BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The invention relates to an extendable interface and method and, in particular, to an extendable interface and method for digital televisions.  
         [0003]     2. Related Art  
         [0004]     Mass transmission of digital data is the most important thing in future knowledge economics. In particular, the rapid development and growth in software and hardware industries pushed by the digital television (TV) have brought enormous economical benefits to the countries all over the world. Thus, this area of industry has received much attention in these years.  
         [0005]     As shown in  FIG. 1 , a conventional digital TV can be divided into the following parts: a back end  100 , a front end  110 , a network service module  120 , and a storage memory module  130 . The back end  100  processes received digital data and has a form basically the same as a personal computer system, including a central processing unit (CPU)  101 , a dynamic memory module  102 , a conditional access module  103 , an audio/video (AV) player module  104 , an audio decoding module  105 , and a video decoding module  106  to achieve the real-time playing, arbitrary recording/playing, conditional playing, and interactive services. The front end  110  provides the functions of signal demodulation and channel control, including a demodulation module  111  and a channel selection module  112 . The network service module  120  is a basic module that enables the digital TV to have an interactive service mechanism. The storage memory module  130  stores the software required by the digital TV so that it can keep data even when the digital TV is turned off.  
         [0006]     The above-mentioned basic structure of the digital TV may be added with additional features according to the user&#39;s needs or provided services. However, these digital TV structures usually are not extendable and flexible. Therefore, if the user has new needs or the provided services change, the only choice is to purchase a new one. This is not only a big financial burden for the users, the development of digital TV&#39;s is also restricted.  
         [0007]     For example, the existing digital TV&#39;s have many different systems, each of which has a distinct modulation method. In addition to the rough classifications of the European standard, the American standard, and the IPTV standard, the European standard and the American standard are further divided into surface broadcasting, wired broadcasting, and satellite broadcasting. If the user purchases a digital TV of the European standard with the surface broadcasting, it is impossible to switch to the American standard with the wired broadcasting without purchasing a new digital TV. It is very impractical. The same situation also happens when the user want to add new interactive services to the digital TV. For example, if the user wants to switch from the ADSL service to the cable modem service, a new digital TV is required due to the different network services provided by the providers or the different linking networks. When the hardware structure of a digital TV is changed, the require software has to be changed too in order for the TV to work properly. This situation can be seen from the difference between  FIGS. 2A and 2B . When the digital TV is equipped with network services, the software that has to be stored in the storage memory module  130  includes: the real-time operating system (OS)  131 , the middleware  132 , and various kinds of applications  133 . On the other hand, if the digital TV is not equipped with network services, the storage memory module  130  only needs to hold the real-time OS  131  and playing software  134 .  
         [0008]     All these problems show that the conventional digital TV structure is in lack of flexibility and convenience in extensions. As a result, users are more hesitant to select and purchase. This definitely will affect the future development of the digital TV industry. If one wants to fully solve the existing problems in the digital TV structure, it is imperative to provide a method for improving its extendibility. This is believed to greatly increase user&#39;s will to purchase the products.  
         [0009]     Although a digital TV with an extendable system card has been proposed in the R.O.C. Pat. No. 541,836, it is mainly to provide an interface for conditional access on the digital TV. The digital TV can therefore execute applications on this interface to achieve the control of conditional access. In the U.S. Pat. No. 6,101,368, an interface for bidirectional communications between an external device and the digital TV is proposed so that the external device can control and access the digital TV. Each of these prior arts provides an interface that can be combined with the digital TV. However, they are restricted to the extension of a specific function of the digital TV, instead of a universal extendable interface. Consequently, their effects in solve the existing problem in digital TV&#39;s are very limited. We are still in need of an extendable interface for the digital TV.  
       SUMMARY OF THE INVENTION  
       [0010]     In view of the foregoing, an objective of the invention is to provide a consistent extendable interface and method for digital TV&#39;s. In particular, the front end, the network service module and the storage memory module are provided for the user to have a convenient extendable interface. Any other extendable peripheral compliant with the defined extension interface standard can be extended using the disclosed extendable interface.  
         [0011]     The disclosed extendable interface for the digital TV includes: a power supply port, a control signal port, a serial bus, a parallel bus, and a signal transport port.  
         [0012]     The disclosed method of extending the digital TV includes the steps of: connecting an extendable peripheral to the back end of the digital TV; providing a power supply port for the back end to provide power to the extendable peripheral; providing a control signal port for the back end to control, set, and identify the extendable peripheral; providing a serial bus for the back end to initialize settings and access bi-directional data on the extendable peripheral; providing a parallel port for the back end to perform bi-directional data access with the extendable peripheral; and providing a signal transport port for the back end to receive signals from the extendable peripheral.  
         [0013]     The required methods for implementing communications between each extendable peripheral and the back end of a digital TV may not be completely the same. In addition to the power supply of the power supply port and the control, setting, and identification provided by the control signal port, the operations of the serial bus, the parallel bus, and the signal transport port can be selectively chosen to form links with the back end according to one&#39;s needs.  
         [0014]     Using the invention, the user can use a consistent interface to extend the applications of the digital TV. Moreover, one interface can support the extension of more than one function. This can increase the convenience of the digital TV and the development of the industry. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The invention will become more fully understood from the detailed description given hereinbelow illustration only, and thus are not limitative of the present invention, and wherein:  
         [0016]      FIG. 1  is a schematic view of the conventional digital TV structure;  
         [0017]      FIG. 2A  is a schematic view of the software contents stored in the storage memory module when the digital TV is equipped with network services;  
         [0018]      FIG. 2B  is a schematic view of the software contents stored in the storage memory module when the digital TV is not equipped with network services;  
         [0019]      FIG. 3  is a schematic view of the digital TV structure with the disclosed extendable interface; and  
         [0020]      FIG. 4  is a flowchart of the disclosed extension method of extendable interface for the digital TV.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     The disclosed extendable interface  200  for the digital TV mainly provide a link between the back end of the digital TV and a connected extendable peripheral, such as the front end  110 , the network service module  120 , and the storage memory module  130 . This facilitates various extensions of the digital TV. Its general structure includes the following elements:  
         [0022]     (1) A power supply port  210  is used to provide power from the back end  100  to the connected extendable peripheral. The supplied power is mainly the well-known 30V, 12V, 5V, 3.3V and the ground GND.  
         [0023]     (2) A control signal port  220  is used to provide the back end  100  controls, settings, and identification of the extendable peripheral. The common control signals include: the control signal of executing the control signals for the extendable peripheral, restart, or reset; the interrupt signal of controlling the central processing unit (CPU)  101  to execute a routine interrupt and a new request; the identification signal of providing the back end  100  of the digital TV as a means to identify the extendable peripheral.  
         [0024]     (3) A serial bus  230  is used to enable the back end  100  to initialize the settings and perform bi-directional data access on the extendable peripheral. For example, the channel selection module  112  in the front end  110  is initialized by the back end  100  through this serial bus. A general serial bus  230  is an Inter  1 C ( 1   2 C) bus or a serial peripheral interface (SPI) bus.  
         [0025]     (4) A parallel bus  240  is used to allow the bidirectional data access between the back end  100  and the extendable peripheral. The signal types commonly used in the parallel bus  240  include: the address bus signal, the data bus signal, the read/write (R/W) signal, the OE signal, the ready signal, the chip select signal, and the write enable byte  0  signal.  
         [0026]     (5) A signal transport port  250  is used to enable the back end  100  to receive signals transmitted from the extendable peripheral. For example, the front end  110  transmits the signal transport flow demodulated by a demodulation module  111  via this signal transport port to the back end  100 . The signals in the signal transport flow include: the clock synchronization signal CLK, the packet synchronization signal SYNC, the packet signal Valid, the data signal Data, and the error signal Error.  
         [0027]     Using the above structure, the combination of the disclosed extendable interface  200  and the digital TV, as illustrated in  FIG. 3 , allows the extensions of the front end  110 , the network service module  120 , the storage memory module  130 , or any other extendable peripheral according to the different needs. The extension method is further described using  FIG. 4 .  
         [0028]     First, the extendable peripheral is electrically connected to the back end  100  of the digital TV (step  300 ). A power supply port  210  is then provided for the back end  100  to provide power to the extendable peripheral (step  310 ). A control signal port  220  is provided for the back end  100  to control, set, and identify the extendable peripheral (step  320 ). Basically, all the extendable peripherals have to be power supplied and monitored by the back end  100 . Therefore, steps  310  and  320  are mandatory.  
         [0029]     Other steps depend on the type of the extendable peripheral and are executed selectively. First, the system checks whether the extendable peripheral is already connected to the serial bus  230  (step  330 ). If so, then the serial bus  230  is provided for the back end  100  to initialize settings and bi-directional data access on the extendable peripheral (step  340 ). Otherwise, the system directly checks whether the extendable peripheral has connected to the parallel port  240  (step  350 ). If so, the parallel port  240  is provided for the back end  100  to perform bi-directional data access with the extendable peripheral (step  360 ). Otherwise, the system directly provides a signal transport port  250  for the back end  100  to receive signals transmitted from the extendable peripheral (step  370 ).  
         [0030]     It is thus seen that aside from steps  310  and  320 , other steps in the disclosed method may or may not be necessary for different kinds of extendable peripherals connected to the extendable interface  200  for the digital TV.  
         [0031]     For example, suppose the extendable peripheral is the front end  110  of the digital TV. Since channel selection information needs to be exchanged between the back end  100  and the front end  110 , step  340  has to be performed. Moreover, the front end  110  has to demodulate the received digital TV signal into a signal transport flow before sending it to the back end  100 . Therefore, step  370  has to be executed too. Step  360 , on the other hand, is not necessary. The user can thus change the standard and transmission method of the digital TV system by extending its front end  110 .  
         [0032]     Suppose the extendable peripheral enables bi-directional interactive services, such as a network service module  120  that provides video-telephone, online games, stock transactions, online shopping, information services, etc, the serial bus  230  has to be provided. That is, step  340  has to be executed for the back end  100  to perform bi-directional data access with the network services provided by the network service module  120 . The user can freely select the required network connection type when extending its network service module  120 , e.g. ADSL, Ethernet, cable modem, PSTN, GPRS, etc.  
         [0033]     Suppose the extendable peripheral to be connected is a storage memory module  130  for storing the software program required by the back end  100 , then step  360  is mandatory to provide the parallel port as a channel for the storage memory module  130  and the back end  100  to exchange data. The user can update the software contents, including the real-time OS  131 , the middleware, various applications, and the playing software, in the storage memory module  130  at any time.  
         [0034]     Basically, all the extendable peripherals can communicate with the back end  100  of the digital TV through the procedure described above. In addition to the front end  110 , the network service module  120 , and the storage memory module  130  mentioned before, any other extendable peripheral compliant with the standard defined in the disclosed extendable interface  200  for the digital TV can be implemented according to the invention.  
         [0035]     In fact, all the technical contents described before, including the extendable interface  200  and method for the digital TV, can be implemented on the so-called set top box. The operation mechanisms of the set top box and the digital TV are roughly the same. The only difference is that the digital TV has a display function while the set top box does not. Therefore, the implementation on the set top box is another embodiment of the invention.  
         [0036]     Certain variations would be apparent to those skilled in the art, which variations are considered within the spirit and scope of the claimed invention.
An extendable interface and method for digital televisions are disclosed. According to the pre-defined specifications of the interface, any extendable peripheral is appended to a back end of the digital television conveniently for extension. The extendable peripheral may comprise: a front end of the digital television, a network service module, a storage memory module and others compliant with the pre-defined specifications of the interface.