Abstract:
Provided are a touch-screen based device identification and information provision method and apparatus, and computer-readable recording mediums having recorded thereon programs for executing the touch-screen based device identification method and the information provision method. The device identification method for a touch screen device includes propagating a signal induced by touching a touch screen surface to an external device via the person, receiving information about the signal detected by the external device and an identification (ID) of the external device through a communication channel, and identifying the external device by using the received information about the detected signal and the received ID of the external device. Thus, the touch screen device and the external device can be connected to each other in real time by a simple and physical touch.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application claims the benefits of Korean Patent Application No. 10-2007-0118531, filed on Nov. 20, 2007, and Korean Patent Application No. 10-2008-0091774, filed on Sep. 18, 2008, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein in their entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a method and apparatus for identifying a device and providing device information based on a touch screen and a recording medium, and more particularly, to a method and apparatus for identifying a device and providing device information based on a touch screen and a recording medium whereby the touch screen device can identify an external device such as a cellular phone, a digital camera, a camcorder, and a personal digital assistant (PDA) according to a user&#39;s manipulation, and computer-readable recording medium having recorded thereon programs for executing the above method. 
         [0004]    2. Description of the Related Art 
         [0005]    In order to technically implement a scenario in which a touch screen device and an external device interact with each other, the external device should be easily connectable to the touch screen device, and preferably the external device has to be connected in relation to coordinates on a graphic user interface (GUI) of the touch screen device. 
         [0006]    A related art technique for a display device to identify an external device includes a radio frequency identification (RFID) scheme, a camera scheme, and a global positioning system (GPS) scheme. According to the RFID scheme, a tag reader is installed outside the display device and an RFID tag is attached to the external device in order to recognize an identification (ID) of the external device. According to the camera scheme, a camera is attached on or under a table display in order to recognize the position of the external device. According to the GPS scheme, the position of the external device is recognized using a GPS receiver. 
         [0007]    However, the position of the external device cannot be known according to the RFID scheme, a recognition rate is low and high processor performance is required due to image processing according to the camera scheme, and a position error and device complexity increase in a small space such as the display device according to the GPS scheme. 
         [0008]    Moreover, when the size of a touch screen surface is small, the external device and the touch screen device have to easily interact with each other. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides The present invention provides a touch-screen based device identification method and apparatus in order to connect a touch screen device with an external device by simple physical touching, and a computer-readable recording medium having recorded thereon a program for executing the touch-screen based device identification method. 
         [0010]    According to an aspect of the present invention, there is provided a device identification method for a touch screen device, the device identification method including: propagating a signal induced by touching a touch screen surface of the touch screen device to an external device through the person; receiving, at the touch screen device, information about the signal which is detected by the external device and an identification (ID) of the external device through a communication channel; and identifying, at the touch screen device, the external device based on the received information about the detected signal and the received ID of the external device. 
         [0011]    The signal may be a micro-current signal including a scan frequency component. 
         [0012]    The identifying the external device may include determining that the touch screen device is connected with the external device having the received ID via the person if a scan frequency component included in the information about the signal is the same as a scan frequency component of the signal induced by touching the touch screen surface. 
         [0013]    The device identification method may further include: calculating first coordinates of the touched touch screen surface; and mapping the identified external device to the calculated first coordinates of the touched touch screen surface. 
         [0014]    The device identification method may further include: when user verification information is stored in the external device, executing a user verification for allowing the external device to access the touch screen device or to access an object displayed on the first coordinates using the user verification information. 
         [0015]    The external device may be another touch screen device in addition to the touch screen device, and the device identification method may further include: calculating first coordinates of the touched touch screen surface; and mapping second coordinates of the touched touch screen surface of another touch screen surface to the first coordinates, and the mapping may be performed through the communication channel. 
         [0016]    The external device or the touch screen device may execute application services, which link the first coordinates with the second coordinates, based on the mapping result. 
         [0017]    The device identification method may further include repeating the propagating the signal to the external device and the receiving the information through the communication channel after changing a scan frequency of the signal. 
         [0018]    The device identification method may further include: receiving a confirmation request signal for identifying whether the touch screen surface of the touch screen device is touched or not from the external device through the communication channel; and transmitting a confirmation response signal which denotes that the touch screen surface of the touch screen device is touched to the external device through the communication channel. 
         [0019]    The communication channel may be a wired or wireless channel using a plug and play (PnP) protocol including a universal PnP (UPnP) protocol. 
         [0020]    The communication channel may be a wireless communication channel, and the wireless communication channel may include one or more selected from a wireless local area network (LAN), a wireless internet platform for interoperability (WIPI), Bluetooth, infrared communication, near field communication (NFC), and Zigbee, and the external device may exchange information about the wireless communication channel with the touch screen device. 
         [0021]    The external device may be one of a cellular phone, a digital camera, a camcorder, a personal digital assistant, an MP3 player, and a portable multimedia player. 
         [0022]    According to another aspect of the present invention, there is provided a device identification apparatus for a touch screen device, the device identification apparatus including: a touch sensing unit which generates a signal induced by touching a touch screen surface of the touch screen device; a reception unit which receives information about the signal propagated to the external device through the person and detected by an external device and an identification (ID) of the external device through a communication channel; and an identification unit which identifies the external device based on the received information about the signal and the received ID of the external device. 
         [0023]    According to another aspect of the present invention, there is provided a device information provision method for an external device, the device information provision method including: detecting a scan frequency component from a signal induced by touching a touch screen surface of a touch screen device and propagated to the external device through the person; generating information about the scan frequency component and identification (ID) information of the external device; and transmitting the information about the scan frequency component and the ID information from the external device to the touch screen device through a communication channel. 
         [0024]    According to another aspect of the present invention, there is provided a device information provision apparatus for an external device, the device information provision apparatus including: a detection unit which detects a scan frequency component from a signal induced by touching a touch screen surface of a touch screen device and propagated to the external device through the person; an information generation unit which generates information about the scan frequency component and identification (ID) information of the external device; and a transmission unit which transmits the information about the scan frequency component and the ID information to a touch screen device through a communication channel. 
         [0025]    According to another aspect of the present invention, there is provided a computer-readable recording medium having recorded thereon a program for executing a device identification method for a touch screen device, the device identification method including: propagating a signal induced by touching a touch screen surface of the touch screen device to an external device through the person; receiving, at the touch screen device, information about the signal which propagated to and detected by the external device and an identification (ID) of the external device through a communication channel; and identifying, at the touch screen device, the external device based on the received information about the detected signal and the received ID of the external device. 
         [0026]    According to another aspect of the present invention, there is provided a computer-readable recording medium having recorded thereon a program for executing a device information provision method for an external device, the device information provision method including: detecting, at the external device, a scan frequency component from a signal induced by touching a touch screen surface of a touch screen device and propagated to the external device through the person; generating, at the external device, information about the scan frequency component and identification (ID) information of the external device that has received the signal; and transmitting the information about the scan frequency component and the ID information from the external device to the touch screen device through a communication channel. 
         [0027]    According to embodiments of the present invention, the external device detects the scan frequency component induced on the touch screen surface by touching the touch screen surface via the person, and thus, the touch screen device and the external device can be connected to each other in real time by a simple physical touch. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0029]      FIG. 1  illustrates a touch-screen based device identification system according to a first exemplary embodiment of the present invention; 
           [0030]      FIG. 2  illustrates a touch-screen based device identification system according to a second exemplary embodiment of the present invention; 
           [0031]      FIG. 3  illustrates a touch-screen based device identification system according to a third exemplary embodiment of the present invention; 
           [0032]      FIG. 4  is a block diagram of a touch-screen based device identification system according to an exemplary embodiment of the present invention; 
           [0033]      FIG. 5  is a flowchart illustrating a touch-screen based device identification method for a touch screen device according to an exemplary embodiment of the present invention; 
           [0034]      FIG. 6  is a flowchart illustrating a device information provision method for an external device according to another exemplary embodiment of the present invention; and 
           [0035]      FIG. 7  illustrates a touch-screen based device identification system according to a fourth exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that like reference numerals refer to like elements illustrated in one or more of the drawings. In the following description of the present invention, detailed descriptions of known functions and configurations incorporated herein will be omitted for conciseness and clarity. 
         [0037]      FIG. 1  illustrates a touch-screen based device identification system according to a first exemplary embodiment of the present invention. 
         [0038]    Referring to  FIG. 1 , the touch-screen based device identification system includes an external device  110  and a touch screen device  120 . The external device  110  and the touch screen device  120  are connected with each other through a communication channel  130 . It is assumed that a person  140  touches a touch screen surface of the touch screen device  120  with one hand while holding the external device  110  with the other hand. In another exemplary embodiment of the present invention, a person  140  may touch a touch screen surface of the touch screen device  120  by means of using a conductive medium such as metal. 
         [0039]    The external device  110  is a consumer electronics (CE) device capable of communicating with another device through the communication channel  130 . The external device  110  may be a cellular phone, a digital camera, a camcorder, a personal digital assistant (PDA), an MP3 player, or a portable multimedia player (PMP). In another exemplary embodiment of the present invention, the external device  110  may be another touch screen device in addition to the touch screen device  120 . 
         [0040]    A signal induced by touching a touch screen surface of the touch screen device  120  propagates to the external device  110  via the person  140 . A detection unit  150  of the external device  110  detects a scan frequency component from the signal induced by a touch of the touch screen surface in the touch screen device  120 . 
         [0041]    Upon detection of the scan frequency component, the external device  110  generates information about the detected scan frequency component and ID information of the external device  110  and transmits the generated information and ID information to the touch screen device  120  through the communication channel  130 . The external device  110  may include a band pass filter for detecting a micro-current signal that is induced from the touch screen surface and is received via the person  140 . The micro-current signal propagating to the external device  110  is detected after passing through the band pass filter of the external device  110 . 
         [0042]    The touch screen device  120  is a device capable of performing specific processing by recognizing the position of a character or a particular position on the touch screen surface, which is touched by a human hand, without using a keyboard. A touch-screen scheme may be classified into types including a resistive film type and a static capacitance type. According to the static capacitance type, the touch screen surface is electrically charged, sensors are installed along the circumference of the touch screen surface, and a touched position is recognized by sensing the amount of electric charges lost by a touch. 
         [0043]    Herein, the touch screen device  120  may be adapted by the static capacitance type. According to the static capacitance type, the touch screen device  120  performs a periodic scan in order to sense a touch. However, the touch screen device  120  is not limited to the static capacitance type, and may include all kinds of devices, in which micro-current signals including a certain frequency (for example, scan frequency) are induced when the touch screen surface is touched. 
         [0044]    According to the static capacitance type, the touch screen device  120  performs scanning operation regularly to sense the touch. Thus, when the person  140  touches the touch screen surface of the touch screen device  120  with one hand while holding the external device  110  with the other hand, a micro-current including a particular frequency, e.g., a scan frequency, is induced by touching the touch screen surface. A micro-current signal including a scan frequency component, induced by touching the touch screen surface propagates to the external device  110  via the person  140 . 
         [0045]    The touch screen device  120  also receives information about the scan frequency component detected by the detection unit  150  and an ID of the external device  110  from the external device  110  through the communication channel  130 . The touch screen device  120  recognizes that it is connected with the external device  110  via the person  140  by using the information about the detected scan frequency component and the ID of the external device  110 , which are received from the external device  110 . 
         [0046]    In addition, in order to distinguish the touch screen device  120  that propagates the induced signal from a plurality of touch screen devices, the external device  110  may broadcast confirmation request signals, which identify whether the touch screen surface of the touch screen device  120  is touched or not, to a plurality of touch screen devices through communication channels. Then, the touch screen device  120 , which propagates the signal induced by touching the touch screen surface to the external device  110 , may transmit a confirmation response signal that notifies the touch to the touch screen surface to the external device  110  through the communication channel  130 . The other touch screen devices, touch screen surfaces of which are not touched, may not transmit the confirmation response signal to the external device  110 . 
         [0047]    The communication channel  130  is a data transmission/reception path that is previously established before the person  140  touches the external device  110  and the touch screen device  120 . Thus, the external device  110  and the touch screen device  120  are in a state where they can exchange data through the communication channel  130  whenever needed. 
         [0048]    The communication channel  130  is a local connection using a plug-and-play (PnP) protocol such as a universal PnP (UPnP) protocol and may be a wired or wireless channel. In addition, the communication channel  130  may be wireless communication channel, and the wireless communication channel may include one or more of a wireless local area network (LAN), a wireless internet platform for interoperability (WIPI), Bluetooth, infrared communication, near field communication (NFC), and Zigbee. 
         [0049]    In addition, the external device  110  exchanges information about the communication channel (for example, wireless communication channel) with the touch screen device  120 , and may communicate through the selected communication channel based on the exchanged information. For example, when the external device  110  or the touch screen device  120  includes a plurality of communication channels, the external device  110  notifies the touch screen device  120  of the communication channels included in the external device  110 , and the touch screen device  120  may select the appropriate communication channel by comparing the communication channels of the external device  110  with the communication channels of the touch screen device  120 . 
         [0050]    The person  140  can cause the external device  110  and the touch screen  120  to interact with each other by touching the touch screen surface of the touch screen device  120  with one hand while holding the external device  110  with the other hand. Since a human body is composed mostly of water including salt, the human body generally has the characteristics of a conductor at tens of KHz. Thus, a micro-current signal may propagate between the external device  110  and the touch screen  120  via the body of the person  140  who touches the external device  110  and the touch screen  120 . In this state, the touch screen device  120  acts as if a position touched by the hand of the person  140  is touched by the external device  110  and can perform particular processing. That is, the touch screen device  120  calculates the first coordinates of the touched point on the touch screen surface, and then, maps the external device  110  to the first coordinates. Here, mapping allows various applications to be executed as if the external device  110  touches the first coordinates. 
         [0051]    In addition, when the external device  110  stores personal information or verification information (hereinafter, referred to as ‘user verification information’), services that allow the external device to access the touch screen device  120  or allow the external device to access the object displayed on the first coordinates of the touch screen device  120  can be provided using the user verification information. 
         [0052]    In addition, as described above, the external device  110  may be another touch screen device in addition to the touch screen device  120 . 
         [0053]      FIG. 7  illustrates that the external device  110  is another touch screen device. Referring to  FIG. 7 , processes for a touch screen device A  710  to identify a touch screen device B  730  via person  760  (or opposite processes) are similar to those of the embodiment shown in  FIG. 1 . however, the touch screen devices A and B  710  and  730  may include detection units for detecting signals that are induced on touch screen surfaces of the counterpart touch screen devices  710  or  730  and are propagated. The detection units may be installed in the touch screen surface or on a position separated from the touch screen surface. The detection of the induced signals is described already with reference to  FIG. 1 , and thus, detailed descriptions thereof are omitted. 
         [0054]    The touch screen device A  710  calculates first coordinates X  720  that represent touched location on the touch screen surface of the touch screen device A  710 , and the touch screen device B  730  calculates second coordinates Y  740  that represent touched location on the touch screen surface of the touch screen device B  730 . After that, the touch screen devices A and B  710  and  730  may perform the mapping operation of the first and second coordinates X  720  and Y  740  through a communication channel  750 . Then, the touch screen devices A  710  and B  730  may execute an application service that links the first coordinates X  720  with the second coordinates Y  740  based on a result of the mapping operation. Through the above linkage between the coordinates, application services according to states of the touch screen devices and intention of the user can be provided. 
         [0055]    For example, the touch screen device A  710  may transmit a control signal for allowing the object displayed on the first coordinates X  720  of the touch screen device A  710  (for example, icons, characters, products, or colors) to be displayed on the second coordinates Y  740  of the touch screen device  730  to the touch screen device B  730 , or receives the control signal from the touch screen device B  730 . For example, the color represented on the first coordinates X  720  may be equally displayed on the second coordinates Y  740 , and the product displayed on the first coordinates X  720  may be moved to the second coordinates Y  740 . On the other hand, the color represented on the second coordinates Y  740  may be equally displayed on the first coordinates X  720 , and the product displayed on the second coordinates Y  740  may be moved to the first coordinates X  720 . 
         [0056]    Otherwise, a user interface such as a pop-up menu may be displayed in the touch screen devices, and thus, the user of the touch screen device A  710  or the touch screen device B  730  may select one of a plurality of services, coordinates of which can be linked with each other. 
         [0057]      FIG. 2  illustrates a touch-screen based device identification system according to a second exemplary embodiment of the present invention. 
         [0058]    An external device  210 , a communication channel  230 , a person  240 , and a reception unit  250 , which are illustrated in  FIG. 2 , operate in the same manner respectively as the external device  110 , the communication channel  130 , the person  140 , and the detection unit  150 , which are illustrated in  FIG. 1 , and thus will not be described again. 
         [0059]    While the touch screen device  120  illustrated in  FIG. 1  operates by touching the touch screen surface, a touch screen device  220  illustrated in  FIG. 2  operates by touching one of touch spots  260  installed along the circumference of the touch screen device  220 . In other words, the touch screen  220  illustrated in  FIG. 2  operates by a touch to the touch spot  260  instead of to the touch screen surface. 
         [0060]    The person  240  indicates a particular position on the touch screen surface by touching the touch spot  260  in order to cause the touch screen device  220  to perform particular processing. The touch spot  260  is designed so that a micro-current having a scan frequency component can flow through the touch spot  260 . Thus, once the person  240  touches the touch spot  260 , a micro-current signal propagates to the external device  210  via the person  240 . The touch screen device  220  receives information about the scan frequency component and an ID of the external device  210  from the external device  210 . 
         [0061]    Consequently, if the person  240  touches the touch spot  260  of the touch screen device  220  with one hand, the touch screen device  220  can recognize that it is connected with the external device  210  the person  240  holds with the other hand. 
         [0062]      FIG. 3  illustrates a touch-screen based device identification system according to a third exemplary embodiment of the present invention, in which there exists a plurality of external devices  310  and  330  or a plurality of touch screen devices  315  and  335 . 
         [0063]    For example, it is assumed that a person A  320  holds an external device A  310  with one hand and touches a touch screen device A  315  with the other hand. It is also assumed that a person B  340  holds an external device B  330  with one hand and touches a touch screen device B  335  with the other hand. If the person A  320  and the person B  340  touch the touch screen device A  315  and the touch screen device B  335 , respectively, at almost the same time, the external devices A  310  and B  330  transmit information about scan frequency components and an ID of the external devices  310  and  320  to the touch screen device  315  and the touch screen device B  335  through communication channels  350  and  360  and communication channels  355  and  365 , respectively. However, if scan frequencies of micro-current signals induced in the touch screen devices A  315  and B  335  are the same as each other, the touch screen device A  315  or B  335  cannot recognize which one of the external devices A  310  and B  330  it is connected with. 
         [0064]    In this case, the touch screen device A  315  or B  335  may be designed in such a way as to change a scan frequency of a micro-current signal induced by touching a touch screen surface. For example, when the touch screen device A  315  or B  335  receives scan frequency information and an ID from the plurality of external devices  310  and  330  within a predetermined period of time, the touch screen device A  315  or B  335  temporarily changes a scan frequency. The touch screen device A  315  or B  335  then receives scan frequency information corresponding to the changed scan frequency and an ID from the external devices  310  and  330  again. However, if both the touch screen device A  315  and the touch screen device B  335  change scan frequencies to another same frequency, the problem described above may occur again. This problem may be solved by using a method of randomly determining a point of time for changing the scan frequency of the touch screen device A  315  or B  335  within a predetermined time range. However, in order to prevent the scan frequencies of the touch screen device A  315  and the touch screen device B  335  from being simultaneously changed to another same scan frequency, various methods may be used without being limited to the method described above. 
         [0065]    Subsequently, the touch screen device A  315  or B  335  can identify the external device  310  or  330  connected with the touch screen device A  315  or B  335  by temporarily changing the scan frequency of the touch screen device A  315  or B  335 . 
         [0066]      FIG. 4  is a block diagram of a touch-screen based device identification system according to an exemplary embodiment of the present invention. 
         [0067]    Referring to  FIG. 4 , the touch-screen based device identification system includes an external device  410  and a touch screen device  450 . The external device  410  and the touch screen device  450  are connected with each other through a communication channel  445 . A person  480  touches a detection unit  420  of the external device  410  with one hand and touches a touch sensing unit  455 , i.e., a touch screen surface, of the touch screen device  450  with the other hand. 
         [0068]    The touch screen device  450  may include the touch sensing unit  455 , a reception unit  460 , and an identification unit  465 . The touch screen device  450  may further include a mapping unit  470  and a coordinates calculation unit  475 . 
         [0069]    The touch sensing unit  455  generates a signal induced by touching the touch screen surface. The induced signal is a micro-current signal including a scan frequency component and propagates to the detection unit  420  of the external device  410  via the person  480 . 
         [0070]    The touch sensing unit  455  can temporarily change a scan frequency of the micro-current signal induced by touching the touch screen surface. An objective that can be achieved by changing the scan frequency has already been described and thus will not be further described here. 
         [0071]    The reception unit  460  receives information about the scan frequency component detected by the external device  410  and an ID of the external device  410  through the communication channel  445 . 
         [0072]    The identification unit  465  identifies the external device  410  by using the information about the scan frequency component and the ID of the external device  410 , which are received by the reception unit  460 . For example, the identification unit  465  determines a scan frequency based on the information about the scan frequency component and compares the determined scan frequency with a scan frequency of the micro-current signal induced by a touch. If the determined scan frequency is the same as the scan frequency of the induced micro-current signal, the identification unit  465  determines that the touch screen device  450  is connected with the external device  410  having the received ID. Information about the scan frequency of the micro-current signal induced by a touch of the person  480  may be received from the touch sensing unit  455  or may be stored in the identification unit  465 . 
         [0073]    The coordinates calculation unit  475  calculates coordinates of the touch screen surface touched (that is, first coordinates). 
         [0074]    The mapping unit  470  maps the coordinates of the touch screen surface touched to the identified external device  410 . By doing so, the touch screen device  450  can act as if a position touched by a hand of the person  480  is touched using the external device  41  and can perform particular processing. 
         [0075]    The external device  410  includes a detection unit  420 , an information generation unit  435 , and a transmission unit  440 . The external device  410  may be, for example, a cellular phone, a digital camera, a camcorder, a PDA, an MP3 player, or a PMP. 
         [0076]    The detection unit  420  detects a scan frequency component from a micro-current signal propagating from the touch sensing unit  455  and transmits the detected scan frequency component to the information generation unit  435 . For example, the detection unit  420  may include a band pass filter  425  and a tone decoder  430 . The band pass filter  425  performs band pass filtering on the micro-current signal by using a scan frequency as a center frequency. The tone decoder  430  performs tone-decoding on the band-pass filtered signal output from the band pass filter  425 . As a result, the detection unit  420  outputs information indicating whether the scan frequency component is included in the micro-current signal. 
         [0077]    The information generation unit  435  generates information about the scan frequency component and ID information of the external device  435  that has received the micro-current signal. The information generation unit  435  previously stores the ID information of the external device  410 . 
         [0078]    The transmission unit  440  transmits the information about the scan frequency component and the ID information of the external device  410  to the reception unit  460  of the touch screen device  450  through the communication channel  445 . 
         [0079]    In addition, the external device  410  may be another touch screen device in addition to the touch screen device  450 . In this case, the mapping unit  470  may map the second coordinates of the external device  410  to the first coordinates of the touch screen device  450 . The mapping unit  470  may perform the mapping operation through the communication channel  445 . 
         [0080]    In addition, the mapping unit  470  may control a control signal, which allows the object displayed on the first coordinates to be displayed on the second coordinates, transmitted to the external device  410  or received from the external device  410 . Consequently, the external device  410  or the touch screen device  450  may execute various application services caused by the linkage between the first and second coordinates based on the mapping result. 
         [0081]    The communication channel  445  may be a wired or wireless channel using a PnP protocol such as an UPnP protocol. 
         [0082]      FIG. 5  is a flowchart illustrating a touch-screen based device identification method for a touch screen device according to an exemplary embodiment of the present invention. 
         [0083]    Referring to  FIG. 5 , in operation  510 , the touch screen device propagates a micro-current signal, including a scan frequency component, induced by touching a touch screen surface to an external device via a person. The external device may be, for example, a cellular phone, a digital camera, a camcorder, a PDA, an MP3 player, or a PMP. The touch screen device may temporarily change a scan frequency of a micro-current induced by touching the touch screen surface. 
         [0084]    In operation  520 , receives information about the scan frequency component detected by the external device and an ID of the external device from the external device through a communication channel. The communication channel may be a wired or wireless channel using a PnP protocol such as an UPnP protocol. 
         [0085]    In operation  530 , the touch screen device identifies the external device by using the received information about the scan frequency component and the received ID of the external device. For example, the touch screen device may determine that it is connected with the external device having the received ID if the received information about the scan frequency component is the same as a scan frequency component of the signal induced by a touch. 
         [0086]    In operation  540 , the touch screen device calculates coordinates of the touched touch screen surface. 
         [0087]    In operation  550 , the touch screen device maps the external device identified in operation  530  to the calculated coordinates of the touched touch screen surface. 
         [0088]    In addition, the touch screen device may calculate first coordinates of the touched point on the touch screen surface, and then, maps the external device to the first coordinates. 
         [0089]    In addition, the touch screen device may execute user verification services that allow the external device to access the touch screen device or to access the object displayed on the first coordinates of the touch screen device using the user verification information stored in the external device. 
         [0090]    Also, as described above, the external device may be another touch screen device in addition to the touch screen device. In this case, the touch screen device calculates first coordinates of the touched point on the touch screen surface, and then, performs a mapping operation of the calculated first coordinates to second coordinates that represent the touched point on the touch screen surface of another touch screen device through the communication channel. 
         [0091]    In addition, the touch screen device may transmit a control signal, which allows the object represented on the first coordinates to be represented on the second coordinates, to the other touch screen device or may receive the control signal from the other touch screen device. 
         [0092]      FIG. 6  is a flowchart illustrating a device information provision method for an external device according to another exemplary embodiment of the present invention. 
         [0093]    Referring to  FIG. 6 , in operation  610 , the external device detects a scan frequency component from a micro-current signal including a scan frequency component induced by touching a touch screen surface. For example, the external device may perform band-pass filtering on the micro-current signal by using a san frequency as a center frequency and perform tone-decoding on the band-pass filtered signal. The external device may be, for example, a cellular phone, a digital camera, a camcorder, a PDA, an MP3 player, or a PMP. 
         [0094]    In operation  620 , the external device generates information about the scan frequency component and ID information of the external device that has received the micro-current signal. 
         [0095]    In operation  630 , the external device transmits the information about the scan frequency component and the ID information to the touch screen device through a communication channel. The communication channel may be a wired or wireless channel using a PnP protocol such as an UPnP protocol. 
         [0096]    When the scan frequency of a micro-current induced by touching the touch screen surface is temporarily changed by the touch screen device, the external device may repetitively perform operations  610  through  630 . 
         [0097]    In addition, when the external device is identified by the touch screen device and is mapped on the first coordinates that represent the touched point on the touch screen surface in the touch screen device, the external device may access the touch screen device using the user verification information stored therein or may execute the user verification process for accessing the object displayed on the first coordinates of the touch screen device. 
         [0098]    In addition, the external device may be another touch screen device in addition to the touch screen device. In this case, the external device calculates second coordinates that represent the touched point of the touch screen surface of the external device, and may perform a mapping operation of the second coordinates to the first coordinates of the touch screen device. 
         [0099]    In addition, for example, the external device may transmit a control signal, which allows the object displayed on the first coordinates to be displayed on the second coordinates, to the touch screen device or may receive the control signal from the touch screen device. 
         [0100]    A program for executing a touch-screen based device identification method according to the present invention can be embodied as a computer-readable code on a computer-readable recording medium. The computer-readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of computer-readable recording media include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves. The computer-readable recording medium can also be distributed over network of coupled computer systems so that the computer-readable code is stored and executed in a decentralized fashion. 
         [0101]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.