Patent Application
20140055688
Touch-sensitive displays such as those found on portable and stationary electronics may be resistive touch screens. When pressure by a finger, stylus, or other appendage is applied to a resistive touch screen two flexible substrates coated with a resistive material are pressed together and the horizontal and vertical lines that are respectively located on the two substrates make contact, the location of the touch is registered.
In an embodiment, a method for manufacturing a resistive touch sensor circuit comprising: printing, by a first master plate using a first ink, a first pattern on a first side of a substrate, and wherein the first pattern comprises a first plurality of lines; depositing at least one layer of a conductive material on the first pattern, wherein the layer is deposited by electroless plating; printing, by a second master plate using a second ink, a second pattern on the first side of the first substrate, and wherein the second pattern comprises a second plurality of lines; depositing at least one layer of the conductive material on the second pattern, wherein the layer is deposited by electroless plating; printing, by a third master plate using a third ink, on at least one of the first or the second patterns, a plurality of spacer dots.
In an embodiment, a resistive touch sensor comprising: a first substrate and a second substrate, wherein the first substrate comprises a polarizer film, wherein a first plurality of lines are printed by a first master plate on a first side of the first substrate, and wherein a set of spacers are printed by a second master plate on the first side of the first substrate; wherein the second substrate comprises an optically isotropic transparent film, wherein a second plurality of lines are printed by a third master plate on a first side of the second substrate; wherein the first and the second substrates each comprise an x and a y axis along a surface plane of the first sides that contain the first and the second pluralities of lines; wherein the first plurality of lines is printed along the x-axis of the first substrate, and wherein the second plurality of lines is printed along the y-axis of the second substrate; plating the first and the second plurality of lines by electroless plating; and an adhesive promoting agent, wherein the adhesive promoting agent is disposed between the first side of the first substrate and first side of the second substrate, and wherein the first and the second substrates are assembled to form an x-y grid.
In an embodiment, a display system comprising: a liquid crystal display unit; a resistive touch sensor comprising: an inner and an outer surface, wherein the inner surface is disposed on the second glass substrate; wherein the resistive touch sensor further comprises a first substrate comprising a first set of conductive lines, a polarizer film, a plurality of spacer dots, and a second substrate comprising a second set of conductive lines; and wherein the first and the second set of printed lines are printed using a flexographic printing process and wherein the first and the second set of printed lines are plated with conductive material in an electroless plating process.
For a detailed description of exemplary embodiments of the invention, reference will now be made to the accompanying drawings in which:
The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.
A touch screen display may comprise a liquid crystal display unit and a resistive touch sensor, where the liquid crystal display unit comprises a lighting system, wherein the lighting system comprises a light source, enhancement films, at least one light guide, at least one diffuser plate, a first glass substrate disposed on the light source, a thin film transistor disposed on the first glass substrate and a plurality of liquid crystal cells. In this example, a color filter is disposed on the plurality of liquid crystal cells wherein the color filter comprises a red-green-blue filter and wherein a black matrix is embedded in the RGB filter, and wherein a second glass substrate is disposed on the RGB filter.
In an embodiment, the polymer may absorb dichroic liquid so the iodine ions or dye ions extend into the inside of the polymer. The polymer may be heated and stretched so that it becomes a PVA membrane. The light penetration may be about 5% to view the light penetration under desirable conditions. The other 95% of the light may be refracted, reflected or absorbed by the layers of the film. Polarizers may absorb the light polarized along the long molecular axis and may transmit most of the light polarized in all directions orthogonal to this axis. The absorption rate and the transmittance of the dichroic polarizers may be two factors that affect the brightness of liquid crystal displays (LCDs). Since the mechanical properties, like resistance temperature and humidity, of the polarizer may be poor, films of triacetyl cellulose (TAC) may be used to protect the polarizing layer. The body of iodine polarizing film may be coated with TAC protective film on the upper and lower sides, the protective layers may have a thickness of approximately 200 microns.
Turning back to
In an embodiment (not pictured), a primary three color pattern (red, green and blue) is formed over a black matrix. In the embodiment, this black matrix of chrome or resin may be previously formed on second glass substrate 114, for example, to prevent leakage of backlight and color crosstalk from adjacent pixels, prior to deposition of a substantially transparent conductive touch sensor. In some embodiments, an indium tin oxide film (ITO) is used. A second polarizer 116 may be disposed on top of second glass substrate 114. This second polarizer 116 may also be referred to as an analyzer. The direction of the polarization used by the analyzer may be perpendicular to the direction of polarization of first polarizer film 104.
Resistive touch sensor 120 may be placed over second polarizer 116. The touch sensor 120 and the second polarizer 116 may be separated by a plurality of spacers 118 that may be referred to as spacer dots that also protect touch sensor 120 from electromagnetic interference. In an embodiment, the plurality of spacer dots have a diameter of 1 micron-25 microns and a height of 1 micron-25 microns. Preferably, the plurality of spacer dots have a diameter of 5 microns-10 microns, and a height of 3 microns-5 microns. In an embodiment, indium Tin Oxide (ITO) may be used for touch screen sensor applications as resistive touch sensor 120 as it is optically transparent and is a conductor. In resistive touch screens, when a user touches the screen with a finger or a stylus, the ITO film may be pushed into contact with the ITO glass producing a voltage signal. A processor processes the signal to compute the coordinates (X and Y) of the touch event and process the appropriate response to the touch point. Touch screens may include cover film 122 to protect and isolate the device from environmental conditions and protect against abrasion, normal wear, oxygen and other harmful chemical agents. The protective cover film may be, for example, a polyester (PET) film.
A resistive touch sensor 216 may be disposed on glass substrate 214. Touch sensor 216 may be formed by conductive lines printed on one side of a polarizer film, by means of a roll to roll process. This pattern of lines may be referred to as a conductive microstructural pattern, which may comprise a conductive material patterned on a non-conductive substrate where the conductive material is less than 50 μm wide along the printing plane of the substrate.
Comparing
Flexography is a form of a rotary web letterpress where relief plates are mounted on to a printing cylinder, for example, with double-sided adhesive. These relief plates, which may also be referred to as a master plate or a flexoplate, may be used in conjunction with fast drying, low viscosity solvent, and ink fed from anilox or another two roller inking system. The ink may be combination of monomers, oligomers and/or polymers, metal elements metal elements complexes and/or organometallics in liquid state that is discretely applied over a substrate surface and the anilox roll may be a cylinder used to provide a measured amount of ink to a printing plate. The master plate may be any roll carrying a predefined pattern used to print on any substrate. The anilox roll may be a cylinder used to provide a measured amount of ink to a printing plate. The ink may be, for example, water-based or ultraviolet (UV)-curable inks. In one example, a first roller transfers ink from an ink pan or a metering system to a meter roller or anilox roll. The ink is metered to a uniform thickness when it is transferred from the anilox roller to a plate cylinder. When the substrate moves through the roll-to-roll handling system from the plate cylinder to the impression cylinder, the impression cylinder applies pressure to the plate cylinder which transfers the image on to the relief plate to the substrate. In some embodiments, there may be a fountain roller instead of the plate cylinder and a doctor blade may be used to improve the distribution of ink across the roller.
Flexographic plates may be made from, for example, plastic, rubber, or a photopolymer which may also be referred to as a UV-sensitive polymer. The plates may be made by laser engraving, photomechanical, or photochemical methods. The plates may be purchased or made in accordance with any known method. The preferred flexographic process may be set up as a stack type where one or more stacks of printing stations are arranged vertically on each side of the press frame and each stack has its own plate cylinder which prints using one type of ink and the setup may allow for printing on one or both sides of a substrate. In another embodiment, a central impression cylinder may be used which uses a single impression cylinder mounted in the press frame. As the substrate enters the press, it is in contact with the impression cylinder and the appropriate pattern is printed. Alternatively, an inline flexographic printing process may be utilized in which the printing stations are arranged in a horizontal line and are driven by a common line shaft. In this example, the printing stations may be coupled to curing stations, cutters, folders, or other post-printing processing equipment. Curing may refer to the process of drying, solidifying or fixing any coating or ink imprint, previously applied, on a substrate. Other configurations of the flexo-graphic process may be utilized as well.
In an embodiment, flexo plate sleeves may be used, for example, in an in-the-round (ITR) imaging process. In an ITR process, the photopolymer plate material is processed on a sleeve that will be loaded on to the press, in contrast with the method discussed above where a flat plate may be mounted to a printing cylinder, which may also be referred to as a conventional plate cylinder. The flexo-sleeve may be a continuous sleeve of a photopolymer with a laser ablation mask coating disposed on a surface. In another example, individual pieces of photopolymer may be mounted on a base sleeve with tape and then imaged and processed in the same manner as the sleeve with the laser ablation mask discussed above. Flexo-sleeves may be used in several ways, for example, as carrier rolls for imaged, flat, plates mounted on the surface of the carrier rolls, or as sleeve surfaces that have been directly engraved (in-the-round) with an image. In the example where a sleeve acts solely as a carrier role, printing plates with engraved images may be mounted to the sleeves, which are then installed into the print stations on cylinders. These pre-mounted plates may reduce changeover time since the sleeves can be stored with the plates already mounted to the sleeves. Sleeves are made from various materials, including thermoplastic composites, thermoset composites, and nickel, and may or may not be reinforced with fiber to resist cracking and splitting. Long-run, reusable sleeves that incorporate a foam or cushion base are used for very high-quality printing. In some embodiments, disposable “thin” sleeves, without foam or cushioning, may be used.
In some embodiments, the circuit lines may have a resistivity between 0.005 micro Ohms per square and 500 Ohm per square and response times in a range between nanoseconds and picoseconds. It is understood that “ohms per square” means the square formed by the assembly of the two patterns, wherein one In general, with the above metal configuration, circuits consuming 75% less power (or more in some embodiments) than those using ITO (Indium Tin Oxide) may be achieved. In one particular embodiment the width W of the printed electrodes varies from 5 to 10 microns with a tolerance of +/−10%. The spacing D between the lines may vary from about 1 mm to 5 mm. For optimal optical performance the conductive patterns should approximately match the size and shape of the display's black matrix. Hence, spacing D and width W are functions of the size of the black matrix of the display. Height H may range from about 6 nanometers to about 150 microns. Height h of adhesive promoting agent 608 and the plurality of spacer dots 606 may be 500 nanometers or more, depending on the height H of the conductive lines. In an embodiment, the height of the adhesive promoting agent 608 and the height of the plurality of spacer dots 606 are not the same. Polarizer film 602 and second substrate 610 may have a thickness T between 1 micron and 1 millimeter and a surface energy from 20 dynes per centimeter (D/cm) to 90 D/cm.
Then polarizer film 602 may go through second cleaning system 708. In this particular embodiment second cleaning system 708 may comprise a web cleaner. A web cleaner is any device used in web manufacturing to remove particles from a web or substrate. After these cleaning stages, polarizer film 602 goes through a first printing process where a microscopic pattern is printed on one of the sides of polarizer film 602. The microscopic pattern is imprinted by master plate 710 using UV curable ink that may have a viscosity between 200 and 2000 cps. Further, the microscopic pattern may be formed by lines having a width between 2 and 35 microns. In an embodiment, this pattern may be similar to the first pattern shown in
The amount of ink transferred from master plate 710 to polarizer film 602 may be regulated by high precision metering system 712. The amount of ink transferred may depend on the speed of the process, ink composition, and the shape and dimensions of the plurality of lines that comprise the pattern. The speed of the machine may vary from 20 feet per minute (fpm) to 750 fpm, while 50 fpm to 200 fpm may be suitable for some applications. The ink may contain plating catalysts. The first printing process may be followed by a curing step. The curing may comprise ultraviolet light curing 714 with target intensity from about 0.5 mW/cm2 to about 50 mW/cm2 and wavelength from about 280 nm to about 480 nm, in addition it may comprise oven heating 716 module that applies heat within a temperature range of about 20° C. to about 85° C. After the curing step, a plurality of patterned lines 718 are formed on top of the polarizer film 602.
With a printed microscopic pattern on one side, polarizer film 602 may be exposed to electroless plating 720. In this step a layer of conductive material is deposited on the microscopic pattern. This may be accomplished by submerging first patterned lines 718 of polarizer film 602 into electroless plating at plating station 720 in a tank that contains copper or other conductive material in a liquid state at a temperature range between 20 and 90° C., with 80° C. being applied in some embodiments. Alternatively, the conductive material may comprise at least one of silver (Ag), gold (Au), nickel (Ni), tin (Sn), and Palladium (Pd). The deposition rate is normally about 10 nanometers per minute and deposits the conductive material to a thickness of about 0.001 microns to about 100 microns, depending on the speed of the web and according to the application. This electroless plating process does not require the application of an electrical current and it only plates the patterned areas containing plating catalysts that were previously activated by the exposure to UV radiation during the curing process. The plating bath may include powerful reducing agents, such as borohydride or hypophosphite, which cause the plating to occur. The plating thickness resulting from electroless plating may be more uniform compared to electroplating due to the absence of electric fields. Although electroless plating may be more time consuming than electrolytic plating, electroless plating may be well suited for parts with complex geometries and/or many fine features such as those that may be present in a high resolution conducting pattern. After the plating at plating station 720, first conductive lines 604 are formed on top of polarizer film 602.
Washing process 722 follows electroless plating at plating station 720. After the plating 720, polarizer film 602 may be cleaned by being submerged into a cleaning tank that contains water at room temperature and are then dried at drying station 724 in which polarizer film 602 is dried by the application of air at room temperature. In another embodiment, a passivation step in a pattern spray may be added after the drying step to prevent any dangerous or undesired chemical reaction between the conductive materials and water.
The drying at drying station 724 may be followed by the creation of the plurality of spacer dots 606. A pattern of microstructural spacers is printed on the first side of polarizer film 602. The pattern is printed by second master plate 726 using UV curable ink that may have a viscosity between 200 and 2000 cps. The amount of ink transferred from second master plate 726 to polarizer film 602 is regulated by high precision metering system 728 and depends on the speed of the process, ink composition and patterns shape and dimension. The ink used to print the plurality of spacer dots 606 may consist of organic-inorganic nanocomposites utilizing methyl tetraethylorthosilicate or glycidopropyltrimetoxysilane as network formers hydrolyzed using hydrochloric acid. Silica sols, silica powders, ethyl cellulose and hydroxypropyl may be utilized as additives to adjust viscosity. The ink may also include a commercially available photoinitiator, such as Cyracure, Flexocure or Doublecure, allowing the use of ultraviolet light curing. The plurality of spacer dots 606 may be enhanced optically by nano-particle metal oxides and pigments such as titanium dioxide (TiO2), barium titanium dioxide (BaTiO), silver (Ag), nickel (Ni), molybdenum (Mo) and platinum (Pt). The index of refraction of the dots preferably will match optically the index of refraction of first conductive lines 604. Nano-particles can also be used to adjust the viscosity of the ink. Furthermore, the shrinkage during curing may be reduced by the incorporation of nanoparticle leads to the ink. Following the second printing process polarizer film 602 may go through a second curing step, comprising ultraviolet light curing 730 with an intensity from about 0.5 mW/cm2 to 20 mW/cm2 and/or oven drying 732 at a temperature between 20° C. and 150° C. The plurality of spacer dots 606 may have a radius between 80 microns and 40 microns and a height between 500 nanometers and 15 microns. Subsequently, polarizer film 602 may go through second washing process 734, using known conventional washing techniques, then polarizer film 602 may be dried using air at room temperature in at drying station 736.
In a parallel process, following similar steps, second conductive lines 612 may be created on one side of second substrate 610. This substrate may be an optically isotropic transparent film such as cellulose triacetate, acrylic, or similar polymers. Alternatively, spacer dots may also be printed on second substrate 610 in a similar manner as disclosed above.
When both conductive patterns have been printed and plated, the resistive touch sensor may be assembled. First, a layer of adhesive promoting agent 608 may be applied on a polarizer film 602 surrounding the first plurality of conductive lines 604, having a layer thickness of more than 500 nanometers, in some embodiments. Then second substrate 610 that has the second plurality of conductive lines 612 is bonded to polarizer film 602, in such a way that both conductive patterns are aligned, facing each other and separated by the small gap created by spacer dots 606 and adhesive promoting agent 608. The resulting structure would be an X-Y matrix resistive touch sensor, where each of the intersections of the conductive lines forms a normally open push button switch, as illustrated in
In a parallel process 1232, following steps 1234-1256 which are similar to steps 1206-1228 discussed above, a second component is created. In an embodiment, the second component is created using a second substrate (not pictured). In some embodiments, this second substrate may be an optically isotropic transparent film such as cellulose triacetate, acrylic, or similar polymers. In an embodiment, spacer dots may be printed at printing station 1252 instead of or in addition to the spacer dots printed at printing station 1224.
The first and the second substrate may be assembled at assembly station 1258 to form a resistive touch sensor. In some embodiments, the assembly at assembly station 1258 may proceed as described in
It is understood that the detail drawings and specific examples given describe exemplary embodiments of the present invention and are for the purpose of illustration. The apparatus and method disclosed herein are not limited to the precise details and conditions disclosed. The present method may be applied to electronic devices with touch sensitive features. Such an electronic device may include but is not limited to: a display device, such as a projection device, a computing device, a computer display, a portable media player, etc. As an example the electronic device, such as a display device, may include but is not limited to televisions, monitors and projectors that may be adapted to displays images, including text, graphics, video images, still images, presentations, etc. The following is a non-exhaustive list of exemplary image devices: Cathode ray tubes (CRTs), projectors, flat panel liquid crystal displays (LCDs), LED systems, OLED systems, plasma systems, electroluminescent displays (ELDs), field emissive displays (FEDs).
It also should be understood that numerous modifications may be made to these illustrative embodiments without departing from the spirit and scope of the present invention as defined by the following claims.
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.
The present application claims priority to U.S. Provisional Patent Application No. 61/551,124, filed on Oct. 25, 2011 (Attorney Docket No. 2911-02500); which is hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2012/061766 | 10/25/2012 | WO | 00 | 7/17/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61551124 | Oct 2011 | US |
