WO2008133432A1

WO2008133432A1 - The signal applying structure for touch screen with unified window

Info

Publication number: WO2008133432A1
Application number: PCT/KR2008/002288
Authority: WO
Inventors: Young-Soo Ahn; Seung-Duc Ahn; Ok-Hwa Chun
Original assignee: Young-Soo Ahn; Seung-Duc Ahn; Ok-Hwa Chun
Priority date: 2007-04-30
Filing date: 2008-04-23
Publication date: 2008-11-06
Also published as: KR100897973B1; KR20080096881A

Abstract

Provided is a signal-applying structure of a window- integrated touch screen. The touch screen in accordance with the present invention includes a structure having a pad electrode for applying electrical signals to a lower plate and a through-hole for the passage-through of FPC, for easy integration of a touch screen having a position and character recognition function into a window used in a front part of a mobile device such as mobile phone, so as to protect a flat panel display and maintain flatness of the external appearance of a device.

Description

[DESCRIPTION] [Invention Tit Ie]

THE SIGNAL APPLYING STRUCTURE FOR TOUCH SCREEN WITH UNIFIED WINDOW [Technical Field]

<i> The present invention relates to a window-integrated touch screen. More specifically, the present invention relates to a signal-applying structure which is sought for the realization of a window-integrated touch screen maintaining the flatness of a window to have no difference in the appearance upon comparing with a window of a conventional mobile device without touch screen function. [Background Art]

<2> With recent development and common propagation of graphic user interface (GUI) systems, touch screen devices with simple and easy input function are gaining popularity among users.

<3> Touch technologies differ in the way each detects a touch. The touch screen may be broadly categorized into a resistive touch screen, a capacitive touch screen, an optical touch screen, a surface acoustic wave touch screen, an electromagnetic touch screen, a vector force-based touch screen, etc., each of which has strengths and weaknesses.

<4> Hereinafter, a brief description will be given of individual types of touch screens.

<5> The capacitive touch type is based on determination of the touch position coordinates by sensing the flow of micro-current in response to capacitance changes occurring between a sensor electrode and a user's finger. This type suffers from a disadvantage of susceptibility to noise signals, but has advantages such as high environmental reliability and easy changeability of mechanical reliability by the modification of an upper protective film.

<6> The optical type is based on determination of the touch position coordinates which involves installation of pairs of light-emitting parts and light-receiving parts opposite to each other at x- and y-axis edges of a display substrate and determination of the touch position using a signal of the light-receiving part detected when a user's finger or any pointing means touches a display screen to result in interception of light. In terms of a principle, the optical type requires no use of a film for touch recognition, which in turn results in transmissivity of 100%. As a result, this type of touch screen does not involve adverse problems such as reflection, lowering of brightness and optical changes, which usually occur upon attachment of a different type of a touch screen. However, this type has a limitation in enhancement of resolution, because the resolution capable of recognizing the touch position coordinates is determined by array spacing between devices of the light-emitting and light-receiving parts.

<7> The surface acoustic wave type, also similar to the optical sensor type, is a touch screen which is based on position coordinate determination of the touch point when the acoustic wave path between an acoustic wave generation device and an acoustic wave recognition device is intercepted. Unfortunately, this type of touch screen is disadvantageousIy vulnerable Io acoustic noise such as factory noise.

<8> The electromagnetic type is a touch screen taking advantage of a magnet and a phenomenon of the electromotive force generation on the basis of Faraday's law, which involves calculation of touch position coordinates by measuring an amount of the current flowing through the coil at each corresponding position. This touch screen type is inconvenient in that it requires use of a dedicated input pen due to the need for application of AC signals to the coi 1.

<9> The vector force type is based on determination of the touch position coordinates by installing a capacitive sensor for sensing pressure-dependent deformation on the lower main part of a display, sensing pressure of each region produced when the display is pressed by a user's finger or any means, and calculating the corresponding pressure as a function of vector. This type has shortcomings in that the calculation rate is determined by the system specification and minute position changes cannot be sensed. <io> The resistive type is a touch screen which is comprised of two upper and lower substrates covered with transparent conductive layers and is operated in a manner that two conductive layers come in contact when the screen is touched by a pointing means, such as a finger or a pen-like stylus, and then two-dimensional coordinate information is generated by the voltages produced at the touch location. The resistive touch screen is widely used due to having relatively easy real izabi 1 ity and superior performance as compared to other currently available touch screen types, even though it suffers from disadvantages connected with poor mechanical and environmental reliability because a film-like substrate is largely used as a material for an upper substrate.

<ii> FIG. 1 is a schematic diagram showing an overall structure of a common mobile device.

<i2> The mobile device shown in FIG. 1 is a conventional mobile phone without touch screen function. In this device, number and character input is performed using a lower keypad and confirmation of input is done through a window 2 by the means of a screen of a flat panel display device which is provided at a rear part of the window 2.

<13> The window 2 covers an upper front surface of the flat panel display and is largely formed of polycarbonate (PC), acrylic resin or tempered glass. In order to maintain a front part of the window 2 as a flat structure, a company or product logo is printed on the rear part of the window 2.

<14> FIG. 2 is a cross-sectional view of a mobile device using a conventional resistive touch screen.

<15> As shown in FIG. 2, a conventional resistive touch screen 4 is fixed on a flat panel display device 5 using a double-sided adhesive tape 11, a soft cushion 6 or the like is filled between a frame 3 of the mobile device and the touch screen 4, and the flat panel display 5 and the touch screen 4 are then fixed.

<i6> The resistive touch screen 4 is comprised of an upper plate 7 and a lower plate 9. Below the upper plate 7 is provided a thin transparent conductive film. Above the lower plate 9 is provided a thin transparent conductive film. Between the upper plate 7 and the lower plate 9 are provided dot spacers 8 for insulation. Further, a double-sided adhesive tape 10 is provided for mechanical fixing of the upper plate 7 and the lower plate 9.

<i7> As shown in FIG. 2, a flexible printed cable (FPC) 12 is employed for application of external signals to the resistive touch screen 4. The FPC 12 is electrically connected to an outer part of the resistive touch screen 4 via a bonding process using an anisotropic conductive material. As the FPC 12 is connected through the outer part of the resistive touch screen 4, the FPC 12 is inevitably connected to an external system along a side of the resistive touch screen 4. As a consequence, such a configuration is a direct obstacle to integration of the frame 3 and the resistive touch screen 4. Further, it is basically impossible to prevent the entrance of moisture and dust from the outside, because the soft cushion 6 or the like is filled between the frame 3 and the resistive touch screen 4. The invasion of such foreign materials may be responsible for internal contamination and malfunction of the device.

<18> FIG. 3 is a cross-sectional view of a mobile device using a window- integrated touch screen.

<19> In order to achieve the desired flatness without a step difference with a frame 19 by integration of a resistive touch screen 13 and a window 2 of a mobile device, it is necessary that an FPC 14 is connected externally through the inside of the resistive touch screen 13, as shown in FIG. 3. When the FPC 14 is connected along a side of the resistive touch screen 13, an aperture is formed between the frame 19 and the resistive touch screen 13, which in turn results in unavoidable contamination of the device due to the entrance of moisture and dust from the outside.

<20> Therefore, in order to secure passage of the FPC 14 through the inside of the touch screen 13, it is necessary that a lower plate 17 is provided with an electrical connection means using a through-hole or the like.

<2i> FIG. 4 is a structural view of a touch screen for the realization of a conventional window-integrated touch screen. <22> The structure of FIG. 4 shows a representative drawing of Japanese Unexamined Patent Publication (Kokai) No. 2006-178871. As discussed before, in order to realize a window-integrated touch screen without a step between a touch screen and a frame of a mobile device, a contact area of the FPC 13 for applying of a signal should be electrically connected through the inside of a lower plate 16, as illustrated in FIG. 3.

<23> More specifically, the conventional structure employed a connector 20 to achieve the electrical passage-through of FPC through the inside of the lower plate 16. In order to use the connector 20 as a medium for the electrical passage-through of FPC, an outer part including corners is cut from the inside of the lower plate 16 and the connector 20 is then fitted into the cut-out of the lower plate 16. Thereafter, an upper plate 14 printed with a company logo or the like is brought into electrical contact with an upper part of the connector 20, and a lower part of the connector 20 is brought into electrical contact with the FPC 13, thereby resulting in a structure where the FPC 13 electrically passes through the inside of the lower plate 16.

<24> FIG. 5 is a structural view of a connector of a touch screen for the realization of a conventional window-integrated touch screen.

<25> Specifically referring to the conventional touch screen configuration disclosed in Japanese Unexamined Patent Publication (Kokai) No. 2006-178871, the connector 20 has a structure where electrical connection of the FPC 13 is made by installation of a through-hole electrode 2Of between a contact electrode 2Od and a contact electrode 2Og, with the electrode 2Od being in contact with the upper plate 14 and the electrode 2Og being in contact with the FPC 13.

<26> FIG. 6 is a cross-sectional view of a signal-applying structure of a touch screen for the realization of a conventional window-integrated touch screen.

<27> As shown in FIG. 6, an anisotropic conductive material 22 containing conductive material-coated conductive balls 22' is employed for electrical connection of the connector 20 containing the through-hole electrode 2Of to a pad electrode 21f disposed below the upper plate 14.

<28> The electrical connection using an anisotropic conductive material generally requires application of pressure and heat. Because a film-like material, such as polyethylene terephthalate (PET), polycarbonate (PC), and acrylic resin, is currently largely used as a material for the upper plate 14 of the resistive touch screen, surface deformation of the upper plate 14 takes place when a bonding process involving application of heat and pressure is applied between the upper plate 14 and the connector 20. For this reason, it is unfortunately difficult to secure and maintain a stepless (flat) surface between the frame 18 and the upper plate 14 of the window-integrated touch screen.

<29> Even though surface deformation of the upper plate 14 is prevented with modification of process conditions, it is impossible to maintain the smooth surface as the upper plate 14 undergoes deformation when strain is continuously and directly imposed to the upper plate 14 by the FPC 13.

[Disclosure] [Technical Problem]

<30> Therefore, the present invention has been made in view of the above problems associated with the deformation of an upper plate which occurs upon attachment of the upper plate to a connector for applying a signal in accordance with a conventional art, and it is an object of the present invention to provide a window-integrated touch screen through attachment of a flexible printed cable (FPC) for applying a signal to a lower plate, whereby deformation of the upper plate is prevented which is likely to occur during a manufacturing process and the smooth flatness of a mobile device is maintained. [Technical Solution]

<3i> In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a window-integrated touch screen, comprising: <32> an upper plate having a transparent conductive film formed on a lower part thereof and a lower plate having a transparent conductive film formed on an upper part thereof! <33> potential compensation electrodes for producing potential distribution for determining of position coordinates and formed on a lower part of the transparent conductive film of the upper plate and an upper part of the transparent conductive film of the lower plate; <34> pad electrodes for applying electrical signals to the potential compensation electrodes of the lower plate and formed on the lower plate; and <35> a through-hole of the lower plate for the passage-through of an FPC applying external electrical signals to the pad electrodes of the lower plate; <36> wherein the FPC for applying the external electrical signals to the pad electrodes is connected through the through-hole to the pad electrodes.

[Advantageous Effects]

<38> As apparent from the above description, the present invention enables previous prevention of surface appearance defects such as non-flatness of the film arising from heat and/or pressure-induced deformation of an upper film as shown in conventional art, through the attachment of a signal-applying FPC to a lower plate out of two upper and lower substrates. [Description of Drawings]

<39> FIG. 1 is a schematic diagram showing an overall structure of a common mobile device!

<40> FIG. 2 is a cross-sectional view of a mobile device using a conventional resistive touch screen;

<4i> FIG. 3 is a cross-sectional view of a mobile device using a window- integrated touch screen;

<42> FIG. 4 is a structural view of a touch screen for the realization of a conventional window-integrated touch screen!

<43> FIG. 5 is a structural view of a connector of a touch screen for the realization of a conventional window-integrated touch screen;

<44> FIG. 6 is a cross-sectional view of a signal-applying structure of a touch screen for the realization of a conventional window-integrated touch screen;

<45> FIG. 7 is a structural view of a first embodiment of a window- integrated touch screen in accordance with the present invention;

<46> FIG. 8 is a structural view of a second embodiment of a window- integrated touch screen in accordance with the present invention;

<47> FIG. 9 is a cross-sectional view of a signal-applying structure of a window-integrated touch screen in accordance with the present invention;

<48> FIG. 10 is a cross-sectional view of a lower plate of a first embodiment of a window-integrated touch screen in accordance with the present invention; and

<49> FIG. 11 is a cross-sectional view of a lower plate of a second embodiment of a window-integrated touch screen in accordance with the present invention. [Best Mode] <50> Hereinafter, the preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. <5i> FIG. 7 shows a first embodiment of a window-integrated touch screen in accordance with the present invention. <52> The window-integrated touch screen comprises: <53> an upper plate 23 having a transparent conductive film formed on a lower part thereof and a lower plate 24 having a transparent conductive film formed on an upper part thereof; <54> potential compensation electrodes 25a' ,25b' ,25c' ,25d' for producing potential distribution for determining of position coordinates and formed on a lower part of the transparent conductive film of the upper plate 23 and an upper part of the transparent conductive film of the lower plate 24; <55> pad electrodes 25a,25b,25c ,25d for applying electrical signals to the potential compensation electrodes 25b' ,25d' of the lower plate 24 and formed on the lower plate 24; and <56> a through-hole 33 of the lower plate 24 for the passage-through of an

FPC 26 applying external electrical signals to the pad electrodes

25a,25b,25c,25d of the lower plate 24; <57> wherein the FPC 26 for applying the external electrical signals to the pad electrodes 25a,25b,25c,25d is connected through the through-hole 33 to the pad electrodes 25a,25b,25c,25d. <58> An electrical signal connection between the potential compensation electrodes 25a',25c' of the upper plate 23 and the pad electrodes 25a,25c of the lower plate 24 is made through contact holes 27 between wiring electrodes extending from the pad electrodes 25a,25c. <59> A means for an electrical signal connection employs a conductive paste. <60> Examples of the conductive paste may include conductive silver paste and conductive carbon paste. <6i> The pad electrodes 25a,25b,25c,25d of the lower plate 24 are formed in the outer region, and the through-hole 33 of the lower plate 24 is formed between the pad electrodes 25a,25b,25c,25d and the active area 37. This is intended for easy cutting of the outer region upon a subsequent cell cutting process, by designing a direction of an end of the FPC 26 to face toward the active area 37.

<62> Using an adhesive, a film printed with the company or product logo is attached to an entire upper surface of the upper plate 23.

<63> Further, an anti-scratch protective film may be further attached to the company or product logo-printed film attached to the upper part of the upper plate 23.

<64> FIG. 8 shows a second embodiment of a window-integrated touch screen in accordance with the present invention.

<65> Upon comparing with the first embodiment, the second embodiment exhibits a different structure wherein a through-hole 33 for the passage- through of the FPC 26 is installed in an outer region of the lower plate 24, and pad electrodes 35 of the lower plate 24 are formed between the through- hole 33 and the active area 37. Such a different configuration enables efficient use of the space available.

<66> FIG. 9 is a cross-sectional view of a signal-applying structure of a window-integrated touch screen in accordance with the present invention.

<67> The window-integrated touch screen comprises:

<68> an upper plate 23 having a transparent conductive film 32 formed on a lower part thereof and a lower plate 24 having a transparent conductive film 28 formed on an upper part thereof;

<69> potential compensation electrodes 25a' ,25b¹ ,25c' ,25d' for producing potential distribution for determining of position coordinates and formed on a lower part of the transparent conductive film of the upper plate 23 and an upper part of the transparent conductive film of the lower plate 24;

<70> pad electrodes 25a,25b,25c,25d for applying electrical signals to the potential compensation electrodes 25b' ,25d' of the lower plate 24 and formed on the lower plate 24; and <7i> a through-hole 33 of the lower plate 24 for the passage-through of an

FPC 26 applying external electrical signals to the pad electrodes

25a,25b,25c,25d of the lower plate 24; <72> wherein the FPC 26 for applying the external electrical signals to the pad electrodes 25a,25b,25c,25d is connected through the through-hole 33 to the pad electrodes 25a,25b,25c,25d, and <73> a double-sided tape or adhesive is used for mechanical bonding of the upper plate 23 to the lower plate 24. <74> In order to prevent the invasion of foreign materials such as moisture and dust into the active area 37, a partition wall 34 of a double-sided tape or adhesive is formed around the through-hole 33. <75> Electrical connection between the FPC 26 for application of external signals to the inside and the pad electrode 25c is done using an anisotropic conductive material 29. <76> For simultaneous realization of other additional functions apart from the touch screen function, it may be possible to form a plurality of through holes 33, FPCs 26 and pad electrodes 25 for realization of such additional functions. <77> The position and dimension of the pad electrode 25 and through-hole 33 may vary if necessary. <78> FIG. 10 shows a cross-sectional view of a lower plate of a first embodiment of a window-integrated touch screen in accordance with the present invention. <79> Referring to FIG. 10, there is exemplified a lower plate 24 formed of a single material in order to protect a flat panel display device and maintain the desired flatness of the external appearance of the device. <80> FIG. 11 shows a cross-sectional view of a lower plate of a second embodiment of a window-integrated touch screen in accordance with the present invention. <8i> Referring now to FIG. 11, there is exemplified a lower plate 24 which is formed of one or a plurality of glass or plastic film substrates.

<82> Further, the window-integrated touch screen in accordance with the present invention has a broad spectrum of electronic applications such as mobile phones, personal digital assistants (PDAs), navigation systems, internet phones, web pads, point of sales (POS) terminals, office monitors, game monitors, industrial monitors, etc. [Industrial Applicability]

<83> As apparent from the above description, the present invention enables previous prevention of surface appearance defects such as non-flatness of the film arising from heat and/or pressure-induced deformation of an upper film as shown in conventional art, through the attachment of a signal-applying FPC to a lower plate out of two upper and lower substrates. Further, formation of a through-hole inside the lower plate and the consequent passage-through of FPC therethrough provide easy input of signals, by attachment of the resulting structure to window-bearing equipment so as to protect a flat panel display such as mobile device and maintain a high degree of flatness of the external appearance of the device.

<84> Further, the present invention enables input of signals using only a window-integrated touch screen device, simultaneously with removal of a conventional keypad from the mobile device. Therefore, it is possible to overcome the problem of a limited size of a flat panel display device that can be applied to a mobile device conventionally by a keypad, thus providing the feasibility to increase a display screen size of the mobile device.

<85> Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[CLAIMS] [Claim 1]

<87> A window-integrated touch screen, comprising: <88> an upper plate having a transparent conductive film formed on a lower part thereof and a lower plate having a transparent conductive film formed on an upper part thereof; <89> potential compensation electrodes for producing potential distribution for determining of position coordinates and formed on a lower part of the transparent conductive film of the upper plate and an upper part of the transparent conductive film of the lower plate; <90> pad electrodes for applying electrical signals to the potential compensation electrodes of the lower plate and formed on the lower plate! and <9i> a through-hole of the lower plate for the passage-through of an FPC applying external electrical signals to the pad electrodes of the lower plate! <92> wherein the FPC for applying the external electrical signals to the pad electrodes is connected through the through-hole to the pad electrodes.

[Claim 2] <93> The touch screen according to claim 1, wherein an electrical signal connection between the potential compensation electrodes of the upper plate and the pad electrodes of the lower plate is made through contact holes between wiring electrodes extending from the pad electrodes.

[Claim 3] <94> The touch screen according to claim 2, wherein a means for an electrical signal connection employs a conductive paste.

[Claim 4] <95> The touch screen according to claim 3, wherein the conductive paste is a conductive silver paste or conductive carbon paste.

[Claim 5] <96> The touch screen according to claim 1, wherein the pad electrodes of the lower plate are formed in an outer region thereof and the through-hole of the lower plate is formed between the pad electrodes and the active area.

[Claim 6]

<97> The touch screen according to claim 1, wherein a through-hole of the lower plate is formed in an outer region thereof, and pad electrodes of the lower plate are formed between the through-hole and the active area.

[Claim 7]

<98> The touch screen according to claim 1, wherein a film printed with a company or product logo is adhesively attached to an entire upper surface of the upper plate.

[Claim 8]

<99> The touch screen according to claim 1, wherein an anti-scratch protective film is attached to the company or product logo printed on the upper part of the upper plate.

[Claim 9]

<ioo> The touch screen according to claim 1, wherein mechanical bonding of the upper plate to the lower plate is carried out using a double-sided tape or adhesive.

[Claim 10]

<ioi> The touch screen according to claim 9, wherein a partition wall of a double- sided tape or adhesive is formed around the through-hole to prevent the invasion of a foreign material such as moisture or dust into the active area.

[Claim 11]

<iO2> The touch screen according to claim 1, wherein a plurality of through-holes, FPCs and pad electrodes for realization of other additional functions are formed for simultaneous realization of other additional functions in addition to the touch screen function.

[Claim 12]

<iO3> The touch screen according to claim 1, wherein the lower plate is formed of one or a plurality of glass or plastic film substrates.

[Claim 13] <iO4> An electronic equipment comprising the window-integrated touch screen of any one of claims 1 to 12.