Abstract:
A touch screen system includes a touch panel to input image signals, a touch controller to drive the touch panel, an extension between the touch panel and the touch controller, and an anisotropic conductive film electrically interconnecting the extension to the touch controller.

Description:
The present invention claims the benefit of Korean Patent Application Nos. P2002-71681 and P2002-72353 filed in Korea on Nov. 18, 2002 and Nov. 20, 2002, respectively, which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a touch panel system, and more particularly, to a touch panel system for a liquid crystal display (LCD) device. 
     2. Discussion of the Related Art 
     Presently, liquid crystal display (LCD) devices are commonly used because of their ability to produce high quality images, as well as their thin profile, light weight, and low power consumption. Liquid crystal module (LCM) devices are used for displaying video signals input from external sources, such as LCD panels, and commonly include polarizing plates, power sources, such as backlight devices, and light-guiding plates. The LCD panels include upper and lower glass substrates, and liquid crystal material injected between the upper and lower glass substrates. In addition, the polarizing plates are formed on lower and upper surfaces of the LCD panel for polarizing light irradiated onto the LCD panel using the backlight device. Moreover, a printed circuit board (PCB) is provided below a main support at a rear of the LCM device, and a drive integrated circuit (D-IC) is provided on the PCB to drive switching devices (i.e., thin film transistors) of the LCM device. Accordingly, the LCM device is electrically connected to the PCB using a tape carrier package (TCP) so that the video signals of the D-IC are transmitted to the LCM device. Furthermore, a digitizer is provided in the LCD device to display images on a screen and to input electric graphic image signals thereon. The digitizer is commonly referred to as an electric graphic input panel (EGIP) or a touch panel. Due to rapid development of LCD technology, it is possible to perform graphic image work that requires high resolution on the LCD device, whereby the digitizer is used as an input device of a notebook computer. 
       FIG. 1  is a schematic cross sectional view of a touch panel according to the related art. In  FIG. 1 , transparent ITO electrodes  3  and  4  are formed on opposing surfaces of two polyethylene terephtalate (PET) films  1  and  2  at a predetermined interval, wherein the two PET films  1  and  2  are bonded to each other using an insulating adhesive. Subsequently, a polyvinyl alcohol (PVA) film  5  is formed below the lower PET film  2  for polarizing light, and a triacetyl cellulose (TAC) film is formed below the PVA film  5  for protecting the PVA film  5  from humidity. In addition, a silver (A/G) layer is formed on the upper PET film  1 . 
     An operation of the touch panel, which is categorized as a 4-line resistive-type touch panel, includes supplying a voltage to one transparent electrode along an X-axis direction, and supplying a voltage to another transparent electrode along a Y-axis direction. For example, a voltage is supplied to an upper transparent electrode  3  along the X-axis direction, and a voltage is supplied to a lower transparent electrode  4  along the Y-axis direction. Accordingly, signals are respectively supplied to the X-axis and the Y-axis in order to detect a location of a touching point in order to read the signals twice. For example, when the voltage is supplied to the upper transparent electrode  3  along the X-axis direction, the upper and lower transparent electrodes  3  and  4  contact each other at a predetermined portion, and a voltage value of the X-axis location is read through the lower transparent electrode  4 . Similarly, when the voltage is supplied to the lower transparent electrode  4  along the Y-axis direction, the upper and lower transparent electrodes  3  and  4  contact each other at a predetermined portion, and a voltage value of the Y-axis location is read through the upper transparent electrode  3 . Accordingly, the upper and lower transparent electrodes  3  and  4  have predetermined resistance values, so that the voltage value varies in accordance with a contact location of the upper and lower transparent electrodes  3  and  4 . Thus, X-axis and Y-axis voltage values are input to a controller, whereby the controller detects coordinates of the touching point according to the X-axis and the Y-axis values. 
     When a predetermined portion of the upper substrate is touched with a finger or a pen, the upper and lower transparent electrodes  3  and  4  contact each other at the predetermined portion. Accordingly, the voltage values, which vary by the resistance value of the touching point, is output. For example, in order to read the voltage values that vary by the resistance value of the touching point, electrodes and lines for supplying the voltage to the upper and lower transparent electrodes  3  and  4  is necessary in order to read the voltage values. 
       FIG. 2  is a plan view of a connection structure between an extension of a touch panel and a controller according to the related art. In  FIG. 2 , a touch panel  9  includes two silver (A/G) electrodes  12  formed along left and right sides of an upper PET film  1  along the X-axis direction, and two A/G electrodes  11  formed along upper and lower sides of a lower PET film  2  along the Y-axis direction. Accordingly, the A/G electrodes  11  and  12  are formed within a dead space region of 2 μm to 3 μm along one direction of the touch panel  9 . Moreover, a size of the touch panel  9  corresponds to sizes of an upper substrate of the LCD panel, wherein electrode lines of the touch panel  9  are formed in a 4-line resistive-type configuration. 
     In order to operate the 4-line resistive-type touch panel, interconnect of the touch panel  9 , a touch controller  23 , and a computer (i.e., CPU) using signal lines is required. A device in which the touch panel  9  and the touch controller  23  are connected to each other is referred to as a touch screen assembly. The touch controller  23  switches voltages and output signals provided to the upper and lower substrates of the touch panel  9 , and receives input location information as electric signals. Then, the touch controller  23  converts the electric signal from analog signals to digital data, and transmits the digital data to the computer. Accordingly, the touch controller  23  is positioned separately from the LCD device, which is integrated with the touch panel, i.e, the touch controller  23  is positioned outside of the LCD device. 
     With the creation of ever smaller LCD devices having thin profiles and light weight to improve portability, integration of the LCD device with the touch controller is desired. For example, the touch controller can be mounted inside the LCD device, and the touch controller may be provided as a chip-type device positioned at rear of the LCM device. 
     In  FIG. 2 , the A/G electrodes  11  and  12  and conductive lines  13   a,    13   b,    13   c,  and  13   d  transmit and read the electric signals, and are formed within the dead space region of the touch panel  9 . In addition, an extension of one of four sides of the touch panel  9  provides a connection part  15  that include end portions of the conductive lines  13   a,    13   b,    13   c,  and  13   d.  A flexible printed circuit board (FPCB)  16  is connected to the end portions of the conductive lines  13   a,    13   b,    13   c,  and  13   d  at the connection part  15 . The FPCB  16  is used for electrically connecting the conductive lines  13   a,    13   b,    13   c,  and  13   d  of the A/G electrodes  11  and  12  of the touch panel  9  to the touch controller  23 . 
     When the FPCB  16  of the touch panel  9  is connected to the touch controller  23 , an FPCB connector  20  is mounted within the controller  23  so that a connection part  17  of the FPCB  16  is inserted into the FPCB connector  20 , thereby electrically interconnecting the A/G electrodes  11  and  12  of the touch panel  9  to the touch controller  23 . Since the FPCB  16  is formed of soft material(s), a stiffener is provided with the connection part  17  of the FPCB  16  for easy insertion of the connection part  17  of the FPCB  16  to the FPCB connector  20 . Accordingly, the signals output from the 4-line electrodes (A/G electrodes  11  and  12 ) of the touch panel  9  are transmitted to the touch controller  23  using the FPCB  16  that is inserted into the FPCB connector  20  of the touch controller  23 , thereby electrically interconnecting the touch panel  9  to the touch controller  23 . 
     However, the signal connection structure between the touch panel and the touch controller according to the present invention has the following disadvantages. First, since the FPCB  16  of the touch panel  9  is electrically connected to the touch controller  23  by the FPCB connector  20 , the FPCB connector  20  is thicker than IC chips below the LCM, whereby a total thickness of the entire interconnection system becomes thick. Thus, obtaining a thin profile and light weight of the LCD device is not achieved. Second, in order to connect the FPCB  16  of the touch panel  9  to the touch controller  23 , the FPCB connector  20  is required, thereby increasing manufacturing costs. Third, when connecting the signal lines of the FPCB  16  to the FPCB connector  20 , a connection failure may be generated. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a touch screen system and display device using a touch screen system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide a touch screen system having a signal connection structure between a touch panel and a touch controller for obtaining a thin profile and light weight device. 
     Another object of the present invention is to provide a display device having a touch screen system having a signal connection structure between a touch panel and a touch controller for obtaining a thin profile and light weight device. 
     Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, a touch screen system includes a touch panel to input image signals, a touch controller to drive the touch panel, an extension between the touch panel and the touch controller, and an anisotropic conductive film electrically interconnecting the extension to the touch controller. 
     In another aspect, a touch screen system includes a touch panel to input image signals, a touch controller to drive the touch panel, and an extension having a plurality of signal lines to transmit electrical signals between the touch panel and the touch controller, wherein the extension includes a plurality of end portions that correspond to a total number of the signal lines connected to the touch controller. 
     In another aspect, a touch screen system includes a touch panel having a plurality of electrodes, a touch controller having a plurality of contact pads, and an extension having a first portion physically connected to an end region of the touch panel, a second portion electrically connected to the touch controller, and a third portion disposed between the first and second portions, wherein the second portion of the extension includes a plurality of individual end portions electrically connected to the plurality of contact pads. 
     In another aspect, a liquid crystal display device includes a liquid crystal module, a touch controller provided in a touch controller area at a first edge of the liquid crystal module, a plurality of data driver integrated circuits provide along a second edge of the liquid crystal module within a data driver area, a plurality of gate driver integrated circuits provided along a third edge of the liquid crystal module within a gate driver area, and an extension provided along the data driver area into the touch controller area. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is a schematic cross sectional view of a touch panel according to the related art; 
         FIG. 2  is a plan view of a connection structure between an extension of a touch panel and a controller according to the related art; 
         FIG. 3  is a plan view of an exemplary signal connection structure between an extension and controller connection part according to the present invention; 
         FIG. 4  is a perspective view of an exemplary anisotropic conductive adhesive according to the present invention; 
         FIG. 5  is a cross sectional view of an exemplary extension and controller connection part according to the present invention; 
         FIG. 6A  is a plan view of another exemplary connection structure between an extension of a touch panel and a controller according to the present invention; 
         FIG. 6B  is an enlarged view of “A” of  FIG. 6A  according to the present invention; 
         FIG. 6C  is a cross sectional view along I-I′ of  FIG. 6A  according to the present invention; 
         FIG. 7A  is a cross sectional view along II-II′ of  FIG. 6B  according to the present invention; 
         FIG. 7B  is a cross sectional view along III-III′ of  FIG. 6B  according to the present invention; 
         FIG. 8A  is a plan view of an exemplary connection structure between an extension and controller according to the present invention; 
         FIG. 8B  is a cross sectional view along IV-IV′ of  FIG. 8A  according to the present invention; and 
         FIG. 9  is a plan view of an exemplary touch controller according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     A touch screen assembly according to the present invention will be described with reference to the accompanying drawings. 
       FIG. 3  is a plan view of an exemplary signal connection structure between an extension and controller connection part according to the present invention. In  FIG. 3 , a plurality of connection pads  22  of a touch controller  23  may be formed on a PCB substrate having the touch controller  23  contained therein, and an anisotropic conductive film (ACF)  25  may be formed on an upper surface of the connection pads  22 . In addition, an extension  16  may be provided to be connected to a touch panel, which may be similar to the touch panel  9  (of  FIG. 2 ), and may be formed on the ACF  25 . Accordingly, a plurality of signal lines  18  formed on the extension  16  may be connected to the connection pads  22 . Thus, the signal lines  18  of a connection part  17  of the extension  16  may be aligned to correspond to the connection pads  22 . The ACF  25  may include plastic material(s) coated with metal material(s). Alternatively, the ACF  25  may include a film upon which conductive particles, such as metal particles, are scattered, thereby simultaneously providing electric signal connection and adhesion. 
       FIG. 4  is a perspective view of an exemplary anisotropic conductive adhesive according to the present invention. In  FIG. 4 , conductive particles  30 , such as metal particles, may be scattered in an adhesive film  31  formed of thermoplastic or thermosetting resin(s), thereby forming the ACF  25 . Then, although not shown, a first conductive terminal may be formed on a front surface of the ACF  25  and a second conductive terminal may be formed on a rear surface of the ACF  25 . Accordingly, pressure may be applied to the ACF  25  so that the first conductive terminal is electrically connected to the second conductive terminal by the conductive particles  30 . Next, as shown in  FIG. 3 , the ACF  25  may be positioned between the extension  16  of the touch panel  9  (in  FIG. 2 ) and the connection pads  22  of the touch controller  23  to electrically interconnect the extension  16  and the connection pads  22 . Thus, current may flow between the extension  16  and the connection pads  22 . 
       FIG. 5  is a cross sectional view of an exemplary extension and controller connection part according to the present invention. In  FIG. 5 , the extension  16  may be formed to bond to the connection pads  22  of the touch controller  23 . Since the ACF  25  may be inserted between the extension  16  of the touch panel  9  (in  FIG. 2 ) and the connection pads  22  of the touch controller  23  (in  FIG. 3 ), then the signal lines  18  of the extension  16  (in  FIG. 3 ) may be aligned to correspond to the connection pads  22 . Next, pressure and heat may be applied to the extension  16  and controller connection pads  22 , so that an adhesive  31  of the ACF  25  melts. Accordingly, the scattered conductive particles  30  of the ACF  25  may be pressed between each signal line  18  of the extension  16  and each connection pad  22 . Thus, the conductive particles  30  may be in electrical and physical contact with the signal lines  18  and the connection pads  22 , thereby ensuring sufficient electrical conduction. In addition, the adhesive  31  may be electrically charged between adjacent ones of the signal lines  18 , except at portions where the conductive particles  30  are present. Accordingly, the conductive particles  30  may be separately positioned, thereby obtaining high electrical insulating characteristics. Accordingly, adhesive reliability of the ACF  25  may be significantly affected by the performance of the conductive particles  30  and the adhesive  31 . 
     Since the ACF  25  may provide electrical interconnect between the plurality of signal lines  18  and the connection pads  22 , accurate positioning of the plurality of signal lines  18  with respect to the connection pads  22  may be necessary. For example, if the plurality of signal lines  18  are not accurately positioned with respect to the connection pads  22 , interconnection between the touch panel  9  (in  FIG. 2 ) and the touch controller  23  (in  FIG. 3 ) may not be properly made. Accordingly, the touch controller  23  (in  FIG. 3 ) may be mounted on a PCB that may include the connection pads  22 . 
     In  FIG. 3 , the connection pads  22  may be formed in the touch controller  23  to correspond to the signal lines  18  of the extension  16 . Accordingly, when the touch controller  23  is provided at a rear portion of an LCM, the touch controller  23  and the connection pads  22  may be mounted on a source or gate PCB at the rear of the LCM. In addition, a fixing guide  50  may be provided for fixing the location of the extension  16  to provide correct signal connection between each connection pad  22  and each signal line  18  of the extension  16 . The fixing guide  50  may be formed in a shape of “U” so that the connection part  17  of the extension  16  may be fixed by the fixing guide  50 . However, the fixing guide  50  may not be limited to a U-shape, and may have variable lengths and thicknesses. For example, the fixing guide  50  may be formed to have a first thickness corresponding to a total thickness of the ACF  25  and a second thickness corresponding to a thickness of the extension  16 . 
     In  FIG. 3 , the connection part  17  of the extension  16  that opposes the touch controller  23  may be formed to electrically contact the signal lines  18  using the ACF  25 . Accordingly, the connection part  17  of the extension  16  may have signal lines  18  that extend from an upper surface to a lower surface for surrounding the connection part  17  of the extension  16 . Alternatively, the signal lines  18  may be formed only along the surface that opposes a connection part of the touch controller  23 . Alternatively, the ACF  25  may be electrically connected between the signal lines  18  of the extension  16  to the connection pads  22  of the touch controller  23  using a permanent connection, such as solder. 
       FIG. 6A  is a plan view of an exemplary connection structure between an extension of a touch panel and a controller according to the present invention,  FIG. 6B  is an enlarged view of “A” of  FIG. 6A  according to the present invention, and  FIG. 6C  is a cross sectional view along I-I′ of  FIG. 6A  according to the present invention. In  FIGS. 6A ,  6 B, and  6 C, the extension  16  may include end portions  16   b  that may be divided into a plurality of finger portions  19  that may correspond to a plurality of signal lines  18 , and a main portion  16   a.  Although four end portions  16   b  are shown, any number of end portions  16   b  may be provided that correspond to the type of resistive-type touch panel to be used. Accordingly, the main portion  16   a  may include the signal lines  18  connected to electrodes  11  and  12  of the touch panel  9  along an upper or lower surface thereof. The main portion  16   a  may include insulating and flexible material(s) to provide easy connection of the signal lines  18 . For example, the extension may include epoxy or bakelite resin(s) and the end portions  16   b  may be made to be relatively thin, thereby improving flexibility of the end portions  16   b.  In addition, an end portion of the main portion  16   a  may be formed having a relatively larger width as compared to a total width of the end portions  16   b,  thereby providing a stable connection to a connection part  15  of the touch panel  9 . Moreover, the end portions  16   b  may be spaced apart from each other, thereby accommodating for soldering at the touch controller  23  (in  FIG. 2 ). 
       FIG. 7A  is a cross sectional view along II-II′ of  FIG. 6B  according to the present invention, and  FIG. 7B  is a cross sectional view along III-III′ of  FIG. 6B  according to the present invention. In  FIG. 7A , the signal lines  18  may extend along an upper surface of the main portion  16   a.  In  FIG. 7B , the signal lines  18  may extend along upper and lower surfaces of the end portion  16   b.  Accordingly, contact areas of the signal lines  18  may increase, thereby preventing electric disconnection between the touch panel  9  (in  FIG. 6A ) and the touch controller  23  (in  FIG. 2 ). 
       FIG. 8A  is a plan view of an exemplary connection structure between an extension and controller according to the present invention. In  FIG. 8A , connection pads  22  may be provided for a touch controller  23  for signal transmission on a printer circuit board  28 , wherein the connection pads  22  may be positioned to correspond to the signal lines  18  of the extension  16 . Accordingly, the connection pad  22  may be formed having rectangular plate shapes of conductive material(s). Alternatively, the connection pads may have different geometries to accommodate corresponding numbers of the signal lines  18 . For example, the connection pads  22  may be formed having opposing triangular shapes, circular shapes, and polygonal shapes. In addition, the connection pads  22  may have a hole to which the end portions  16   b  may be inserted. 
     In  FIG. 8A , the connection pads  22  may be electrically connected to the touch controller  23  using wires  24 . Alternatively, conductive lines may be provided to electrically interconnect the connection pads  22  and the touch controller  23 . In addition, the connection pads  22  may be formed to correspond to the signal lines  18 , wherein the signal lines  18  may be aligned along a lateral center line of the connection pads  22 . However, signal lines  18  corresponding to outer ones of the connection pads  22  may be offset from the lateral center line of the connection pads  22 . Alternatively, the connection pads  22  may not be provided such that the end portions  16   b  may be electrically connected to a signal connection terminal (not shown) of the touch controller  23  using solder. 
       FIG. 8B  is a cross sectional view along IV-IV′ of  FIG. 8A  according to the present invention. In  FIG. 8B , each signal line  18  may have a first signal line portion that extends along the upper surface of the end portion  16   b,  and a second signal line portion that extends along the lower surface of the end portion  16   b.  Accordingly, the second signal line portion of the signal line  18  may be electrically connected to each connection pad  22  of the touch controller  23  using solder  26  on the printed circuit board  28 . Accordingly, the electric signal connection between each connection pad  22  of the touch controller  23  and each signal line  18  of the extension  16  of the touch panel  9  may be stabilized thereby obtaining a device having a thin profile and light weight. 
       FIG. 9  is a plan view of an exemplary touch controller according to the present invention. The touch controller of  FIG. 9  may incorporate one of the exemplary connection structures of FIGS.  3  and  6 A- 6 C. In  FIG. 9 , a touch panel (not shown) may be mounted at a front of an LCM  10 , and signal connections between an extension  16  and a touch controller  23  may be provided at region “A” at a rear of the LCM  10 . Accordingly, the extension  16  from the touch panel may be connected to a connection part of the touch controller  23  integrated with the rear of the LCM  10  using an ACF  25  (in  FIGS. 3 and 5 ) or by soldering. In addition, the interconnection of the extension  16  and the touch controller  23  may be performed using a method similar to a process for bonding data driver ICs  42  onto a data driver area  40  and gate driver ICs  43  onto a gate driver area  41 . Thus, the adhesion process may be performed using a manually- or automatically-operated system. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in touch panel system of the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.