MULTI-FUNCTIONAL PINPAD Technical Field [1] The present invention relates, in general, to a pinpad and, more particularly, to a multi-functional pinpad which supports various transaction methods using a magnetic card, an integrated circuit card and a mobile terminal, and which provides support such that any one is selected from among a keypad, a fingerprint recognition sensor and a universal serial bus interface, and authentication can be performed using the selected one. Background Art [2] Generally, an apparatus, such as a financial terminal, which prevents some persons from illegally connecting to and using it, is configured such that a password is previously assigned to each user, the password is input before a financial processing function is conducted, whether the input password is identical to the previously assigned password is determined, and then the following step is processed if the passwords are identical to each other, in order to allow only permitted users to manipulate the apparatus under normal circumstances. [3] However, since a conventional pinpad receives a password through a keypad and then performs authentication according to whether the input password is identical to a registered password, a security problem exists in that a process of inputting a password may be visible to some persons. Disclosure of Invention Technical Problem [4] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a pinpad, to which an LCD equipped with a privacy filter through which light perpen¬ dicularly incident on the display unit of the pinpad passes, but light obliquely incident on it does not pass, is provided, so that only the person who himself or herself inputs a password can confirm the password, and adjacent persons can not watch a process of inputting a password. [5] Another object of the present invention is to provide a pinpad that makes the financial transactions of customers convenient by supporting various transaction methods that use magnetic cards, Integrated Circuit (IC) cards and mobile terminals. [6] A further object of the present invention is to provide a pinpad that allows au¬ thentication to be performed by using any one selected from among a keypad, a fingerprint recognition sensor and a Universal Serial Bus (USB) interface, so that the security of the authentication is enhanced. Technical Solution [7] In order to accomplish the above objects, the present invention provides a multi¬ functional pinpad, including a magnetic card reading module for reading financial in¬ formation from magnetic card that contains the financial information; an Integrated Card (IC) processing module for reading financial information from an IC card that contains the financial information, and having a Smart Access Memory (SAM) chip required for storing authentication and transaction details at the time of a credit purchase; a mobile terminal communication module for receiving financial information from a mobile terminal that transmits the financial information using any one selected form among an infrared type optical signal, an Radio Frequency (RF) signal, and a bluetooth method; a transaction method selection unit for selecting any one module from among the magnetic card reading module, the IC card processing module, the mobile terminal communication module, and conducting transactions using the selected module; a keypad for receiving a password from a user; a fingerprint recognition sensor for receiving a fingerprint from the user; a Universal Serial Bus (USB) interface for receiving authentication data from a USB memory stick in which the authentication data are stored; an authentication method selection unit for performing authentication by selecting any one from among the keypad, the fingerprint recognition sensor, and the USB interface; an encryption unit encrypting the password, the fingerprint, and the authentication data; and a transmission unit for transmitting the encrypted data to a financial terminal. [8] Furthermore, the functional pinpad according the present invention further includes a display unit for displaying a transaction method selection screen, an authentication method selection screen, and a password input screen. [9] Furthermore, the display unit is a Liquid Crystal Display (LCD) equipped with a privacy filter through which light perpendicularly incident passes, but light obliquely incident does not pass. [10] Furthermore, the functional pinpad according the present invention further includes a voice guidance unit for guiding transaction method selection, authentication method selection, and password input using a voice. [11] Furthermore, the encryption module encrypts the password, the fingerprint, and the authentication data using a Triple Date Encryption Standard (DES) encryption algorithm. [12] Furthermore, the functional pinpad according the present invention further includes a USB sub interface for connecting with external peripheral devices, such as an external fingerprint recognition module Advantageous Effects [13] The multi-functional pinpad according to the present invention is provided with an LCD equipped with a privacy filter through which light perpendicularly incident on the display unit of the pinpad passes, but light obliquely incident on it does not pass, so that only the person who himself or herself inputs a password can confirm the password while inputting it, and adjacent persons cannot watch a process of inputting a password, thus enhancing security. [14] Furthermore, the multi-functional pinpad according to the present invention can make the financial transactions of customers convenient by supporting various transaction methods that use magnetic cards, IC cards and mobile terminals. [15] Furthermore, the multi-functional pinpad according to the present invention allows authentication to be performed by using any one selected from among a keypad, a fingerprint recognition sensor and a USB interface, so that the security of au¬ thentication is enhanced. Brief Description of the Drawings [16] FIG. 1 is a block diagram showing a multi-functional pinpad according to the present invention; [17] FIG. 2 is a view showing the appearance of a multi-functional pinpad product; [18] FIG. 3 is a view showing a transaction method selection screen; and [19] FIG. 4 is a view showing an authentication method selection screen. Best Mode for Carrying Out the Invention [20] A preferred embodiment of the present invention is described in detail with reference to the accompanying drawings below. [21] FIG. 1 is a block diagram showing a multi-functional pinpad according to the present invention, and FIG. 2 is a view showing the appearance of a multi-functional pinpad product 100. [22] Referring FIGS. 1 and 2, the multi-functional pinpad 100 according to the present invention includes a transaction method selection unit 110, an authentication method selection unit 120, an encryption unit 130, a transmission unit 140, a display unit 150 and a voice guidance unit 160. [23] The transaction method selection unit 110 includes a magnetic card reading module 112 for reading financial information from a magnetic card containing the financial in¬ formation, an IC card processing module 114 for reading financial information from an IC card containing the financial information and having a SAM chip required for storing authentication and transaction details at the time of a credit purchase, and a mobile terminal communication module 116 for receiving financial information from a mobile terminal transmitting the financial information using at least one of an infrared type optical signal, an RF signal, and a bluetooth method. The transaction method selection unit 110 selects any one module from among the magnetic card reading module 112, the IC card processing module 114 and the mobile terminal com¬ munication module 116, and then performs transactions using the selected module. [24] The authentication method selection unit 120 includes a keypad 122 for receiving a password from a user, a fingerprint recognition sensor 124 for receiving a fingerprint from the user, and a USB interface 126 for receiving authentication data from a USB memory stick in which the authentication data have been stored. The authentication method selection unit 120 selects any one from among the keypad 122, the fingerprint recognition sensor 126 and the USB interface 126 and then performs authentication. [25] The encryption unit 130 encrypts a password input through the keypad 122, a fingerprint received from the fingerprint recognition sensor 124 or the authentication data received through the USB interface 126. [26] The transmission unit 140 transmits data, which are encrypted by the encryption unit 130, to a financial terminal 200. [27] Meanwhile, the display unit 150 displays a transaction method selection screen, an authentication method selection screen and a password input screen, and is formed of an LCD that is equipped with a privacy filter through which light perpendicularly incident passes, but light obliquely incident does not pass. [28] Furthermore, the voice guidance unit 160 guides transaction method selection, au¬ thentication method selection and password input using voice, and the guide voice is stored in the memory (not shown) of the pinpad in a small size MPEG Layer-3 (MP3) format. [29] The operation of the multi-functional pinpad according to the present invention is described in detail below. [30] FIG. 3 is a view showing a transaction method selection screen, and FIG. 4 is a view showing an authentication method selection screen. [31] Referring to FIGS. 3 and 4, when a bank teller selects the type of a transaction, such as deposits, withdrawals, transfers to other banks, or cash loan service, through the financial terminal 200, the transaction method selection screen shown in FIG. 3 is displayed on the display unit 150 of the multi-functional pinpad 100 that has been connected with the financial terminal 200 through a USB connector cable or the like. At the same time, the voice guidance unit 160 may emit transaction method selection guiding messages in voice form. [32] Thereafter, a customer selects a desired transaction method using the keypad 122. [33] The customer presses a button No. 1 on the keypad 122 when desiring to conduct a transaction using a magnetic card. When the button No. 1 is pressed, the magnetic card reading module 122 operates and read the customer's magnetic card, thus reading financial information, such as an account number, from the magnetic card. [34] The customer presses a button No. 2 on the keypad 122 when desiring to conduct transactions using an IC card, the IC card processing module 114 operates and read the customer's IC card, thus reading financial information, such as an account number, from the IC card. Several pieces of account information may be stored in the IC card. Accordingly, when several pieces of financial information, such as account numbers, are first read, the read account numbers are displayed on the display unit 150. Thereafter, when the customer selects a specific account number, transactions using the corresponding account number are performed. Particularly, in the case of a credit purchase, the credit purchase is authorized using the SAM chip, the transaction details thereof are stored, and information about the transaction details is transmitted to a server when the number of transactions reaches a predetermined number. [35] The customer presses a button No. 3 on the keypad 122 when desiring to conduct transactions using a mobile terminal that transmits the financial information using at least one of an infrared type optical signal, an RF signal, a bluetooth method. When the button No. 3 is pressed, the mobile terminal communication module 116 receives financial information, such as an account number, from the customer's mobile terminal. Several pieces of account information may be stored in the mobile terminal. Ac¬ cordingly, when several pieces of financial information, such as account numbers, are first read, the read account numbers are displayed on the display unit 150. Thereafter, when the customer selects a specific account number, transactions using the cor¬ responding account number are performed. [36] After the customer selects a transaction method by selecting one from among the magnetic card, the IC card and the mobile terminal described above, the authentication method selection screen shown in FIG. 4 is displayed. The voice guidance unit 160 may also emit transaction method selection guiding messages in voice form. [37] Referring to FIG. 4, the customer presses the button No. 1 on the keypad 122 when desiring to use a password authentication. When the button No. 1 is pressed, the password input screen is displayed on the display unit 150 and, at the same time, the voice guidance unit 160 emits password input guiding messages in voice form. Thereafter, the customer inputs his/her password through the keypad. [38] The customer presses the button No. 2 on the keypad 122 when desiring to use fingerprint authentication. When the button No. 2 is pressed, the fingerprint recognition sensor 124 operates. In this case, when the customer brings his or her fingerprint into contact with the fingerprint recognition sensor 124, the fingerprint recognition sensor 124 recognizes the fingerprint. Furthermore, the multi-functional pinpad of the present invention includes a USB sub interface (not shown), and is configured so that the fingerprint recognition module 124 may be replaced by an external fingerprint recognition module by connecting the external fingerprint recognition module to the USB sub interface and using it. [39] The customer presses the button No. 3 on the keypad when desiring to be authorized using a USB memory stick in which authentication data has been stored. When the button No. 3 is pressed, the authentication data are retrieved from the USB memory stick inserted into the USB interface 126. [40] As described above, when the authentication method selection unit 120 receives the password, the fingerprint, or the authentication data, the encryption unit 130 encrypts the password, the fingerprint, or the authentication data using the Triple Date Encryption Standard (DES) encryption algorithm and then transmits the encrypted data to the transmission unit 140. The transmission unit 140 transmits the encrypted data to the financial terminal 200, so that the financial terminal 200 can perform au¬ thentication after decrypting the encrypted data. [41] When the authentication is completed, the bank teller can handle transactions, such as deposits, withdrawals, transfers to other banks, and cash loan service, through the financial terminal 200, and transaction details may be displayed on the display unit 200 of the pinpad 100.