MXPA06009131A - Resistive touchscreen with programmable display coversheet - Google Patents

Abstract

A resistive touchscreen (20) having a programmable display (60), such as an emissive display matrix of organic light-emitting diodes, or a reflective electronic paper display, built into the coversheet (26). The touchscreen may be of any resistive type, including 4-wire, 5-wire, and diode 3-wire. A touch/display system is thus provided in which there is little or no degradation of the displayed image due to image transmission through the internal touch sensor components, and in which the internal touch sensor components may be constructed of opaque materials.

Description

RESISTIVE TOUCH SCREEN WITH PROGRAMMABLE VISUALIZER COVER FIELD OF THE INVENTION The present invention relates to touch screens; more particularly, to resistive touch screens with programmable display covers.

BACKGROUND OF THE INVENTION Touch screens are the input device of choice for an increased variety of devices and applications operated by computer. A conventional touch screen is a transparent input device that can sense the two-dimensional position of the touch of an object, such as a finger or a stylus. The touch screens are positioned on display devices, such as cathode ray tube monitors and liquid crystal displays, to form touch-screen systems. For example, touch-display systems are used for applications such as restaurant order entry systems, industrial process control applications, automated counting machines, personal digital assistants (PDAs), interactive museum exhibits, registration machines of airlines, etc. Touch screens have been manufactured using a number of different technologies, such as resistive (eg 4-wire, 5-wire, 9-wire, 3-wire), capacitive, acoustic, and infrared (IR). Resistive touch screens such as the AccuTouch ™ product line from Elo TouchSystems, Inc. of Fremont, Calif., Have been widely accepted for many touch screen applications. On a resistive touch screen, the mechanical pressure of a finger or stylet causes a cover (typically plastic membrane) to flex and make physical contact with a lower substrate (typically glass). The substrate is coated with a resistive layer on which voltage gradients are stimulated. In a 5 wire resistive touch screen, associated electronics can sequentially stimulate gradients both in the X direction and in the Y direction via electrical connections to the four parts of the substrate. The lower part of the cover has a conductive coating which provides an electrical connection between the location of the touch and the electronic voltage sensors. 4-wire resistive touchscreens alternate between stimulating a voltage gradient over the resistive substrate coating and stimulating an orthogonal voltage gradient over the jacket covering to obtain the respective X and Y coordinates. It will be appreciated that the "resistivity" of a material can also be (though inversely) described in terms of its "conductivity"; that is, a material that is described as having a relatively high resistivity can also be described as having a relatively low conductivity. Notably, if the respective substrate and coverings were both perfectly conductive, the touch screen would not work. A significant resistivity (eg, within a range of 100 to 1000 - or even higher - Ohms / square) of the coatings is essential for the generation of the voltage gradients at reasonable levels of energy consumption. Thus, the terms "conductive" and "resistive", as used in the present specification and the appended claims, both refer to the ability to conduct at least some current in response to an applied voltage. It will also be appreciated that, as used herein, the terms "layer" and "coating" refer to functionally similar, if not identical physical structures, and should be considered generally interchangeable in the present specification and appended claims. More details regarding resistive touch screens can be found in U.S. Pat. number 6, 163,313, which is fully incorporated herein by reference. A performance advantage of resistive touchscreens over other touchscreen technologies is its relatively high sensitivity to touch for a passive pointed tip stylus, such as a small plastic stylet, a long fingernail or the corner of a credit card. Also, resistive touch screens consume little to zero energy in the "sleep" or "detection" mode, in which they function as simple on / off membrane switches. The need for energy is only consumed when touches are presented and voltage gradients are generated to coordinate information. In this way, resistive touch screens are energy efficient, making them highly attractive as a touch screen technology for battery-powered devices (eg, portable) devices, such as PDAs. A major disadvantage of resistive touch screens, however, is their degradation of the quality of the image displayed due to the multiple solid / aerial interfaces that the optical image must pass, as well as the optical absorption and haze of the light diffused within multi-layered touch-screen material, and the brightness of ambient light reflecting from the multiple air / solid interfaces or diffused within the various layers of touch-screen material. The use of a degenerate semi-conductor, such as indium tin oxide (ITO), provides means to produce relatively transparent conductive films. However, they still cause refractive losses and significant optical transmission over the displayed image. Additionally, because conductive coatings must be transparent, less expensive and / or better performing, although more opaque, resistive coatings, such as conductive polymers or thin metal layers are not commercially popular for resistive touch screens, and Resistive, completely opaque coatings such as thick metal layers or composites can not be used.

BRIEF DESCRIPTION OF THE INVENTION According to a general aspect of the invention, a resistive touch screen is provided with a cover having a programmable display, that is, a display having an image that can be controlled and changed via electronic signals. Because the cover includes a programmable display, the substrate and internal components (ie "touch sensor") of the touch screen do not need to be transparent. For example, conductive coatings with poor optical transmission properties, eg. , relatively opaque conductive polymers or thin metal layers, can be used. In addition, fully opaque, resistive coatings, such as thicker or composite metal layers, may be used. In one embodiment, the touch screen comprises a substrate having a first conductive region on an upper surface thereof, and a cover having a second conductive region on a lower surface thereof, the lower surface of the cover viewing and spacing from, the upper surface of the substrate. The cover has a programmable display visible from its top surface, the cover (and display) being collectively flexible enough that a force applied to the cover causes the first and second conductive regions to come into electrical contact in a location close to the applied force. The programmable display may comprise a dynamic display, eg, a video display, a static display, eg. , an arrangement of icons, or some combination of them. The programmable display may be an emitter, such as a matrix of organic light emitting diodes ("OLEDs"), or reflectors, such as electronic paper elements, or it may have some sections that are emitting and some that are reflective. Other and more aspects, modalities and characteristics of the invention will be apparent from the following detailed description and the illustrated modalities, which are proposals to demonstrate, but not limit, the invention.

BRIEF DESCRIPTION OF THE FIGURES The figures illustrate the design and utility of embodiments of the invention, in which: Figure 1 is a sectional side view of an exemplary resistive touch screen having a cover with a programmable display; Figure 2 is a partial plan view of a modality of the cover of the touch screen of Figure 1, wherein a matrix of OLEDs forms a programmable emitter display embedded in the cover; and Figure 3 is a sectional side view of an OLED element in the embodiment of Figure 2.

DETAILED DESCRIPTION OF THE ILLUSTRATED MODES Figure 1 illustrates a resistive touch screen 20, which generally comprises a substrate 22 and a cover 26. The touch screen 20 can be any type of resistive touch screen, including but not limited to 4 wire diode , 5 wires, or 3 wires. The substrate 22 has an upper surface 25 with a conductive coating 24 formed thereon. The cover 26 has a lower surface 27 having a conductive coating 28 formed thereon. It will be appreciated that, in alternative embodiments, the upper surface of the substrate 25 and / or lower surface of the cover 27 may be provided with respective conductive / resistive regions through other means than the coatings 24 and 28, such as, for example, by implantation of particles. It will also be appreciated that the various layers of the touch screen 20 are not drawn to scale in the figures, which are for illustrative purposes only. The cover 26 has a surface facing outward (or upward) 38, from which a programmable display 60 is visible. In this way, the touch screen 20 comprises an internal tactile sensor (conductive layers 24 and 28) which is below a programmable external display 60 positioned in register with the touch sensor in such a way that, when the elements displayed by the display 60 are touched, the touch sensor determines the two-dimensional position of the touch on the display 60. As used herein, a programmable display generally refers to a display capable of generating an image that can be controlled and changed via electronic signals. The programmable display 60 may be an emitting display. Alternatively, in modalities specially made for energy sensitive applications, the programmable display 60 may be a reflector display that depends on the reflected ambient light. Either emitter or reflector, the programmable display 60 may be a video display formed by a (traditionally rectangular) arrangement of pixels for the generation of arbitrary images; a static viewer, such as an icon arrangement; or some combination of them. More particularly, the programmable display 60 generally comprises an array (or array) of displayed elements (described in greater detail below) formed or otherwise positioned on a flexible substrate 62 (eg, glass). Optionally, a transparent protective layer 40 (eg, plastic) is superimposed on the display 60. Because a hard-tipped stylet may be damaging the display elements, it may be desirable for the protective layer 40 to be relatively thick (although soft). If desired, the material of the protective layer 40 can be selected to give the cover surface a "paper-like" feel as a writing surface. It may also be desirable to make the replaceable protective top layer 40, eg, a removable liners. The cover 26 is sufficiently flexible, such that a force applied to the upper surface 38, eg, by a finger or a stylet, causes the conductive coating 28 on its lower surface 27 to make electrical contact with the conductive coating 24. of the substrate 22 in a location close to the applied force. As used herein and in the claims, the term "flexible" does not necessarily require that the cover be constructed only of materials that are ordinarily considered as being elastic or deformable, although such properties are possible. What matters is that the component layers of the respective cover (28, 62, 60, 40) collectively have sufficient play or "flexibility" to move easily against the substrate 22 to result in electrical contact of the conductive coatings. respective 28 and 24, without undue application of force being necessary, and without undue stress and wear on the components of the cover that may lead to a failure. It should be readily apparent that this overall flexibility of the cover can be achieved in spite of having certain components of the cover, such as glass layers, made of materials not ordinarily considered as "flexible". A control circuit (not shown) is provided to identify in a conventional manner (depending on the type of resistive touch screen) the two-dimensional coordinates (X and Y) of the location of a force applied to the cover 26, provided that a electrical contact is made between the conductive coatings 24 and 28. In a type of 4 wires, a first voltage gradient is applied to the first conductive region 24 for a first position coordinate measurement, and a second voltage gradient is applied to the second conductive region 28 for a second position coordinate measurement. In a 5-wire type, alternating voltage gradients are applied to the first conductive region 24 for the determination of both the first and second position coordinate measurements. A 3-wire type diode is similar to a 5-wire type, but also includes a plurality of diodes (not shown) connected to the first conductive region 24. The same or separate control circuit is also coupled to the programmable display 60 to operate same. In the illustrated embodiment, a plurality of conventional mechanical (non-conductive) spacer elements 30 are used to maintain an insulating groove 32 between the respective conductive coatings 24 and 28 in the absence of any force being applied to the cover 26. The cover 26 is preferably sufficiently elastic so that it will return to its spaced position relative to the substrate 22 in the absence of any force being applied. It will be apparent that other mechanisms are possible for the maintenance of an electrical insulation of the conductive coatings 24 and 28 in the absence of a force applied to the cover 26. For example, in an alternative embodiment (not shown), the cover 26 can be placed under tension and suspended under the substrate 22, somewhat like a trampoline, so that in the absence of a touch, the electrical insulation of the conductive coatings 24 and 28 be maintained even when spacers 30 are not provided. The touch screen 20 of this mode can be used as a touch / display system in a number of applications. By way of example, the touch screen 20 could be used to support a graphical user interface (GUI), such as those widely used in PDAs and personal computers. To the operating system (not shown), the touch screen 20 and its associated electronic controllers typically function as an input device (i.e., "mouse"), allowing the user to "click" on icons, drag cursors, etc. The operating system can communicate this input information by tapping the application code so that it can respond appropriately, such as by generating or updating a displayed image. For example, an image generated by the display 60 may ask for a user input, and a subsequent image is based at least in part on the user input. By way of example, a displayed image may change in response to the detection of a force on the cover 26, eg, to change from an "unused" mode to a mode in which user inputs may be required and received by the user. the touch screen 20. As with other display applications, associated electronics (not shown) in embodiments of the invention receive information from images of the operating system and generate the appropriate control signals for the display 60. Of course, there is no requirement that the touch-display system of this or any other mode is used with standard operating systems, and many options are available for customized versions of the associated electronics and software. With reference to Figure 2, in one embodiment, the programmable display 60 is an emitting display formed by a matrix of emitting OLEDs 54 embedded in a flexible layer of the display 55. The OLEDs 54 may be prefabricated and then mounted on the substrate 62, or they may be manufactured directly on the substrate 62 as part of the construction of the cover. The OLEDs 54 are preferably thin and flexible enough to flex with the cover 26, while being rigid enough to survive the constant flexing and bumping during use. A possible construction of the OLEDs 54 for use in embodiments of an emitter display of the invention is described in "Flexible Organic LEDs," Weaver et al., Information Display 5 &; 6, pp. 26-29, 2001, which is fully incorporated herein by reference. As it is described in Weaver et al. , flexible OLEDs have been developed by Universal Display Corp., Swing, New Jersey, USA, and are conformable, light weight, thin profile, and have an inherent impact resistance. As shown in Figure 3, the OLEDs 54 generally comprise a thin conductive anode layer 64 on the substrate 62. A set of organic layers 66 having a thickness in the order of 150nm is deposited by vacuum sublimation or another deposition technique. steam on the anode layer 64. A transparent conductive cathode coating 68 is deposited on top of the set of organic layers 66. In one embodiment, the transparent cathode is composed of a thin metal injection contact covered with ITO. As indicated in Weaver et al. , a flexible upper emitting OLED pixel with an area of 5mm2 has enough flexibility that it can be wrapped around a cylindrical body with a radius of curvature as small as approximately 5mm, which is more than enough flexibility needed for a touch screen cover. It may be desired that the substrate 62 be made of a material (or composite materials) that are barriers to moisture and air, such as glass. For example, in one embodiment, the substrate 62 is made of glass and has a thickness of about 200 microns or less. As described in Weaver et al. , OLEDs 54 may alternatively be grown on flexible substrates coated by barriers with optical performance that is comparable to or superior to similar OLEDs manufactured on conventional glass substrates. The OLEDs 54 are further encapsulated in a flexible, non-conductive, transparent polymer material 55. Suitable electrical connections (not shown), such as traces formed on a substrate 62, are provided to form the respective electrical connections from the control circuit (and a source of power) to the various OLEDs 54. It should be appreciated that other types of emitting displays may be used in embodiments of this invention. The displays may be manufactured or mounted on an exterior surface of the cover 26, or otherwise embedded therein, provided that the display is visible from the exterior surface. It will be appreciated that such emitting displays, including the displays using OLEDs, do not necessarily have to be highly flexible, as is often what is expected for a "flexible display", as long as they are thin enough to allow slight deformation necessary for the overall functionality of the touch sensor of the cover 26. In alternative embodiments, the reflective displays - such as "electronic paper" displays - may be used to implement the programmable display 60. As with the emitting displays, such reflective displays may be manufactured or mounted on an exterior surface of the cover 26, or otherwise be embedded therein, as long as the display is visible from the exterior surface. As in the case of the emitting displays, such reflective displays do not need to be highly flexible as long as they are thin enough to allow the slight deformation necessary for the overall functionality of the touch sensor of the cover 26. As used herein, the term "electronic paper" is intended to broadly include any electronically controlled reflector display that can be manufactured in the form of a thin, preferably flexible sheet. As non-limiting examples, there are at least three different reflector display technologies being developed that can be used in programmable display modes 60. One is that developed by Royal Philips Electronics ("Philips") based on "electro-humidity". As the filing date of the present applicationDetailed information on Philips electro-humidity technology can be found using links from www.research.Philips.com/informationcenter/Global/- FArticleDetail.asp? IArticleld = 2817. Such a league is for an article entitled "Video-speed electronic paper based on electrowetting", Hayes et al., Nature, Vol. 425, pp. 383-385, September 25, 2003, which provides a rigorous scientific presentation of the Electrohumidity technology, and which is fully incorporated herein for reference. Another convenient technology of electronic paper is a "electrophoresis" viewer being developed by E ink (www.eink.com). based on a proprietary material that they refer to as an "electronic ink". The main operation is explained on the website http://www.eink.com/technoloqy/index.html. the content of which is fully incorporated herein for reference. Another article, "Flexible active-matrix electronic ink display", Chen et al. , Nature, Vol 423, p. 136, May 8, 2003, which is fully incorporated herein by reference, describes in detail an embodiment of an electronic ink display developed by E ink and suitable for reflector display modes of the present invention. As described in Chen et al., Such a display comprises electronic ink elements formed on a foldable sheet of active array array arrangement. The display is preferably less than 0.3mm thick, has a high pixel density (eg, 160 x 240 pixels) and resolution, eg. , 96 pixels per inch (ca 38 pixels per cm), and can be bent to a radius of curvature as small as 1.5cm without any contrast degradation. Yet another suitable electronic paper technology for use in reflector display embodiments of the invention is an electro-gyroscopic display technology developed at Xerox PARC and promoted by Gyricon Media. (www.qyriconmedia.com), as "SmartPaper ™". The SmartPaper ™ is flexible as traditional paper, and is described in detail on its website http.V / qyriconmedia / SmartPaper.asp, the content of which is fully incorporated herein for reference. Another reflector display technology for use in embodiments of the invention of the programmable display 60 includes several variants of flexible liquid crystal displays ("LCDs"). As an example, according to an article found at www.electronicstimes.com/story/OEG2001 1 108S0004, Omron, Corp. (of Japan) has developed technology used to produce LCDs that can be folded and stored. According to another article published and found at www.eetimes.com/storv/OEG20010829S0065. Philips has developed a cholesteric LCD, 64x64 passive reflective matrix, developed to offer ultra-thin, flexible displays. Also, according to information found at www, creativepro.com/store/news/16653.html?cprose+3-22, Toshiba Corporation has announced that it has developed a long flexible LCD that will be provided for displaying images on curved screens and, eventually, foldable liquid crystal displays. The content of each of the above web links is fully incorporated herein for reference. In this way, thin, flexible displays have been developed in the laboratory, and have the potential to become mass-market products. For example, see "Bending the Rules," on pages 20/24 of March, 2003, Number of Viewer Information, which is fully incorporated herein for reference, Common to all viewers is the need for convenient flexible substrate materials. As noted in this reference, both constructions and polymer including glass films with a thickness of 30 to 150μm have been developed for this purpose.If a display with a large number of individually controlled pixels is desired, this reference notes that suitable active matrix backing planes are required as well as being feasible using amorphous silicon structures as well as organic semiconductors.Despite the nature of the electro-optical imaging elements, many options are available.This particular reference considers LCDs, OLED displays, and electrophoretic displays as candid atos leaders for flexible visualizer technologies.

The detailed description below includes passages that are primarily or exclusively concerned with particular features or aspects of particular embodiments of the invention. It should be understood that this is for clarity and convenience, and that a particular feature may be relevant in more than just the passage in which it is displayed and the modality in which it is described. Similarly, although the various figures and description related herein to specific embodiments of the invention, it is to be understood that where a specific characteristic is disclosed in the context of a particular figure or modality, such a feature may also be used, to the appropriate degree, in the context of another figure or modality, in combination with another characteristic, or with the invention in general.

Claims (18)

1. CLAIMS 1. A touch screen, comprising: a substrate having a first conductive region on an upper surface thereof; and a cover (a) having a second conductive region on a lower surface thereof, the lower deck surface facing and being spaced from the upper surface of the substrate, (b) comprising a programmable display, and (c) being sufficiently flexible that a force applied to the cover causes the first and second conductive region to make electrical contact in a location close to the applied force. The touch screen according to claim 1, characterized in that the cover is sufficiently resilient that, in the absence of any force applied to the cover, there is no electrical contact between the first and second conductive region. The touch screen according to claim 1 or 2, wherein a voltage gradient is applied to the first conductive region for a first position coordinate measurement, and a voltage gradient is applied to the second conductive region for a second position coordinate measurement. The touch screen according to claim 1 or 2, wherein a first voltage gradient is applied to the first conductive region for a first position coordinate measurement and a second voltage gradient is applied to the first conductive region for a second position coordinate measurement, preferably wherein the touch screen further comprises diodes connected to the first conductive region, 5. The touch screen of any of the preceding claims, characterized in that the programmable display is a video display. The touch screen according to claim 1, characterized in that the programmable display is an emitting display. 7. The touch screen according to claim 6, the display comprising one or more organic light emitting diodes ("OLEDs"). 8. The touch screen according to claim 7, the cover comprising a flexible polymer substrate on which one or more OLEDs are manufactured. The touch screen according to claim 7, the cover comprising a flexible glass substrate on which one or more OLEDs are manufactured, preferably wherein the glass substrate has a thickness of about 200 microns or less. The touch screen according to claim 1, wherein the programmable display is a reflector display, preferably wherein the display includes electronic paper. eleven . The touch screen according to claim 1, wherein the top surface of the cover comprises a substantially transparent protective polymer layer, preferably wherein the protective polymer layer is configured to be used as a writing surface or is removable. The touch screen according to claim 1, wherein one or both of the first and second conductive regions comprises an opaque material or a conductive polymer coating. 13. A touch screen, comprising: a substrate having a top surface; a cover having a lower surface and an upper surface, the lower surface of the cover facing the substrate of the upper surface; a first conductive coating provided on the upper surface of the substrate. a second conductive coating provided on the lower surface of the cover; and a programmable display configured to generate images visible from the upper surface of the cover; the cover being flexible enough so that a force applied to the upper surface of the cover causes the first and second conductive coatings to make electrical contact in a location close to the applied force. The touch screen according to claim 13, further comprising a control circuit configured to identify two dimensional coordinates of the location of a force applied to the cover. 15. The touch screen according to claim 13, the display comprising organic light emitting diodes or electronic paper. 16. A touch screen, comprising: an interior touch sensor; and a programmable external display positioned in register with the touch sensor such that, when elements displayed by the display are touched, the touch sensor determines a two-dimensional position of the touch on the display. The touch screen according to claim 16, the touch sensor comprising a substrate having a first conductive region on an outer surface thereof, and a cover having a second conductive region on an inner surface thereof, the inner surface of the cover viewing and being spaced from the outer surface of the substrate, wherein the cover is sufficiently flexible such that a touch to the display causes the conductive regions, first and second, to make electrical contact in a location close to the touch. The touch screen according to claim 17, characterized in that the programmable display is an emitting display or a reflecting display, preferably wherein the programmable display is a video display. SUMMARY A resistive touch screen (20) having a programmable display (60), such as an organic light emitting diode emitter display array, or a reflective electronic paper display, formed on the cover (26). The touch screen can be of any resistive type, including 4 wire, 5 wire and 3 wire. A touch / display system is provided in this manner in which there is little or no degradation of the displayed image due to image transmission through the components of the internal touch sensor, and in which internal touch sensor components they can be constructed of opaque materials. 1/1 FIG. 3 62