TECHNICAL FIELD 
     The present invention relates to a mobile terminal provided with a security function, and more particularly, to a mobile terminal provided with a security function to prevent access to data in a security region where important data is saved when a casing of the mobile terminal is forcibly opened. 
     BACKGROUND 
     In general, mobile terminals are a concept including mobile communication terminals, payment terminals, and various computers and tablet PCs for inputting and processing data. 
     In the following description, for convenience of explanation, a payment terminal is mainly discussed. 
     The payment terminal includes a central processing unit for processing input data and various types of memories for storing data. 
     Important information that is necessary to protect from being leaked to the outside may be processed by or stored in the central processing unit and the memory. 
     In the payment terminal, it is very important to prevent leakage of important data related to security stored in relation with card payments, personal authentication, personal information, and company secrets. 
     In other words, when a user who is not security-approved accesses a mobile terminal where important data is stored by opening a casing in order to leak the data to the outside, a serious security breach may occur. 
     To address the above problem, in the payment terminal according to a related art, when the casing of the payment terminal storing important data is opened, an anti-tampering protection member which may deny access to the important data is provided. 
     However, in the mobile terminal according to a related art, accessing to the important data may be denied only when the casing is opened. It is a demerit that, when opening the casing is tried, such a try may not be detected. 
     SUMMARY 
     The present invention provides a mobile terminal provided with a security function which may prevent leakage of important data by denying access to data in a security region when there is a possibility of leakage of the important data to the outside, for example, not only when both of an upper casing and a lower casing are opened, but also when opening of a casing is tried. 
     According to an aspect of the present inventive concept, there is provided a mobile terminal provided with a security function which includes a casing comprising a data input portion for inputting data and an upper casing and a lower casing which are capable of being assembled or disassembled with respect to each other, a circuit board for processing input data and comprising a security unit that is electrically connected to the data input portion and requiring security, an anti-tampering conduction portion arranged between the casing and the circuit board and electrically connected to the circuit board by being pressed when the upper casing and the lower casing are assembled to each other, and a control portion denying access to data of the security unit based on a resistance value of the anti-tampering conduction portion. 
     The anti-tampering conduction portion may be pressed by a coupling member that penetrates through the upper casing and the lower casing. 
     When a resistance value between the anti-tampering conduction portion and the circuit board is out of a preset range, the control portion may deny access to the data of the security unit. 
     When the resistance value between the anti-tampering conduction portion and the circuit board is infinite and the electric connection between the anti-tampering conduction portion and the circuit board is disconnected, the control portion may deny access to the data of the security unit. 
     The circuit board may include a lower circuit board arranged above the lower casing and an upper circuit board arranged above the lower circuit board and the anti-tampering conduction portion may be arranged between the upper circuit board and the lower circuit board and connected to at least one of the upper circuit board and the lower circuit board. 
     The mobile terminal provided with a security function may further include a security partition that is arranged between the upper circuit board and the lower circuit board to deny access to the data of the security unit from a side portion of the casing and connected to each of the upper circuit board and the lower circuit board, in which the anti-tampering conduction portion is electrically connected to the security partition. 
     An accommodation opening for accommodating the anti-tampering conduction portion may be formed in the security partition. 
     The anti-tampering conduction portion may be connected to each of the upper circuit board and the lower circuit board, the security partition may include a lower security partition connected to the lower circuit board and an upper security partition arranged above the lower security partition and connected to the upper circuit board, and the anti-tampering conduction portion may be electrically connected to at least one of the upper security partition and the lower security partition. 
     The security partition may include a lower security partition connected to the lower circuit board and an upper security partition arranged above the lower security partition and connected to the upper circuit board The anti-tampering conduction portion may include a plurality of anti-tampering prevention members separated from one another, and each of the plurality of anti-tampering prevention members are electrically connected to at least two of the upper circuit board, the lower circuit board, the upper security partition, and the lower security partition. 
     The anti-tampering prevention member may be conductive rubber exhibiting conductivity and elasticity. 
     The security unit may be a central processing unit processing data or a storage medium storing data. 
     The denying of the data of the security unit may be erasing predetermined data. 
     In order to protect the security unit, the security partition may be provided in a closed type of encompassing an entire perimeter of the security unit or in an open type of encompassing a perimeter of the security unit with a part of the security partition opened. 
     In order to protect a connection socket, the security partition may be provided in a closed type of encompassing an entire perimeter of the connection socket or in an open type of encompassing a perimeter of the connection socket with a part of the connection socket opened. 
     According to the exemplary embodiments, leakage of important data may be prevented by denying access to data in a security region when there is a possibility of leakage of the important data to the outside, for example, not only when both of an upper casing and a lower casing are opened, but also when opening of a casing is tried. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a mobile terminal provided with a security function according to an exemplary embodiment. 
         FIG. 2  is a coupled perspective view of a circuit board in a mobile terminal provided with a security function according to an exemplary embodiment. 
         FIG. 3  illustrates connection of an anti-tampering conduction portion in a mobile terminal provided with a security function according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The attached drawings for illustrating preferred embodiments of the present inventive concept are referred to in order to gain a sufficient understanding of the present inventive concept, the merits thereof, and the objectives accomplished by the implementation of the present inventive concept. 
     Hereinafter, the present inventive concept will be described in detail by explaining preferred embodiments of the inventive concept with reference to the attached drawings. Like reference numerals in the drawings denote like elements. 
     Among the terms used in the present specification, the term “tamper” signifies opening a casing by an external force. 
       FIG. 1  is an exploded perspective view of a mobile terminal provided with a security function according to an exemplary embodiment.  FIG. 2  is a coupled perspective view of a circuit board in a mobile terminal provided with a security function according to an exemplary embodiment.  FIG. 3  illustrates connection of an anti-tampering conduction portion in a mobile terminal provided with a security function according to an exemplary embodiment. 
     As illustrated in the drawings, the mobile terminal provided with a security function according to the present exemplary embodiment includes a casing  200 , a circuit board  300 , an anti-tampering conduction portion  400 , and a control portion  500 . 
     Referring to  FIGS. 1 and 2 , the casing  200  includes a data input portion  230  provided at one side for inputting a predetermined data. The casing  200  includes an upper casing  210  and a lower casing  220  so as to be assembled or disassembled with respect to each other. 
     The data input portion  230  has a physical input key so as to be electrically connected to the circuit board  300  or may be provided as a touch screen type. 
     The upper casing  210  and the lower casing  220  may be connected to each other by means of a coupling member  240  such as a screw or a bolt. 
     An opening into which a screw or bolt may be inserted is formed in the lower casing  220 . A coupling portion to which the screw or bolt may be coupled is formed in the upper casing  210 . The coupling member  240  such as a screw or bolt inserted into the opening of the lower casing  220  may be coupled to the coupling portion of the upper casing  210  by penetrating through the lower casing  220  and the upper casing  210 . 
     Alternatively, the coupling portion may be formed in the lower casing  220  and the opening into which a screw or bolt is inserted may be formed in the upper casing  210 . 
     Referring to  FIGS. 1 and 2 , the circuit board  300  is arranged inside the casing  200  and electrically connected to the data input portion  230  to process a signal input through the data input portion  230  and output a result corresponding to the input signal through an output portion. 
     Also, the circuit board  300  may include a security unit  600  that includes a central processing unit for processing input data and a storage medium such as a memory for storing data. 
     The central processing unit of the security unit  600  may process data that requires prevention of leakage to the outside. The data requiring prevention of leakage to the outside may be stored in the storage medium of the security unit  600 . 
     Alternatively, the circuit board  300  may include a lower circuit board  320  and an upper circuit board  310 . The lower circuit board  320  is arranged above the lower casing  220 . The upper circuit board  310  is arranged under the upper casing  210  and above the lower circuit board  320 . 
     When the circuit board  300  includes the upper circuit board  310  and the lower circuit board  320 , an input key may be connected to the upper circuit board  310  and the lower circuit board  320  may include the central processing unit, various storage media, or a communication unit. 
     The anti-tampering conduction portion  400  which is described later may be arranged between the upper circuit board  310  and the lower circuit board  320  and connected to at least one of the upper circuit board  310  and the lower circuit board  320 . 
     In other words, the anti-tampering conduction portion  400  may be connected to one of the upper circuit board  310  and the lower circuit board  320  to be pressed by the casing  200 , or connected to both of the upper circuit board  310  and the lower circuit board  320  to be pressed by the casing  200 . 
     Referring to  FIG. 1 , in the present exemplary embodiment, the anti-tampering conduction portion  400  is arranged between the upper circuit board  310  and the lower circuit board  320  to be pressed. 
     In other words, when the upper casing  210  and the lower casing  220  forming the casing  200  are assembled, the anti-tampering conduction portion  400  is pressed by the coupling member  240  penetrating through the upper casing  210  and the lower casing  220 , to be electrically connected to the circuit board  300 . 
     In other words, after the anti-tampering conduction portion  400  is arranged between the casing  200  and the circuit board  300 , the upper casing  210  and the lower casing  220  are coupled to each other by using a screw or bolt that penetrates through the upper casing  210  and the lower casing  220 . 
     When the upper casing  210  and the lower casing  220  are coupled by using the coupling member  240  such as a screw or bolt, the upper circuit board  310  and the lower circuit board  320  press the anti-tampering conduction portion  400  and the anti-tampering conduction portion  400  may thereby be electrically connected to the circuit board  300 . 
     An anti-tampering prevention member  410  may be formed of conductive rubber exhibiting conductivity and elasticity and in which a resistance value between the anti-tampering prevention member  410  and the circuit board  300  to which the anti-tampering prevention member  410  is electrically connected varies according to a change in a degree of compression. 
     Alternatively, when a degree of pressing of the upper casing  210  and the lower casing  220  decreases, a degree of pressing between the anti-tampering conduction portion  400  and the circuit board  300  changes and thus the resistance value between the anti-tampering conduction portion  400  and the circuit board  300  changes. 
     In other words, when the screw or bolt coupled to the upper casing  210  and the lower casing  220  is rotated to release the coupling, a change occurs in the degree of pressing by the casing  200  against the anti-tampering conduction portion  400 . The resistance value between the anti-tampering conduction portion  400  and the circuit board  300  is changed according to the change in the amount of compression of the anti-tampering conduction portion  400 . 
     When the resistance value of the anti-tampering conduction portion  400  is changed by an external force, the control portion  500  denies access to data of the security unit  600 , for example, by erasing preset data. 
     In detail, the control portion  500  presets the resistance value between the anti-tampering conduction portion  400  and the circuit board  300 . When the resistance value goes out of a preset range due to application of an external force, the control portion  500  may determine that there is an external access to the data of the security unit  600  and may deny the access to the data of the security unit  600 , for example, by erasing the data. 
     In other words, when an external force is applied to open the casing  200 , the resistance value between the anti-tampering conduction portion  400  and the circuit board  300  is changed. In this case, the control portion  500  may transmit a signal to the security unit  600  to deny the access to the data of the security unit  600 . 
     Alternatively, when the casing  200  is opened by the external force, in other words, the electric connection between the anti-tampering conduction portion  400  and the circuit board  300  is disconnected, the resistance value between the anti-tampering conduction portion  400  and the circuit board  300  becomes infinity. In this case, the control portion  500  may determine that there is an external access to the data of the security unit  600  and deny the access to the data of the security unit  600 , for example, by erasing the data. 
     The security unit  600  may include a central processing unit (CPU) for processing data or a storage medium including various memories for storing data. 
     In other words, when the casing  200  is to be opened by an external force or is opened, an access to the data being operated by the central processing unit or the data stored in the storage medium in the casing  200  is denied. 
     The denying of accessing to the data of the security unit  600  may be erasing of predetermined data. 
     In other words, although all pieces of data may be erased, materials related to security or data that may be prevented from being leaked to the outside may be previously determined and set and then, when an external access as described above is detected, only the predetermined data is erased. 
     Alternatively, the control portion  500  may be arranged on the circuit board  300  or the control portion  500  may be separated arranged to be connected to the circuit board  300 . 
     Referring to  FIG. 1 , a mobile terminal  100  provided with a security function according to an exemplary embodiment may further include a security partition  700 . 
     The security partition  700  is arranged between the upper circuit board  310  and the lower circuit board  320  to be connected to the upper circuit board  310  and the lower circuit board  320 , and may be electrically connected to the anti-tampering conduction portion  400 . 
     The mobile terminal  100  provided with a security function may deny the access to the data of the security unit  600  for a case of accessing to the data of the security unit  600  not only through the upper or lower side of the casing  200 , but also through a side portion of the casing  200 . 
     In other words, when the anti-tampering conduction portion  400  is electrically connected to the security partition  700 , and an external force acts through the side portion so that the resistance value between the anti-tampering conduction portion  400  and the security partition  700  is changed as described above, the access to the data of the security unit  600  may be denied. 
     Referring to  FIG. 1 , an accommodation opening  730  may be formed in the security partition  700 . The anti-tampering conduction portion  400  may be stably supported after being accommodated in the accommodation opening  730  formed in the security partition  700 . 
     When multiple anti-tampering conduction portions  400  are provided, a corresponding number of accommodation openings  730  may be provided. 
     Alternatively, referring to  FIGS. 1 and 2 , the security partition  700  may include an upper security partition  710  and a lower security partition  720 . 
     The lower security partition  720  is connected to an upper portion of the lower circuit board  320 . The upper security partition  710  is arranged above the lower security partition  720  to be connected to the upper circuit board  310 . 
     While connected to each of the upper circuit board  310  and the lower circuit board  320 , the anti-tampering conduction portion  400  may be electrically connected to at least one of the upper security partition  710  and the lower security partition  720 . 
     In other words, one end of the anti-tampering conduction portion  400  is connected to the upper circuit board  310  and the other end thereof is connected to the lower circuit board  320 . Thus, the anti-tampering conduction portion  400  is connected to both of the upper circuit board  310  and the lower circuit board  320 . 
     Although the anti-tampering conduction portion  400  penetrates through both of the upper security partition  710  and the lower security partition  720  to be electrically connected to the upper circuit board  310  and the lower circuit board  320 , the anti-tampering conduction portion  400  is not necessarily electrically connected to both of the upper security partition  710  and the lower security partition  720  and may be electrically connected to any one of the upper security partition  710  and the lower security partition  720  as necessary. 
     As such, according to the mobile terminal  100  provided with a security function according to the present exemplary embodiment, the anti-tampering conduction portion  400 , the upper security partition  710 , and the lower security partition  720  are connected to one another in various methods. Access to the data of the security unit  600  from various directions, that is, the access to the data of the security unit  600  through the upper, lower, or side portion, may be accurately detected. 
     Also, referring to  FIG. 3 , when the security partition  700  includes the lower security partition  720  and the upper security partition  710 , the anti-tampering conduction portion  400  may include a plurality of the anti-tampering prevention members  410 . The anti-tampering prevention members  410  may be separated from one another. 
     In other words, in order to more clearly detect the access to the data of the security unit  600  tried through various parts of the casing  200 , the anti-tampering conduction portion  400  is provided in a multiple number and arranged at various positions between the upper circuit board  310  and the lower circuit board  320 . 
     Each of the anti-tampering prevention members  410  may be electrically connected to at least two of the upper circuit board  310 , the lower circuit board  320 , the upper security partition  710 , and the lower security partition  720 . 
     In other words, referring to  FIG. 3 , a first anti-tampering prevention member  410   a  is connected to the lower security partition  720  by penetrating through the upper circuit board  310  and the upper security partition  710 . 
     In this case, the first anti-tampering prevention member  410   a  may be electrically connected to all of the upper circuit board  310 , the upper security partition  710 , and the lower security partition  720 , or the first anti-tampering prevention member  410   a  may be electrically connected to only the upper circuit board  310  and the lower security partition  720 , not to the upper security partition  710 . 
     A second anti-tampering prevention member  410   b  may be connected from the upper circuit board  310  to the lower circuit board  320  by penetrating through the upper security partition  710  and the lower security partition  720 . 
     In this case, the second anti-tampering prevention member  410   b  may be electrically connected to all of the upper circuit board  310 , the upper security partition  710 , the lower security partition  720 , and the lower circuit board  320 , to only the upper circuit board  310  and the lower circuit board  320 , or to only the upper circuit board  310  and the lower circuit board  320  and to at least one of the upper security partition  710  and the lower security partition  720 . 
     Also, as described above, the anti-tampering prevention members  410   a ,  410   b ,  410   c ,  410   d , and  410   e  may be electrically connected in a variety of combinations as necessary, and the access to the data of the security unit  600  through various parts may be denied. 
     In other words, by electrically combining the anti-tampering prevention member  410   a ,  410   b ,  410   c ,  410   d , and  410   e  in various methods, important data may be prevented from being leaked to the outside by opening or trying to open the casing  200  through various routes. 
     Alternatively, to protect the security unit  600  provided as the central processing unit for processing data or the storage medium for sorting data, the security partition  700  may be formed in a shape of encompassing the security unit  600  in a closed type or an open type. 
     In other words, for a closed type, the security partition  700  is provided to encompass the entire perimeter of the security unit  600 . For an open type, the security partition  700  is provided to encompass the perimeter of the security unit  600  with a part of the security partition  700  opened. 
     As illustrated in  FIG. 1 , the security partition  700  may be provided to encompass the security unit  600  in a closed type A. 
     In other words, since the central processing unit and the storage medium are where important data is processed and stored, a physical shock transferred to the security unit  600  from the outside may be prevented by the security partition  700  that encompasses the security unit  600 . 
     Also, to protect a connection socket  800  arranged inside the casing  200 , the security partition  700  may be formed in a shape of encompassing the connection socket  800  in a closed type or open type. 
     In the connection socket  800 , like the security unit  600 , for a closed type, the security partition  700  is provided to encompass the entire perimeter of the connection socket  800  and, for an open type, the security partition  700  is provided to encompass the perimeter of the connection socket  800  in a state in which a part of the security partition  700  is open. 
     As illustrated in  FIG. 1 , the security partition  700  may be provided to encompass the connection socket  800  in an open type B. 
     Alternatively, when the resistance value of the anti-tampering conduction portion  400  is out of a preset range, or the resistance value of the anti-tampering conduction portion  400  becomes infinite, thereby disconnecting the electric connection between the anti-tampering conduction portion  400  and the circuit board  300 , the mobile terminal  100  provided with a security function according to an exemplary embodiment may be capable of generating alarm sound. 
     The operation and effect of the mobile terminal  100  provided with a security function according to the exemplary embodiment are described below. 
     First, referring to  FIGS. 1 and 2 , the upper circuit board  310  and the lower circuit board  320  are arranged between the upper casing  210  and the lower casing  220 . The anti-tampering prevention members  410  are arranged between the upper circuit board  310  and the lower circuit board  320 . The anti-tampering prevention members  410  are pressed by the coupling member  240  that penetrates through the upper casing  210  and the lower casing  220 . 
     The upper security partition  710  connected to the upper circuit board  310  and the lower security partition  720  connected to the lower circuit board  320  may be arranged between the upper circuit board  310  and the lower circuit board  320 . 
     The anti-tampering conduction portion  400  may be supported by being inserted into the accommodation opening  730  formed in the upper security partition  710  and the lower security partition  720 . 
     The anti-tampering conduction portion  400  is electrically connected to at least two of the upper circuit board  310 , the lower circuit board  320 , the upper security partition  710 , and the lower security partition  720 . When access to or an attempt to access to the data of the security unit  600 , for example, opening or trying to open the casing  200  by an external force, occurs, access to the data of the security unit  600  is denied by erasing preset important data. As a result, leakage of important data to the outside may be prevented. 
     While this inventive concept has been particularly shown and described with reference to preferred 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 inventive concept as defined by the appended claims. Therefore, the scope of the inventive concept is defined not by the detailed description of the inventive concept but by the appended claims, and all differences within the scope will be construed as being included in the present inventive concept. 
     INDUSTRIAL APPLICABILITY 
     The present inventive concept is applicable to mobile communication terminals, payment terminals, and various computers and tablet PCs, and particularly, to the payment terminal industry.
Disclosed is a mobile terminal provided with a security function. The mobile terminal provided with the security function can include: a casing having a data input portion for inputting data, and an upper casing and a lower casing which can be assembled and disassembled; a circuit board for processing input data, which is electrically connected to the data input portion and is provided with a security unit that requires security; a tamper prevention conductive portion which is arranged between the casing and the circuit board and is electrically connected to the circuit board when the upper casing and the lower casing are assembled; and a control portion for denying access to data in the security unit based on a resistance value of the tamper prevention conductive portion. As a result, access to data in a secure region to which important data is saved is denied when the casing is forcibly opened, thereby effectively preventing important data from being leaked to the outside.