Abstract:
Disclosed herein are a digital video receiver which supports a High Definition Multimedia Interface (HDMI) standard, and a display method thereof. The digital video receiver includes an HDMI receiver including a memory for storing HDMI information, and a High-bandwidth Digital Content Protection (HDCP) module. As such, it is possible to flexibly cope with an authentication error in an HDCP connection and very stably protect digital video contents.

Description:
[0001]     This application claims the benefit of Korean Patent Application No. 10-2005-0090677, filed on Sep. 28, 2005, which is hereby incorporated by reference as if fully set forth herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a digital video receiver which decrypts encrypted digital video data, and a display method thereof.  
         [0004]     2. Discussion of the Related Art  
         [0005]     Recently, standards, such as High Definition Multimedia Interface (HDMI) and Digital Visual Interface (DVI), have been employed for transmission and reception of digital video data between a digital video transmitter and a digital video receiver.  
         [0006]     A High-bandwidth Digital Content Protection (HDCP) standard has been applied to digital video data being transmitted and received on the basis of the above standards, such that the digital video data is advantageously resistant to unauthorized duplication thereof.  
         [0007]     In general, a display system comprises a digital video transmitter and a digital video receiver, and is adapted to receive a multimedia signal including video and audio and output the received multimedia signal in the form of an image and sound through a display unit.  
         [0008]     In order to support the aforementioned standard (HDMI or DVI), the digital video transmitter and digital video receiver of the display system must be able to support the corresponding standard.  
         [0009]     However, generally, the digital video receiver must have, in the form of a separate chip, a non-volatile memory which stores information regarding the display unit, which is a kind of display means, and also have an extended I 2 C communication module chip with two pull-up resistors to read standard information from the memory.  
         [0010]     As a result, the general digital video receiver is disadvantageous in that it additionally has the I 2 C communication module chip and the memory chip, resulting in a complexity in driving circuit and an increase in cost. Further, an I 2 C communication path becomes complicated, thereby increasing the possibility that an error will occur during I 2 C communication.  
         [0011]     In addition, the general digital video receiver has poor flexibility for an error in an HDCP connection and protection of digital contents.  
       SUMMARY OF THE INVENTION  
       [0012]     Accordingly, the present invention is directed to a digital video receiver and a display method thereof that substantially obviate one or more problems due to limitations and disadvantages of the related art.  
         [0013]     An object of the present invention is to provide a digital video receiver which has a simple structure to realize excellent flexibility for an error in an HDCP connection and protection of digital contents, and a display method thereof.  
         [0014]     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
         [0015]     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a digital video receiver comprises: a display unit; a display controller for providing video data to the display unit; and a High Definition Multimedia Interface (HDMI) receiver including a memory for storing HDMI information, and a High-bandwidth Digital Content Protection (HDCP) module.  
         [0016]     The HDMI information may include extended display identification data (EDID) information, and an HDCP authentication key, which may be encrypted when being stored in the memory.  
         [0017]     The HDMI receiver may further include: an information detector for detecting the information stored in the memory; and an information updater for changing the information stored in the memory, and the HDCP module may comprise: a public key creator for reading and decrypting the encrypted HDCP authentication key stored in the memory to create a public key; and a decrypter for decrypting inputted digital video data using the created public key.  
         [0018]     The HDCP module may further comprise a user encryption key setter for setting a user encryption key using the created public key according to a user&#39;s setting, and a scheme for decrypting the authentication key by the public key creator may be re-set by changing the user encryption key.  
         [0019]     The display controller may comprise: an error detector for detecting an authentication error of the HDCP module; and a command sender for sending a pause signal or pause release signal to the display unit, and the memory may be a non-volatile memory (NVM).  
         [0020]     In another aspect of the present invention, a display method of a digital video receiver comprises: (a) performing an HDCP authentication to decrypt inputted digital video data; (b) periodically checking presence/absence of an error in an HDCP connection; and (c) displaying the decrypted digital video data.  
         [0021]     The step (a) may comprise: reading and decrypting an HDCP authentication key to create a public key; decrypting the inputted video data using the created public key; and setting a user encryption key using the created public key according to a user&#39;s setting.  
         [0022]     The step (b) may comprise: determining whether the error in the HDCP connection is present in the digital video receiver; and sending a pause signal if it is determined that the error in the HDCP connection is present in the digital video receiver, and the error may include an error in the HDCP authentication.  
         [0023]     The step (c) may comprise pausing or normally displaying the decrypted digital video data in response to a command signal sent at the step (b).  
         [0024]     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  
       [0025]     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 embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:  
         [0026]      FIG. 1  is a block diagram showing the configuration of a display system with a digital video receiver according to one embodiment of the present invention;  
         [0027]      FIG. 2  is a block diagram of an HDMI-receiver in  FIG. 1 ;  
         [0028]      FIG. 3  is a block diagram of an HDCP module in  FIG. 2 ;  
         [0029]      FIG. 4  is a flowchart illustrating a display method of the digital video receiver according to one embodiment of the present invention; and  
         [0030]      FIG. 5  is a flowchart illustrating the step of decrypting digital video data in  FIG. 4 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0031]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
         [0032]      FIG. 1  is a block diagram showing the configuration of a display system with a digital video receiver according to one embodiment of the present invention.  
         [0033]     As shown in  FIG. 1 , the display system comprises a digital video transmitter  100  including an HDMI-transmitter  10  for providing encrypted digital video data, a digital video receiver  200  including an HDMI-receiver  20  for decrypting the digital video data received from the digital video transmitter  100 , and a display unit  300  for outputting the digital video data decrypted by the digital video receiver  200 . The digital video transmitter  100  and the digital video receiver  200  are interconnected via an I 2 C bus based on a serial protocol, such as I 2 C.  
         [0034]     In an HDCP standard, the HDMI-transmitter  10 , which transmits the digital video data, and the HDMI-receiver  20 , which receives the digital video data, authenticate each other using a public key encryption scheme, and the HDMI-transmitter  10  then encrypts and transmits the digital video data to the HDMI-receiver  20 .  
         [0035]     For the authentication and encryption, the digital video transmitter  100  and the digital video receiver  200  share their respective public keys with each other. A private key concealed in each of them is called a device key.  
         [0036]     Accordingly, if the authentication is successful between the digital video transmitter  100  and the digital video receiver  200 , the digital video transmitter  100  encrypts and transmits the digital video data using its device key, and the digital video receiver  200  receives and decrypts the digital video data using its device key. Then, the display unit  300  outputs the decrypted digital video data through a screen or speaker.  
         [0037]     Optionally, using a created public key, the user may set encryption and store a user encryption key. In this case, the user encryption key may be stored in an allocated area of a register  60  or an internal memory of the HDMI-receiver  20 .  
         [0038]      FIG. 2  is a block diagram of the HDMI-receiver  20  in  FIG. 1 .  
         [0039]     As shown in  FIG. 2 , the HDMI-receiver  20  includes an information detector  21 , a memory  22 , and an information updater  23 .  
         [0040]     The HDMI-receiver  20  further includes an HDCP module  24  for performing the HDCP authentication as stated above. The memory  22  is a non-volatile memory, which may be any one of a flash memory or electrically erasable programmable read only memory (EEPROM).  
         [0041]     The HDCP module  24  performs the encryption authentication in communication with the HDMI-transmitter  10 , as stated previously.  
         [0042]     The memory  22  of the HDMI-receiver  20  stores information indicative of HDMI supportability/nonsupportability of the display unit  300 , which is incorporated in the digital video receiver  200  or externally connected thereto.  
         [0043]     The HDMI-transmitter  10  reads the information indicative of the HDMI supportability/nonsupportability of the display unit  300  from the memory  22  of the HDMI-receiver  20  and determines from the read information whether the display unit  300  supports an HDMI standard.  
         [0044]     The information detector  21  functions to, when the HDMI-transmitter  10  reads information from the HDMI-receiver  20 , detect that information (for example, the information indicative of the HDMI supportability/nonsupportability of the display unit  300 ) from the memory  22 .  
         [0045]     In more detail, as stated above, the reading of information from the memory  22  of the HDMI-receiver  20  by the HDMI-transmitter  10  is carried out through communication between the HDMI-transmitter  10  and the HDMI-receiver  20 .  
         [0046]     That is, in the present embodiment, the HDMI-receiver  20  notifies the HDMI-transmitter  10  of the HDMI supportability/nonsupportability of the display unit  300  in communication with the HDMI-transmitter  10 . At this time, the information detector  21  of the HDMI-receiver  20  detects the information indicative of the HDMI supportability/nonsupportability of the display unit  300  from the memory  22  in response to a request from the HDMI-transmitter  10 . The information detector  21  then transmits the detected information to the HDMI-transmitter  10 .  
         [0047]     Here, the HDMI-receiver  20  transmits extended display identification data (EDID) to the HDMI-transmitter  10  using a signal protocol proposed in an EDID standard.  
         [0048]     Also, the aforementioned encryption authentication is carried out through communication between the HDMI-transmitter  10  and the HDCP module  24  included in the HDMI-receiver  20 .  
         [0049]     At this time, the information detector  21  of the HDMI-receiver  20  detects an encryption authentication key stored in the memory  22 . Then, the encryption authentication is performed using the detected authentication key.  
         [0050]     Meanwhile, the information updater  23  included in the HDMI-receiver  20  is operated for change of data stored in the memory  22 . Here, the data stored in the memory  22  is the information indicative of the HDMI supportability/nonsupportability and/or encryption authentication key.  
         [0051]     The information updater  23  is operated under an external control (for example, a control applied by an operation of a manufacturer of a digital video player).  
         [0052]     According to the present embodiment, the display system with the digital video receiver  200  adopts an Inter Integrated Circuit (I 2 C) bus for I 2 C communication between the HDMI-transmitter  10  and the HDMI-receiver  20 . The I 2 C bus consists of two communication lines to support communication of two types of signals between the HDMI-transmitter  10  and the HDMI-receiver  20 .  
         [0053]     An I 2 C communication module chip including two pull-up resistors  50  is used for the I 2 C communication between the HDMI-transmitter  10  and the HDMI-receiver  20 .  
         [0054]     In the above-described configuration according to the present embodiment, the HDMI-transmitter  10  reads information (the information indicative of the HDMI supportability/nonsupportability) regarding the display unit  300  from the HDMI-receiver  20  through the I 2 C communication therewith and determines from the read information whether the display unit  300  supports the HDMI standard.  
         [0055]     On the other hand, the aforementioned information indicative of the HDMI supportability/nonsupportability is extended display identification data (EDID). The encryption authentication key is encrypted when being stored in the memory  22 , such that the encryption authentication key stored in the memory  22  does not flow out of the memory  22  in the process of reading or writing the EDID from/into the memory  22  by the information detector  21  or information updater  23 .  
         [0056]      FIG. 3  is a block diagram of the HDCP module  24  in  FIG. 2 .  
         [0057]     As shown in  FIG. 3 , the HDCP module  24  includes a public key creator  31  for reading and decrypting the encrypted authentication key from the memory  22  to create a public key, an HDCP decrypter  32  for decrypting an inputted digital signal using the created public key, and a user encryption key setter  33  for setting a user encryption key using the created public key.  
         [0058]     The user encryption key setter  33  acts to set the user encryption key using the created public key of the authentication key so that the user can optionally set encryption. The public key creator  31  acts to decrypt the authentication key using the user encryption key set by the user encryption key setter  33 .  
         [0059]     Moreover, a scheme for decrypting the authentication key by the public key creator  31  can be re-set by changing the user encryption key.  
         [0060]     At this time, the optionally set user encryption key can be stored in the memory  22  included in the HDMI-receiver  20  or an allocated area of the register  60 .  
         [0061]      FIG. 4  is a flowchart illustrating a display method of the digital video receiver  200  according to one embodiment of the present invention.  
         [0062]     First, the HDMI-transmitter  10  in the digital video transmitter  100  determines whether the HDMI-receiver  20  in the digital video receiver  200  supports the HDMI standard, through the I 2 C communication with the HDMI-receiver  20  ( 400 ).  
         [0063]     If the HDMI-transmitter  10  determines that the HDMI-receiver  20  supports the HDMI standard, the HDMI-receiver  20  decrypts digital video data inputted to the digital video receiver  200  through the HDCP authentication ( 401 ).  
         [0064]     Then, a display controller  30  included in the digital video receiver  200  periodically checks the presence/absence of an authentication error in an HDCP connection at an interval of about two seconds ( 402 ). If no authentication error is present, the display controller  30  proceeds directly to step  405  of displaying the decrypted digital video data. If an authentication error is present, the display controller  30  sends a pause command signal to pause at the current state ( 403 ).  
         [0065]     Here, the checking of the presence/absence of an authentication error includes checking the presence/absence of a hot plug detection (HPD) signal.  
         [0066]     Next, if the user recognizes the pause state and then inputs a pause release command, the display controller  30  releases the pause state ( 404 ) and then displays the decrypted digital video data through the display unit  300  ( 405 ).  
         [0067]      FIG. 5  is a flowchart illustrating step  401  of decrypting digital video data in  FIG. 4 .  
         [0068]     First, a public key is created by reading and decrypting an HDCP authentication key ( 501 ). As stated previously with reference to  FIG. 1 , for the authentication and encryption, the digital video transmitter  100  and the digital video receiver  200  share their respective public keys with each other. A private key concealed in each of them is called a device key.  
         [0069]     Meanwhile, the user may optionally set a user encryption key using the created public key. For this reason, after the above step  501  is performed, a determination is made as to whether a user encryption key has been set ( 502 ) before the inputted digital video data is decrypted using the created public key ( 504 ). If it is determined that a user encryption key has been set, the set user encryption key is inputted ( 503 ). If it is determined that no user encryption key has been set, the inputted digital video data is decrypted ( 504 ) and then outputted to the display unit  300 .  
         [0070]     Here, the user encryption key may be stored in an allocated area of the register  60  included in the digital video receiver  200  or the memory  22  included in the HDMI-receiver  20 .  
         [0071]     Although the interface between the digital video transmitter  100  and the digital video receiver  200  has been disclosed in the present embodiment to be the HDMI, it may be a digital visual interface (DVI).  
         [0072]     As apparent from the above description, according to the present invention, the information (EDID) indicative of the HDMI supportability/nonsupportability of the digital video receiver is stored in the memory included in the HDMI-receiver without using an additional I 2 C communication module chip or memory, thereby making it possible to simplify a driving circuit of the digital video receiver.  
         [0073]     In addition, it is possible to curtail the manufacturing cost of the digital video receiver and significantly reduce the possibility that an error will occur during I 2 C communication between the digital video transmitter and the digital video receiver.  
         [0074]     Furthermore, it is possible to flexibly cope with an authentication error in an HDCP connection and very stably protect digital video contents.  
         [0075]     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. 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.