire electrode 22) except that the second micro-wires 54 are spatially offset in one dimension in a direction parallel to the surface and are 180 degrees spatially out of phase with respect to the first micro-wires 24.
The embodiment of FIGS. 2A, 2B, 2C and 2D provides an electrical advantage in that the second micro-wire electrodes 52 have improved electrical conductivity because the first gap micro-wires 26 of the first electrode gap 60 are connected to the second micro-wires 54 of the second micro-wire electrodes 52 (FIG. 2B). Furthermore, the presence of additional first gap micro-wires 26 in the second micro-wire electrodes 52 reduces the interference of electromagnetic radiation arising from sources below the second layer 50 (e.g. the display 110) on the first micro-wire electrodes 22. Thus, if the first micro-wire electrodes 22 are used as sense electrodes and the second micro-wire electrodes 52 are used as drive electrodes in a capacitive touch screen, the sense electrode (first micro-wire electrodes 22) have reduced noise and interference and improved sensitivity.
FIGS. 1A, 1C, 3A, 3B, 3C and 3D are plan views of layers forming a multi-layer structure according to embodiments of the present invention. The layers are shown in different combinations in the perspectives of FIGS. 3E and 3F. As noted above, the second gap micro-wires 56 (FIGS. 3A-3D) are located in each second electrode gap 62 when viewed from a direction orthogonal to the surface 12 (FIG. 1D) and are not necessarily in a common layer with the second micro-wires 54 and second micro-wire electrodes 52.
Referring next to FIG. 3A, in another embodiment the second micro-wire electrodes 52 having the second micro-wires 54 are spatially separated by second electrode gaps 62. A plurality of second gap micro-wires 56 are located in each second electrode gap 62 and the second gap micro-wires 56 are electrically isolated from the second micro-wires 54 by the micro-wire breaks 64. The second gap micro-wires 56 have the same micro-pattern as the second micro-wires 54, ignoring the micro-wire breaks 64.
Referring next to FIG. 3B, the first gap micro-wires 26 illustrated in FIG. 1C are located in the second layer 50 of FIG. 3A, have a common micro-pattern with the second micro-wires 54 and second gap micro-wires 56, and at least some of the first gap micro-wires 26 are electrically connected to the second micro-wires 54. The first gap micro-wires 26 that are within the area defined by the second micro-wire electrodes 52 are electrically connected to the second micro-wires 54 of the second micro-wire electrode 52. The first gap micro-wires 26 that are not within the area defined by the second micro-wire electrodes 52 are not electrically connected to the second micro-wires 54 or the second micro-wire electrode 52. Instead, they are located in the second electrode gap 62 and, in an embodiment, are electrically connected to the second gap micro-wires 56.
In FIG. 3B, the second micro-wires 54 and the second gap micro-wires 56 are shown with solid lines. The first gap micro-wires 26 are shown with dashed lines. Because the first gap micro-wires 26 in the second electrodes 52 are electrically connected to the second micro-wires 54 they form a single electrode with variable micro-wire density. Likewise, because the first gap micro-wires 26 in the second electrode gap 62 are electrically connected to the second gap micro-wires 56, they form a single electrically conductive structure with variable micro-wire density. The first gap micro-wires 26 in the first electrode gap 60 and the second micro-wires 54 of the second micro-wire electrodes 52 are electrically isolated from the first gap micro-wires 26 in the first electrode gap 60 and the second gap micro-wires 56 in the second electrode gaps 62 by micro-wire breaks 64.
FIG. 3C illustrates the identical elements and structures illustrated in FIG. 3B. The only difference is that the first gap micro-wires 26 in the first electrode gaps 60 are now shown with solid lines as are the second micro-wires 54 of the second micro-wire electrodes 52 and the second gap micro-wires 56 in the second electrode gap 62. Both the first gap micro-wires 26 and the second micro-wires 54 are in the second layer 50 (which is also the gap layer 80).
Referring next to FIG. 3D, the first micro-wires 24 of the first micro-wire electrodes 22 separated by first electrode gaps 60 (FIG. 1A) are incorporated into the micro-wire structure of FIG. 3C to form a micro-wire electrode structure 5. In this illustration of the micro-wire electrode structure 5, the first micro-wires 24 are shown with dashed lines corresponding to the first layer 20 (e.g. as in FIG. 2D). The first gap micro-wires 26, the second micro-wires 54 of the second micro-wire electrodes 52 separated by second electrode gaps 62, and the second gap micro-wires 56 are shown with solid lines. The first gap micro-wires 26 and the second micro-wires 54 of the second micro-wire electrodes 52 are electrically connected to form an electrode with variable micro-wire density (as shown more clearly in FIG. 3C that has improved conductivity and performance. The second gap micro-wires 56 are electrically connected to first gap micro-wires 26 in the second electrode gap 62 providing variable-density dummy micro-wires that more readily shields electromagnetic radiation.
FIG. 3E is a perspective of a combination of the layers shown in FIG. 3D. In the embodiment of FIG. 3E, the second layer 50 (also the gap layer 80) is between the first layer 20 and the surface 12 of substrate 10 and display 110. If the display 110 creates electromagnetic interference, according to an embodiment of the present invention, the first gap micro-wires 26 (FIG. 3D) in the second micro-wire electrodes 52 and the second electrode gap 62 shield the first micro-wire electrodes 22 in the first layer 20 separated by the first electrode gaps 60. The micro-wire breaks 64 prevent electrical shorts between the second micro-wire electrodes 52. Thus, signals sensed by the first micro-wire electrodes 22 have an improved signal-to-noise ratio. A separate dielectric layer 40 is provided to separate the first and second micro-wire electrodes 22, 52. If the first layer 20 and second layer 50 are otherwise electrically isolated (for example by portions of the first or second layers 20, 50 as discussed further below), the dielectric layer 40 is unnecessary.
In the embodiment illustrated in the perspective of FIG. 3F, the first layer 20 is between the second layer 50 (which is also the gap layer 80) and the surface 12 of substrate 10 and the display 110. An unpatterned conductive layer 30 is in electrical contact with the first micro-wires 24 (FIG. 3D) of the first micro-wire electrodes 22 separated by first electrode gaps 60. A separate optional dielectric layer 40 is provided to separate the first micro-wire electrodes 22 from the second micro-wire electrodes 52 and the unpatterned conductive layer 30 from the second electrodes 52 separated by second electrode gaps 62. The first and second micro-wire electrodes 22, 52 extend in directions orthogonal to those of FIG. 3E. In general, the positions of the first and second layers 20, 50 and the orientations and positions of the first and second micro-wire electrodes 22, 52 can be interchanged.
The unpatterned conductive layer 30 is an electrically conductive layer with a relatively high resistance compared to the first micro-wires 24 and the first micro-wire electrodes 22 and is unpatterned within the touch-sensitive area 32 (FIG. 1A, 2C, 2D) so that at least some electrical current can flow from one first micro-wire electrode 22 to another first micro-wire electrode 22 through the unpatterned conductive layer 30. Thus, the first micro-wire electrodes 22 are not completely electrically isolated from each other. If the display 110 creates electromagnetic interference, according to an embodiment of the present invention the unpatterned conductive layer 30 shields the second micro-wire electrodes 52 in the second layer 50. Thus, signals sensed by the second micro-wire electrodes 52 have an improved signal-to-noise ratio. In embodiments, the unpatterned conductive layer 30 is patterned in areas outside the touch-sensitive area 32, for example around the periphery of a touch screen.
In the embodiment illustrated in FIGS. 3A-3F, the first gap micro-wires 26 and the second gap micro-wires 56 are located in the second layer 50. In another embodiment, at least some of the second gap micro-wires 56 are located in a layer different from the second layer 50.
FIGS. 4A, 4B, 4C and 4D are plan views of various layers of a micro-wire electrode structure 5 in various embodiments of the present invention. Combinations of the layers are shown in FIGS. 3E and 3F.
Referring first to FIG. 4A, the elements of FIG. 3A are combined with the elements of FIG. 1C to form the micro-wire electrode structure 5 of an embodiment of the present invention. As shown in FIG. 4A, the first gap micro-wires 26 in the first electrode gaps 60 between the first micro-wire electrodes 22 (FIG. 1A) are illustrated with dashed lines and the second micro-wires 54 and the second gap micro-wires 56 in the second electrode gap 62 between the second micro-wire electrodes 52 are illustrated with solid lines.
FIG. 4B illustrates the identical elements and structures illustrated in FIG. 4A. The only differences are that the first gap micro-wires 26 are now shown with solid lines representing the second layer 50 (FIG. 3E) as are the second micro-wires 54 of the second micro-wire electrodes 52. The second gap micro-wires 56 in the first micro-wire electrodes 22 (FIG. 1A) are now shown as dashed lines representing the first layer 20 (FIG. 3E). The second gap micro-wires 56 shown as dashed lines no longer include micro-wire breaks 64 with the first micro-wires 24 (FIG. 1A) since, as shown in FIG. 4C, the dashed second gap micro-wires 56 are in a different layer from the second micro-wires 54 and the second gap micro-wires 56 in the first electrode gap 60 and therefore will maintain electrical isolation between the second micro-wire electrodes 52. The absence of the micro-wire breaks 64 improves both optical uniformity and resistance to electromagnetic radiation interference.
FIG. 4C illustrates the structure of FIG. 4B with the addition of the first microwire electrodes 22 and the first micro-wires 24. In this Figure, the first micro-wires 24 of the first micro-wire electrodes 22 and the second gap micro-wires 56 in the area of the first micro-wire electrodes 22 that are not in both the first and second electrode gaps 60, 62 are shown with dashed lines that correspond to first micro-wire electrodes 22 in the first layer 20 (FIGS. 3E and 3F) and are separately shown in FIG. 4D. FIG. 4D shows the first micro-wire electrodes 22 with the first micro-wires 24 and the second gap micro-wires 56 in the area of the first micro-wire electrodes 22 forming the first micro-wire electrodes 22 with variable micro-wire density.
As shown in FIG. 4C, the second micro-wires 54 and the first gap micro-wires 26 of the second micro-wire electrodes 52 are shown with solid lines. The first and second gap micro-wires 26, 56 in both the first and second electrode gaps 60, 62 are also shown with solid lines. Solid-line micro-wires correspond to the second layer 50 (FIGS. 3E and 3F). Both the dielectric layer 40 (FIGS. 3E and 3F) and the unpatterned conductive layer 30 (FIG. 3F) are useful with the layers illustrated in FIG. C in the structures illustrated in either FIG. 3E or FIG. 3F.
The micro-wire electrode structure 5 of FIG. 4C electrically connects the first gap micro-wires 26 that are in the area of the second micro-wire electrodes 52 to the second micro-wires 54 to form more conductive second micro-wire electrodes 52 (shown in FIG. 4B). Similarly, the second gap micro-wires 56 that are in the area of the first micro-wire electrodes 22 are electrically connected to the first micro-wires 24 (as shown in FIG. 4D). Those first gap micro-wires 26 and second gap micro-wires 56 that are in neither of the areas of the first or second micro-wire electrodes 22, 52 and are therefore in both the first and second electrode gaps 60, 62, shown as dummy-wire area 36, are electrically connected and can serve as an electromagnetic interference shield for the first or second micro-wire electrodes 22, 52. Thus, at least some of the dummy micro-wires of the first layer 20 (first gap micro-wires 26) serve as second micro-wire electrode 52 micro-wires. Likewise, at least some of the dummy micro-wires of the second layer 50 (second gap micro-wires 56) serve as second micro-wire electrode 52 micro-wires. Those first gap micro-wires 26 and second gap micro-wires 56 that are located in both the first and second electrode gaps 60, 62 are therefore dummy wires electrically isolated from both the first and second micro-wire electrodes 22, 52.
In one embodiment, the first or second gap micro-wires 26, 56 in the dummy-wire area 36 are located in the second layer 50 (as shown in FIGS. 4C, 3E, and 3F), but in another embodiment are in the first layer 20. In the case in which an unpatterned conductive layer 30 is provided to electrically connect the first micro-wires 24, the first or second gap micro-wires 26, 56 in the dummy-wire area 36 are located in the second layer 50 to avoid electrically shorting the unpatterned conductive layer 30.
By locating the second gap micro-wires 56 in the area of the first micro-wire electrodes 22 in a different layer from the other second gap micro-wires 56 (those in the dummy-wire area 36), the conductivity of the first micro-wire electrodes 22 is improved. However, those second gap micro-wires 56 in the area of the first micro-wire electrodes 22 do not then serve as electromagnetic interference shields as do the second gap micro-wires in the dummy-wire area 36. Thus, the embodiment of FIG. 4C compared to the embodiment of FIG. 3D represents a different tradeoff between electrode conductivity and electromagnetic interference shielding.
In an embodiment of the present invention, the first micro-wire electrodes 22 are the drive electrodes of a capacitive touch screen and the second micro-wire electrodes 52 are the sense electrodes of the capacitive touch screen. Alternatively, the first micro-wire electrodes 22 are the sense electrodes of a capacitive touch screen and the second micro-wire electrodes 52 are the drive electrodes of the capacitive touch screen. The present invention includes a capacitive touch screen having the first and second micro-wire electrodes 22, 52 and first or second gap micro-wires 26, 56, as described above.
Referring to FIGS. 5 and 7, a method of making a micro-wire electrode structure 5 of the present invention includes providing the substrate 10 having the surface 12 in step 200. A first layer 20 is provided in relation to the surface 12 in step 205 and a plurality of first micro-wire electrodes 22 spatially separated by first electrode gaps 60 is located in the first layer 20 in step 210. Each first micro-wire electrode 22 includes a plurality of electrically connected first micro-wires 24. A second layer 50 is provided in relation to the surface 12 in step 215 and a plurality of electrically isolated second micro-wire electrodes 52 is located in the second layer 50 in step 220. The second layer 50 is at least partially different from the first layer 20 and each second micro-wire electrode 52 includes a plurality of electrically connected second micro-wires 54. A gap layer 80 different from the first layer 20 is provided in step 225 and a plurality of first gap micro-wires 26 is located in each first electrode gap in step 230. At least some of the first gap micro-wires 26 are located in the gap layer 80. The first gap micro-wires 26 are electrically isolated from the first micro-wires 24. As shown in FIG. 5, in an embodiment the second layer 50 and the gap layer 80 are the same layer and the step 215 of providing the second layer 50 is the same as the step 225 of providing the gap layer 80. Moreover, at least some of the first gap micro-wires 26 and the second micro-wires 54 are located in the same second layer 50 (and gap layer 80). In another embodiment, the step 220 of locating the second micro-wires 54 is the same as step 230 of locating the first gap micro-wires 26.
In additional embodiments of the present invention, a dielectric layer 40 is provided between the first and second layer 20, 50. In another embodiment, a protective overcoat layer 70 is provided over the second layer 50 to protect the micro-wire electrode structure 5 of the present invention and provide a touch surface 11.
Referring to FIGS. 6 and 8, another method of making a micro-wire electrode structure 5 of the present invention locates the first and second layers 20, 50 in an opposite order with respect to the surface 12. Such an embodiment includes providing the substrate 10 having the surface 12 in step 200. A second layer 50 is provided in relation to the surface 12 in step 215 and a plurality of second micro-wire electrodes 52 is located in the second layer 50 in step 250. Each second micro-wire electrode 52 includes a plurality of electrically connected second micro-wires 54 and first gap micro-wires 26. A first layer 20 is provided in relation to the surface 12 in step 205 and a plurality of electrically isolated first micro-wire electrodes 22 spatially separated by first electrode gaps 60 is located in the first layer 20 in step 210. The first layer 20 is at least partially different from the second layer 50 and each first micro-wire electrode 22 includes a plurality of electrically connected first micro-wires 24. The second layer 50 also serves as the gap layer 80 different from the first layer 20 and includes the first gap micro-wires 26. The first gap micro-wires 26 are electrically isolated from the first micro-wires 24. An optional protective overcoat layer 70 is provided over the second layer 50 to protect the micro-wire electrode structure 5 and provide a touch surface 11.
Referring to FIG. 5 again and to FIG. 9, another method of making a micro-wire electrode structure 5 of the present invention includes providing the substrate 10 having the surface 12 in step 200. A first layer 20 is provided in relation to the surface 12 in step 205 and a plurality of first micro-wire electrodes 22 spatially separated by first electrode gaps 60 is located in the first layer 20 in step 210. Each first micro-wire electrode 22 includes a plurality of electrically connected first micro-wires 24. An unpatterned conductive layer 30 is optionally provided in electrical contact with the first micro-wire electrodes 22 in step 260. In one embodiment, the first layer 20 is located between the unpatterned conductive layer 30 and the surface 12 (as shown in FIG. 5). In another embodiment, the unpatterned conductive layer 30 is located between the first layer 20 and the surface 12 (not shown). In one embodiment, the unpatterned conductive layer 30 and first layer 20 are located between the second layer 50 and the surface 12 (as shown in FIG. 5). Alternatively, the second layer 50 is located between the surface 12 and both the unpatterned conductive layer 30 and the first layer 20 (not shown, but FIG. 6 illustrates the second layer 50 between the first layer 20 and the surface 12). In an embodiment, the unpatterned conductive layer 30 is used in the structure of FIG. 6, for example by locating the unpatterned conductive layer 30 between the first layer 20 and the protective overcoat layer 70.
In yet another embodiment, an optional dielectric layer 40 is optionally located in contact with the unpatterned conductive layer 30 in step 270. In other embodiments, a portion of the first or second layers 20, 50 serves to electrically isolate micro-wires in the first layer 20 from micro-wires in the second layer 50 (e.g. as shown in FIG. 6). A second layer 50 is provided in relation to the surface 12 in step 215 and a plurality of second micro-wire electrodes 52 and first gap micro-wires 26 are located in the second layer 50 in a common step 250.
Referring to FIG. 4C, FIG. 5, and to FIG. 10, in an alternative embodiment a method of making a micro-wire electrode structure 5 of the present invention includes providing the substrate 10 having the surface 12 in step 200. A first layer 20 is provided in relation to the surface 12 in step 205 and a plurality of first micro-wire electrodes 22 spatially separated by first electrode gaps 60 is located in the first layer 20 in step 280. Each first micro-wire electrode 22 includes a plurality of electrically connected first micro-wires 24 and at least some second gap micro-wires 56 located at the same time in the same step 280. A second layer 50 is provided in relation to the surface 12 in step 215 and a plurality of second micro-wire electrodes 52 spatially separated by second electrode gaps 62 is located in the second layer 50 in step 250. Each second micro-wire electrode 52 includes a plurality of electrically connected second micro-wires 54 and at least some first gap micro-wires 26 located at the same time in the same step 250.
In useful embodiments of the present invention, in step 250 the second micro-wire electrodes 52 are formed in a single step in the second layer 50 so that the second micro-wires 54 and first gap micro-wires 26 are likewise formed in a single step and are formed from a common material. Likewise, in step 280 the first micro-wire electrodes 22 are formed in a single step in the first layer 20 so that the first micro-wires 24 and second gap micro-wires 56 are formed in a single step and are formed from a common material.
In an embodiment, the unpatterned conductive layer 30 in electrical contact with the first micro-wires 24 of the first micro-wire electrodes 22 is provided before the second layer 50 is located. In other embodiments of the present invention, the first layer 20 is located with respect to the surface 12 before the second layer 50 is provided. For example, the first layer 20 is formed on the surface 12 and the second layer 50 is subsequently formed on the first layer 20, or on layers such as the unpatterned conductive layer 30 or dielectric layer 40 formed on the first layer 20, so that the first layer 20 is between the surface 12 and the second layer 50. Alternatively, the second layer 50 is located with respect to the surface 12 before the first layer 20 is provided. For example, the second layer 50 is formed on the surface 12 and the first layer 20 is subsequently formed on the second layer 50, or on layers such as the unpatterned conductive layer 30 or dielectric layer 40 formed on the second layer 50, so that the second layer 50 is between the surface 12 and the first layer 20.
In a further embodiment of a method of the present invention, a display substrate or a display cover having the surface 12 is provided so that the display cover or display substrate is the substrate 10. Alternatively, the substrate 10 is affixed to the display 110. In an embodiment, the display 110 is a source of electromagnetic radiation.
In yet another embodiment, the micro-wire electrode structure 5 is peeled from the substrate 10 and applied to another substrate, such as the display substrate or display cover. The micro-wire electrode structure 5 is applied with either side adjacent to the other substrate, effectively enabling a reversal of layer order with respect to the other substrate. In such a structure, the end result is that the first and second micro-wires 24, 25 are effectively located at the bottom of their respective first and second layers 20, 50.
Referring to FIG. 14, the structure of FIG. 6 is constructed with the unpatterned conductive layer 30 in place of the overcoat layer 70 (FIG. 6) in electrical contact with the first micro-wire electrodes 22 and first micro-wires 24 in first layer 20 separated by first electrode gaps 60. The micro-wire electrode structure 5 is peeled from the surface 12 of the substrate 10 (FIG. 6) and applied to another substrate (shown as the display 110) with the unpatterned conductive layer 30 in contact with the other substrate and the second layer 50 (also the gap layer 80) with second micro-wire electrodes 52 having second micro-wires 54 and first gap micro-wires 26 on the opposite side of the first layer 20.
In a useful embodiment that provides optical uniformity, the first micro-wire electrodes 22 are provided in a first micro-pattern that is similar to a second micro-pattern in which the second micro-wires 54 are provided but offset from the first micro-pattern in a direction parallel to the surface by a spatial phase difference of 180 degrees.
In various embodiments of the present invention, various layers are formed from a curable material, such as a polymer or resin that is coated in a liquid form and then cured to form a solid, for example by exposure to ultra-violet radiation or heat. Curable materials can include cross-linking materials.
According to various embodiments of the present invention, micro-wires are provided in association with layers in various ways. In one embodiment, micro-wires are formed on a layer surface, for example by printing on surface 12 and then coated with a curable layer that is then cured. In such an embodiment, the micro-wires are located at the bottom of the layer. In another embodiment, conductive ink is printed, for example by inkjet, gravure, or flexographic printing, on top of a layer surface and then cured. Alternatively, micro-channels are imprinted in an uncured layer, the layer is cured, and then conductive ink supplied in the micro-channels and cured to form micro-wires. In yet another method, layers are laminated together. Laminated layers can include micro-wires in a pre-formed pattern. Coating methods such as spin coating, curtain coating, slot coating, extrusion coating, and hopper coating are known in the art as are printing methods such as ink jet, gravure, and flexographic printing. Lamination methods are well known. Conductive inks are also known as are method for imprinting and filling micro-channels.
First micro-wires 24 can extend partially or all of the way through the first layer 20. The unpatterned conductive layer 30 and the first layer 20 can be the same common layer and first micro-wires 24 formed in, on, or under the common layer. The unpatterned conductive layer 30 and the first layer 20 can be coated together, for example with slot or extrusion coating. The first or second layers 20, 50 can be imprinted with a stamp having protrusions as deep as or deeper than the depth of the respective layers. The unpatterned conductive layer 30 can be coated on the first layer 20 and in contact with the first micro-wires 24. In an embodiment, the first or second layers 20, 50 are cured to form micro-channels that are filled with conductive ink and to form first or second micro-wires 24, 54. The dielectric layer 40, second layer 50, or overcoat layer 70 are also formed using known coating methods.
In embodiments of the present invention, the electrical resistance of the unpatterned conductive layer 30 is greater than the resistance of each of the first or second micro-wire electrodes 22, 52. In tests, the resistance of the unpatterned conductive layer 30 was measured as the sheet resistance of the unpatterned conductive layer 30 independently of the first or second micro-wires 24, 54. The resistance of the first or second micro-wire electrodes 22, 52 is the resistance measured along the length of the first or second micro-wire electrodes 22, 52.
In an embodiment, the unpatterned conductive layer 30 has a sheet resistance greater than 1 kΩ per square, greater than 10 kΩ/per square, greater than 100 kΩ per square, greater than 1 MΩ per square, greater than 10 MΩ per square, greater than 100 MΩ per square, greater than 1 GΩ per square, greater than 10 GΩ per square, or greater than 100 GΩ per square. This lower limit in resistivity of the unpatterned conductive layer 30 is dependent in part on the frequency at which the first or second micro-wire electrodes 22, 52 are driven and on the touch-screen controller 140 current and voltage characteristics and on the conductivity of the first or second micro-wire electrodes 22, 52.
In another embodiment, the resistance of the unpatterned conductive layer 30 between any two first micro-wire electrodes 22 is at least five times greater, at least ten times greater, at least twenty times greater, at least fifty times greater, at least 100 times greater, at least 500 times greater, at least 1,000 times greater, at least 10,000, at least 100,000, or at least 1,000,000 times greater than the resistance of either of the any two first micro-wire electrodes 22. In one embodiment, the resistance of the unpatterned conductive layer 30 between the first micro-wire electrodes 22 separated by the first electrode gap 60 is at least ten times greater than the resistance of any of the first micro-wire electrodes 22.
In a further embodiment of the present invention, the touch-screen controller 140, for example an integrated circuit, for driving the first micro-wire electrodes 22 provides voltage and current to the first micro-wire electrodes 22 in a desired driver waveform having a period and frequency. The frequency of the driver waveform limits the rate at which the capacitance between the first and second micro-wire electrodes 22, 52 can be measured. Because the unpatterned conductive layer 30 is electrically connected to the first micro-wire electrode 22 and has a limited conductivity, the rate at which the first micro-wire electrode 22 and the unpatterned conductive layer 30 can be charged is likewise limited. A micro-wire electrode, such as the first micro-wire electrode 22, has open areas between the micro-wires in the micro-wire electrode that, according to the present invention, are filled with conductive material in the unpatterned conductive layer 30. Thus, the conductivity of the unpatterned conductive layer 30 will define, in combination with the open area defined by the geometry of the first micro-wires 24 in the first micro-wire electrode 22, the rate at which the first micro-wire electrode 22 and the unpatterned conductive layer 30 can be charged or discharged. Therefore, the conductivity of the unpatterned conductive layer 30 and the open area define the time constant for charging or discharging the first micro-wire electrode 22 and the center of the open area in response to a voltage change as provided by the driver waveform. Therefore, according to the further embodiment of the present invention, the sheet resistance of the unpatterned conductive layer 30 is sufficiently low that the time constant for charging the center of the open area between first micro-wires 24 in the first micro-wire electrode 22 is less than the period of a driver waveform. In another embodiment, the time constant is substantially less than the period. By substantially less is meant at least 5% less, at least 10% less, at least 20% less, or at least 50% less.
In operation, a touch-screen controller (for example touch-screen controller 140 of FIG. 11) energizes one of the first micro-wire electrodes 22 with a signal and senses one of the second micro-wire electrode 52 to detect the capacitance or changes in capacitance of the area overlapped by the one first micro-wire electrode 22 and one second micro-wire electrode 52. For such an application, the first micro-wire electrodes 22 extending in a first direction parallel to the surface 12 are located orthogonally to the second micro-wire electrodes 52 extending in a second direction D2 parallel to the surface and orthogonal to the first direction D1.
Since the unpatterned conductive layer 30 electrically connects the first micro-wire electrodes 22, some current leaks from the driven first micro-wire electrode 22 to other first micro-wire electrodes 22. However, because the resistance of the unpatterned conductive layer 30 is high relative to the resistance of the first micro-wire electrodes 22, capacitance is still detected in the overlapped electrode area. Moreover, the presence of the unpatterned conductive layer 30 inhibits electromagnetic interference from affecting the capacitance measure by the second micro-wire electrode 52, especially if the electromagnetic interference originates from a side of the unpatterned conductive layer 30 opposite the second micro-wire electrodes 52. Furthermore, the unpatterned conductive layer 30 assists in extending the electrical field produced by driving the first micro-wires 24 in the one first micro-wire electrode 22 into the spaces between the first micro-wires 24, thereby providing a more uniform field between the first micro-wire electrode 22 and the second micro-wire electrode 52. A more uniform field enables a more consistent and sensitive detection of capacitance changes due to the presence of perturbing elements such as a finger or a stylus at varying spatial locations. Furthermore, the presence of the unpatterned conductive layer 30 reduces the sensitivity of the touch-screen device to differences in alignment between the micro-wires of the first micro-wire electrodes 22 and the second micro-wire electrodes 52.
In comparison to other prior-art solutions using a separate ground plane beneath driver or sensor electrodes to reduce the effect of electro-magnetic radiation, for example from a display located beneath the touch screen, the present invention provides a thinner touch-screen and display structure with fewer layers.
A variety of techniques are usable to construct a touch screen device of the present invention. In various embodiments, the patterned first micro-wire electrodes 22 are formed in a layer, such as first layer 20, unpatterned conductive layer 30, or dielectric layer 40, printed or transferred onto a layer, such as the substrate 10, unpatterned conductive layer 30, or dielectric layer 40, or laminated on the substrate 10 or other layer on the substrate 10. In other embodiments, the unpatterned conductive layer 30 is laminated, coated, formed by evaporation, sputtering, or chemical vapor deposition, or formed by atomic layer deposition on the first micro-wire electrodes 22 or first layer 20 or on the second layer 50. The dielectric layer 40 is laminated, coated, formed by evaporation, sputtering, or chemical vapor deposition, or formed by atomic layer deposition on the unpatterned conductive layer 30. The patterned second micro-wire electrodes 52 are formed in a layer, such as second layer 50 or dielectric layer 40, printed or transferred onto a layer, such as the substrate 10 or dielectric layer 40, or laminated on the substrate 10 or other layer on the substrate 10.
In an embodiment, unpatterned conductive layer 30 or dielectric layer 40 is deposited by sputtering or deposition and patterned outside the touch-sensitive area 32 either with masks or by photolithographic processes. In an embodiment, conductive material is only deposited in the touch-sensitive area 32. Alternatively, conductive material is deposited over the entire substrate 10 and removed as needed, for example in peripheral regions of the touch screen outside the touch-sensitive area 32. In another embodiment, atomic layer deposition methods are used to form a transparent conductive layer, for example a patterned aluminum zinc oxide layer using methods known in the art. Patterning outside the touch-sensitive area 32 is accomplished, for example, by masking the deposition, using patterned deposition inhibitors, or by photolithographic processes.
In an embodiment, the substrate 10 and the surface 12 are provided in step 200, together with imprinting stamps. The first layer 20 is provided on the substrate 10 and surface 12 in step 205, for example by coating. The patterned first micro-wire electrodes 22 are formed by imprinting the first layer 20 with an imprinting stamp, curing the first layer 20 to form the first micro-channels that are filled with conductive ink. The conductive ink is cured to form first micro-wires 24 and optional second gap micro-wires 56 located in the first micro-channels in step 210 or step 280. The unpatterned conductive layer 30 is coated over the first micro-wires 24 in step 260 and the optional dielectric layer 40 is optionally coated over the unpatterned conductive layer 30 in step 270. The patterned second micro-wire electrodes 52 are formed by coating and imprinting the second layer 50 with an imprinting stamp, curing the second layer 50 to form second micro-channels that are filled with conductive ink. The conductive ink is cured in step 250 to form the second micro-wires 54 and form the first gap micro-wires 26.
In other embodiments, imprinting methods are used to imprint first micro-channels in the dielectric layer 40 or in the unpatterned conductive layer 30. Similarly, in other embodiments imprinting methods are used to imprint second micro-channels in the dielectric layer 40.
Printing methods are usable in other embodiments of the present invention. A conductive ink is printable, for example with a flexographic plate, on a substrate 10 or other layer and cured to form micro-wires. Alternatively, a pattern of micro-wires is transferrable to the substrate 10 or other layer from another substrate.
In an alternative embodiment, micro-wires are formed by coating a flexographic substrate having a raised pattern corresponding to a desired micro-wire pattern with a conductive ink. The flexographic substrate is brought into contact with a layer surface to print the conductive ink onto the layer surface. In an optional step, the conductive ink is dried. Flexographic substrates are known in the flexographic printing arts.
Transferred or printed micro-wires can be coated with curable material to form the first layer 20 or second layer 50. The first layer 20 or second layer 50 can also be the dielectric layer 40. In an embodiment, the unpatterned conductive layer 30 is the first layer 20.
In yet another embodiment, layer structures are laminated to another layer. For example, the first layer 20 is made as a separate construction (for example as a layer of PET) including first micro-wires 24 and then laminated with an adhesive to substrate 10. Second layer 50 is made and similarly laminated. The unpatterned conductive layer 30 or dielectric layer 40 can be laminated onto their respective layers, together or separately. In another embodiment, a layer structure is formed on a temporary substrate with a temporary adhesive on a first side, the layer structure is permanently adhered to the substrate 10 or layer formed on the substrate 10 on a second side, and then the temporary substrate is removed from the first side, for example by peeling.
In various embodiments, the unpatterned conductive layer 30 is laminated, coated, or deposited on the first micro-wire electrodes 22. In an embodiment, atomic layer deposition is used to form the unpatterned conductive layer 30. In other embodiments, the dielectric layer 40 is laminated, coated, or deposited on the first micro-wire electrodes 22.
Dielectric layer 40 can be any of many known dielectric materials included polymers or oxides and are deposited or formed in any of a variety of known ways, including pattern-wise inkjet deposition, sputtering, or coating through a mask or blanket coated and patterned using known photo-lithographic methods. Such known photo-lithographic technology can include a photo-sensitive material that is optically patterned through a mask to cure the photo-sensitive material and removal of either the cured or the uncured material.
In an embodiment, unpatterned conductive layer 30 is transparent and includes one or more of a variety of transparent conductive materials, for example organic conductive polymers such as Poly(3,4-ethylenedioxythiophene) (PEDOT), Poly(3,4-ethylenedioxythiophene) PEDOT: poly(styrene sulfonate) PSS, Poly(4,4-dioctylcyclopentadithiophene), and Polypyrrole (PPy), long-chain aliphatic amines (optionally ethoxylated) and amides, quaternary ammonium salts (such as, behentrimonium chloride or cocamidopropyl betaine), esters of phosphoric acid, polyethylene glycol esters, or polyols, polyaniline nanofibers, carbon nanotubes, graphene, metals such as silver nanowires, and inorganic conductive oxides such as ITO, SnO₂, In₂O₃, ZnO, Aluminum-doped zinc oxide (AZO), CdO, Ga₂O₃, V₂O₅. Deposition methods for conductive materials can include solvent or aqueous coating, printing by for example inkjet, gravure, offset litho, flexographic, or electro-photographic, lamination, evaporation, chemical vapor deposition (CVD), sputtering, atomic-layer deposition (ALD) or spatial-atomic-layer deposition (SALD).
In another embodiment, unpatterned conductive layer 30 is an ionic conductor, a solid ionic conductor, an electrolyte, a solid electrolyte, or a conductive gel, as are known in the art.
In an embodiment, the unpatterned conductive layer 30 has a thickness less than or equal to 50 nm, 100 nm, 200 nm, 500 nm, or 1 micron. In other embodiments, the unpatterned conductive layer 30 has a thickness less than or equal to 10 microns, 100 microns, 200 microns, 500 microns, or 1 mm.
According to various embodiments of the present invention, the substrate 10 is any material on which a layer is formed. The substrate 10 is a rigid or a flexible substrate made of, for example, a glass, metal, plastic, or polymer material, is transparent, and can have opposing substantially parallel and extensive surfaces. The substrates 10 can include a dielectric material useful for capacitive touch screens and can have a wide variety of thicknesses, for example 10 microns, 50 microns, 100 microns, 1 mm, or more. In various embodiments of the present invention, substrates 10 are provided as a separate structure or are coated on another underlying substrate, for example by coating a polymer substrate layer on an underlying glass substrate.
In various embodiments the substrate 10 is an element of other devices, for example the cover or substrate of a display or a substrate, cover, or dielectric layer of a touch screen. In an embodiment, the substrate 10 of the present invention is large enough for a user to directly interact therewith, for example using an implement such as a stylus or using a finger or hand. Methods are known in the art for providing suitable surfaces on which to coat or otherwise form layers. In a useful embodiment, the substrate 10 is substantially transparent, for example having a transparency of greater than 90%, 80% 70% or 50% in the visible range of electromagnetic radiation.
Electrically conductive micro-wires and methods of the present invention are useful for making electrical conductors and buses for transparent micro-wire electrodes and electrical conductors in general, for example as used in electrical buses. A variety of micro-wire patterns are used and the present invention is not limited to any one pattern. Micro-wires can be spaced apart, form separate electrical conductors, or intersect to form a mesh electrical conductor on, in, or above the substrate 10. Micro-channels can be identical or have different sizes, aspect ratios, or shapes. Similarly, micro-wires can be identical or have different sizes, aspect ratios, or shapes. Micro-wires can be straight or curved.
A micro-channel is a groove, trench, or channel formed on or in a layer extending from the surface of the layer and having a cross-sectional width for example less than 20 microns, 10 microns, 5 microns, 4 microns, 3 microns, 2 microns, 1 micron, or 0.5 microns, or less. In an embodiment, the cross-sectional depth of a micro-channel is comparable to its width. Micro-channels can have a rectangular cross section. Other cross-sectional shapes, for example trapezoids, are known and are included in the present invention. The width or depth of a layer is measured in cross section. Micro-channels are not distinguished in the Figures from the micro-wires.
Imprinted layers useful in the present invention can include a cured polymer material with cross-linking agents that are sensitive to heat or radiation, for example infra-red, visible light, or ultra-violet radiation. The polymer material is a curable material applied in a liquid form that hardens when the cross-linking agents are activated. When a molding device, such as an imprinting stamp having an inverse micro-channel structure is applied to liquid curable material and the cross-linking agents in the curable material are activated, the liquid curable material in the curable layer is hardened into a cured layer with imprinted micro-channels. The liquid curable materials can include a surfactant to assist in controlling coating. Materials, tools, and methods are known for embossing coated liquid curable materials to form cured layers.
A cured layer is a layer of curable material that has been cured. For example, a cured layer is formed of a curable material coated or otherwise deposited on a layer surface to form a curable layer and then cured to form the cured layer. The coated curable material is considered herein to be a curable layer before it is cured and cured layer after it is cured. Similarly, a cured electrical conductor is an electrical conductor formed by locating a curable material in micro-channel and curing the curable material to form a micro-wire in a micro-channel. As used herein, curing refers to changing the properties of a material by processing the material in some fashion, for example by heating, drying, irradiating the material, or exposing the material to a chemical, energetic particles, gases, or liquids.
The curable layer is deposited as a single layer in a single step using coating methods known in the art, such as curtain coating. In an alternative embodiment, the curable layer is deposited as multiple sub-layers using multi-layer deposition methods known in the art, such as multi-layer slot coating, repeated curtain coatings, or multi-layer extrusion coating. In yet another embodiment, the curable layer includes multiple sub-layers formed in different, separate steps, for example with a multi-layer extrusion, curtain coating, or slot coating machine as is known in the coating arts.
Curable inks useful in the present invention are known and can include conductive inks having electrically conductive nano-particles, such as silver nano-particles. In an embodiment, the electrically conductive nano-particles are metallic or have an electrically conductive shell. The electrically conductive nano-particles can be silver, can be a silver alloy, or can include silver. In various embodiments, cured inks can include metal particles, for example nano-particles. The metal particles are sintered to form a metallic electrical conductor. The metal nano-particles are silver or a silver alloy or other metals, such as tin, tantalum, titanium, gold, copper, or aluminum, or alloys thereof. Cured inks can include light-absorbing materials such as carbon black, a dye, or a pigment.
Curable inks provided in a liquid form are deposited or located in first or second micro-channels and cured, for example by heating or exposure to radiation such as infra-red radiation, visible light, or ultra-violet radiation. The curable ink hardens to form the cured ink that makes up first or second micro-wires 24, 54. For example, a curable conductive ink with conductive nano-particles are located within first or second micro-channels and cured by heating or sintering to agglomerate or weld the nano-particles together, thereby forming an electrically conductive first or second micro-wire 24, 54. Materials, tools, and methods are known for coating liquid curable inks to form micro-wires.
In an embodiment, a curable ink can include conductive nano-particles in a liquid carrier (for example an aqueous solution including surfactants that reduce flocculation of metal particles, humectants, thickeners, adhesives or other active chemicals). The liquid carrier is located in micro-channels and heated or dried to remove liquid carrier or treated with hydrochloric acid, leaving a porous assemblage of conductive particles that are agglomerated or sintered to form a porous electrical conductor in a layer. Thus, in an embodiment, curable inks are processed to change their material compositions, for example conductive particles in a liquid carrier are not electrically conductive but after processing form an assemblage that is electrically conductive.
Once deposited, the conductive inks are cured, for example by heating. The curing process drives out the liquid carrier and sinters the metal particles to form a metallic electrical conductor. Conductive inks are known in the art and are commercially available. In any of these cases, conductive inks or other conducting materials are conductive after they are cured and any needed processing completed. Deposited materials are not necessarily electrically conductive before patterning or before curing. As used herein, a conductive ink is a material that is electrically conductive after any final processing is completed and the conductive ink is not necessarily conductive at any other point in the micro-wire formation process.
In various embodiments of the present invention, micro-channels or micro-wires have a width less than or equal to 10 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 micron. In an example and non-limiting embodiment of the present invention, each micro-wire is from 10 to 15 microns wide, from 5 to 10 microns wide, or from 5 microns to one micron wide. In some embodiments, micro-wires can fill micro-channels; in other embodiments micro-wires do not fill micro-channels. In an embodiment, the micro-wires are solid; in another embodiment, the micro-wires are porous.
Micro-wires can be metal, for example silver, gold, aluminum, nickel, tungsten, titanium, tin, or copper or various metal alloys including, for example silver, gold, aluminum, nickel, tungsten, titanium, tin, or copper. Micro-wires can include a thin metal layer composed of highly conductive metals such as gold, silver, copper, or aluminum. Other conductive metals or materials are usable. Alternatively, micro-wires can include cured or sintered metal particles such as nickel, tungsten, silver, gold, titanium, or tin or alloys such as nickel, tungsten, silver, gold, titanium, or tin. Conductive inks are used to form micro-wires with pattern-wise deposition or pattern-wise formation followed by curing steps. Other materials or methods for forming micro-wires, such as curable ink powders including metallic nano-particles, are employed and are included in the present invention.
Electrically conductive micro-wires of the present invention are operable by electrically connecting micro-wires through connection pads and electrical connectors to electrical circuits that provide electrical current to micro-wires and can control the electrical behavior of micro-wires. Electrically conductive micro-wires of the present invention are useful, for example in touch screens such as projected-capacitive touch screens that use transparent micro-wire electrodes and in displays. Electrically conductive micro-wires can be located in areas other than display areas, for example in the perimeter of the display area of a touch screen, where the display area is the area through which a user views a display.

Inventive Example

The second micro-wire electrodes 52 including the second micro-wires 54 but excluding the first gap micro-wires 26 were prepared using a standard lithographic process. Microposit 1813 photoresist was spin-coated onto a 1000 Å thermally deposited aluminum layer coated on a 2.5 inch by 2.5 inch square 4 mil PET support. The photoresist was exposed to UV light through a chrome-on-quartz mask, developed, rinsed and dried. The film was then etched in PAN etch leaving a positive image having 10 μm wide aluminum micro-wires forming connected open right-angle-diamond electrodes, 1600 μm on diagonal. The periodic width of the second micro-wire electrodes 52 was 6.42 mm separated by 400 micron micro-wire breaks 64 in the second micro-wires 54 at intersections between the second micro-wire electrodes 52. The second micro-wire electrodes 52 were terminated with conductive rectangular pads to enable simple resistance measurements end-to-end. The pads at one end of the second micro-wire electrodes 52 also had conductive bus lines leading to additional pads at the edge of the support (the dielectric layer 40) to enable conventional 1 mm pitch edge connection with electrical test fixtures. The photoresist was removed with acetone and methanol baths and dried with nitrogen. The second micro-wire electrode 52 resistance was measured to be on the order of 450Ω from end-to-end and essentially infinite between nearest neighbor electrodes.
The first micro-wire electrodes 22 including the first micro-wires 24 but excluding the second gap micro-wires 56 were prepared as were the second micro-wire electrodes 52, on a separate 4 mil PET support (substrate 10), and with the final addition of a transparent unpatterned conductive layer 30 formed on the lithographically patterned first micro-wires 24 by spin coating a solution of PEDOT/PSS at 3000 rpm and drying on a hotplate for 2 minutes at 110° C. Sheet resistance of the dried PEDOT/PSS coating on a section of bare PET support using a four-point probe was 8 MΩ/square. First electrode resistance was measured to be on the order of 450Ω from end-to-end with approximately 160 kΩ between nearest neighbor electrodes. Thus the ratio of shorting resistance to first electrode resistance in this inventive example was 356 to 1.
A functional touch-screen was fabricated from the prepared second and first micro-wire electrodes 52, 22 by first laminating a cover sheet of 4 mil PET (overcoat layer 70) on the exposed side of the second micro-wire electrodes 52 on dielectric layer 40 using optically clear adhesive, OCA (Adhesives Research, ARClear 8154 Optically Clear Unsupported Transfer Adhesive) to form a coversheet (overcoat layer 70) of the touch-screen example. The second micro-wire electrodes 52 were oriented 90 degrees with respect to the first micro-wire electrodes 22 and offset such that the intersections of the diamonds were directly above the center of the diamonds of the first micro-wire electrodes 22. The uncoated side of the dielectric layer 40 was laminated to the exposed side of the unpatterned conductive layer 30 using the same optically clear adhesive. The dielectric thus includes both the OCA and the 4 mil PET dielectric layer 40.

Comparative Example

For the purpose of comparison, a control touch-screen representing an example of the prior art was prepared exactly as described above except the coating of PEDOT/PSS forming the unpatterned conductive layer 30 was eliminated in the comparative example.

Results:

The measurement apparatus included two translation stages which were used to move a mechanical, artificial finger incrementally across the sample. The weight of the finger was used to provide a constant touch force and the tip of the artificial finger included a compliant, conductor loaded, polymer foam mounted on the end of a conductive rod. All but one first micro-wire electrode 22 were held at ground while a voltage waveform including a controlled burst of sine waves (either 100 kHz or 1 MHz) was applied to one of the first micro-wire electrodes 22. All of the second micro-wire electrodes 52 were held at ground and one was connected to a charge sensitive pre-amplifier (operational amplifier with capacitor feedback) which held the second micro-wire electrodes 52 at ground and output a voltage proportional to the input charge. The output voltage from the sensing amplifier was sampled periodically at 20 MHz. Digital processing was used to synchronously (with respect to the driven waveform) rectify the sampled signal and compute an average (in phase) voltage. By spatially stepping the artificial finger across the sample in a spatial matrix of locations, the sensed voltages are mapped as a function of the artificial finger location. By inference, the response of a single repetitive unit at a single location is the same as the response at any other location (except for boundaries). By measuring a known conventional capacitor with the same instrument, the voltage reading is converted to effective capacitance readings.
The mutual no-touch capacitance for the inventive example was 1.8 times higher than the comparative example at either 100 kHz or 1 MHz. This increase illustrates the effective field-spreading characteristic of the unpatterned conductive layer 30 in the inventive example at practical measurement frequencies and is usable to reduce the relative power consumption of a touch-sensor controller resulting in improved system efficiency.
To test touch sensitivity, the examples were scanned with a 10.4 mm diameter artificial finger in a matrix pattern centered at an intersection of the active second and first micro-wire electrodes 52, 22. In each case, far from the intersection, the capacitance was equivalent to the no-touch condition, as expected. Centered on the intersection the capacitance was less than the no-touch condition and the relative difference between the near node touch and no-touch reading was taken as a measure of the touch sensitivity.
Touch-Sensitivity=−(C _touch −C _no _— _touch)/C _no _— _touch
At 1 MHz the relative touch sensitivity was 42% for the inventive example and 50% for the comparative example. Thus, the touch signal in the inventive example was strong and differences between the inventive and comparative example small, demonstrating that the unpatterned conductive layer 30 has minimal effect on the touch sensitivity while increasing the capacitance. The observed difference in touch sensitivity can be due in part or entirely to imperfections of the alignment of driver and sensor electrodes (first and second micro-wire electrodes 22, 52) in each example.
To test the shielding properties, connections to the second and first micro-wire electrodes 52, 22 were exchanged thus reversing the roles of the first and second micro-wire electrodes 22, 52 and the artificial finger was scanned over the back-side of the examples. By symmetry this makes no difference for the comparative example but shows a reduction in touch sensitivity due to the shielding effects of the field-spreading unpatterned conductive layer 30 in the inventive example. Indeed, the results showed a factor of 3 reductions in touch sensitivity at 1 MHz and complete elimination of touch signal at 100 kHz for the inventive example. This reduction in frequency response is an illustration of the time constant for charging or discharging the open areas of the unpatterned conductive layer 30 in the first micro-wire electrode 22. Touch sensitivity of the comparative example was unaffected, as expected. Thus the field spreading unpatterned conductive layer 30 in the inventive example exhibited highly effective shielding at practical frequencies with no deleterious effects due to electrical shorting between first micro-wire electrodes 22. Capacitance signal increased and little change in touch sensitivity was observed when driven and sensed in the intended configuration achieving a considerable improvement in overall system efficiency relative to the prior art example was demonstrated.
Methods and devices for forming and providing substrates and coating substrates are known in the photo-lithographic arts. Likewise, tools for laying out electrodes, conductive traces, and connectors are known in the electronics industry as are methods for manufacturing such electronic system elements. Hardware controllers for controlling touch screens and displays and software for managing display and touch screen systems are well known. These tools and methods are usefully employed to design, implement, construct, and operate the present invention. Methods, tools, and devices for operating capacitive touch screens are used with the present invention.
In addition to the inventive and comparative examples described, a touch-screen structure of the present invention having a PEDOT/PSS unpatterned conductive layer 30 was constructed using the imprinting techniques described and, in a separate sample, an unpatterned conductive layer 30 of AZO on etched first micro-wires 24 was formed using atomic-layer deposition methods.
The first or second micro-wire electrodes 22, 52 can be formed in a variety of patterns. Electrodes can be rectangular and arranged in regular arrays. The first micro-wire electrodes 22 and the second micro-wire electrodes 52 can be arranged orthogonally to each other. Alternatively, electrodes can be arranged using polar coordinates, in circles, or in other curvilinear patterns. Electrodes can have uniform spacing or widths. Alternatively, electrodes can have non-uniform spacing and variable widths.
The present invention is useful in a wide variety of electronic devices. Such devices can include, for example, photovoltaic devices, OLED displays and lighting, LCD displays, plasma displays, inorganic LED displays and lighting, electrophoretic displays, electrowetting displays, dimming mirrors, smart windows, transparent radio antennae, transparent heaters and other touch-screen devices such as capacitive touch screen devices.
The invention has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

PARTS LIST

P direction
D1 direction
D2 direction
5 micro-wire electrode structure
10 substrate
11 touch surface
12 surface
20 first layer
22 first micro-wire electrode
24 first micro-wire
26 first gap micro-wires
30 unpatterned conductive layer
32 touch-sensitive area
36 dummy-wire area
40 dielectric layer
50 second layer
52 second micro-wire electrode
54 second micro-wire
56 second gap micro-wires
60 first electrode gap
62 second electrode gap
64 micro-wire breaks
70 overcoat layer
80 gap layer
100 display and touch-screen apparatus
110 display
120 touch screen
122 first transparent substrate
124 dielectric layer
126 second transparent substrate
128 touch pad area
130 first electrode
132 second electrode
134 wires
136 electrical bus connections
140 touch-screen controller
142 display controller
150 micro-wire
152 dummy micro-wires
156 micro-pattern
200 provide substrate surface step
205 provide first layer step
210 locate first micro-wires step
215 provide second layer step
220 locate second micro-wires step
225 provide gap layer step
230 locate gap micro-wires step
250 locate second micro-wires and first gap micro-wires step
260 provide unpatterned conductive layer step
270 locate dielectric layer step
280 locate first micro-wires and second gap micro-wires step

Claims

1. A micro-wire electrode structure, comprising:

a substrate having a surface;

a plurality of first micro-wire electrodes spatially separated by first electrode gaps located in a first layer in relation to the surface, each first micro-wire electrode including a plurality of electrically connected first micro-wires;

a plurality of electrically isolated second micro-wire electrodes located in a second layer in relation to the surface, the second layer at least partially different from the first layer and each second micro-wire electrode including a plurality of electrically connected second micro-wires; and

a plurality of first gap micro-wires located in each first electrode gap, at least some of the first gap micro-wires located in a gap layer different from the first layer, the first gap micro-wires electrically isolated from the first micro-wires.

2. The micro-wire electrode structure of claim 1, further including an unpatterned conductive layer in electrical contact with the first micro-wires of the first micro-wire electrodes.

3. The micro-wire electrode structure of claim 1, wherein the gap layer is the second layer and wherein at least some of the first gap micro-wires are located within the second micro-wire electrodes and are electrically connected to the second micro-wires.

4. The micro-wire electrode structure of claim 1, wherein the second micro-wire electrodes are spatially separated by second electrode gaps and further including a plurality of second gap micro-wires located in each second electrode gap, the second gap micro-wires electrically isolated from the second micro-wires.

5. The micro-wire electrode structure of claim 4, wherein at least some of the second gap micro-wires and at least some of the first gap micro-wires are located in a common layer parallel to the surface or wherein the second gap micro-wires are located in the first layer.

6. The micro-wire electrode structure of claim 5, wherein at least some of the second gap micro-wires are located within the first micro-wire electrodes and are electrically connected to the first micro-wires.

7. The micro-wire electrode structure of claim 5, wherein at least some of the first gap micro-wires are within the second micro-wire electrodes and are electrically connected to the second micro-wires.

8. The micro-wire electrode structure of claim 6, wherein at least some of the first gap micro-wires are within the second electrode gap and are electrically connected to the second gap micro-wires.

9. The micro-wire electrode structure of claim 1, wherein the first layer is between the second layer and the surface.

10. The micro-wire electrode structure of claim 9, further including an unpatterned conductive layer in electrical contact with the first micro-wires of the first micro-wire electrodes.

11. The micro-wire electrode structure of claim 9, wherein the first micro-wire electrodes are the drive electrodes of a capacitive touch screen and the second micro-wire electrodes are the sense electrodes of the capacitive touch screen.

12. The micro-wire electrode structure of claim 1, wherein the second layer is between the first layer and the surface.

13. The micro-wire electrode structure of claim 12, wherein the first micro-wire electrodes are the sense electrodes of a capacitive touch screen and the second micro-wire electrodes are the drive electrodes of the capacitive touch screen.

14. The micro-wire electrode structure of claim 1, wherein the substrate is a display cover or a display or the substrate is affixed to a display and the display is the source of electromagnetic radiation.

15. The micro-wire electrode structure of claim 1, wherein the first micro-wire electrodes extend in a first direction parallel to the surface, the second micro-wire electrodes extend in a second direction parallel to the surface.

16. The micro-wire electrode structure of claim 15, wherein the first direction is orthogonal to the second direction.

17. The micro-wire electrode structure of claim 15, wherein the first micro-wires form a first pattern and the second micro-wires form a second pattern similar to the first pattern.

18. The micro-wire electrode structure of claim 17, wherein the first pattern is spatially offset from the second pattern in a direction parallel to the surface by a phase difference of 180 degrees.

19. The micro-wire electrode structure of claim 1, wherein the first micro-wire electrodes are electrically isolated.

20. A capacitive touch screen device having the first micro-wire electrodes, the second micro-wire electrodes, and the first gap micro-wires of claim 1.