Abstract:
This invention is to provide a digital broadcast receiving apparatus which receives a digital broadcast, generates an analog video signal, and extracts content information from the received digital broadcast. The content information is multiplexed on the analog video signal as closed caption data and output.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-122886, filed Apr. 20, 2001, the entire contents of which are incorporated herein by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a digital broadcast receiving apparatus for receiving, e.g., digital television broadcast using a satellite and a control method therefor.  
           [0004]    2. Description of the Related Art  
           [0005]    As is known, digital television broadcast has been put into practice recently. In this digital television broadcast, program information is broadcast, and additionally, various kinds of content information are distributed by data broadcasting.  
           [0006]    Content information contain contents irrelevant to a program to be broadcast or contents related to a program to be broadcast (e.g., the program title, broadcast date, program information, and the like).  
           [0007]    A receiving apparatus for receiving such digital television broadcast can also display content information by OSD (On Screen Display) in decoding and displaying received program information.  
           [0008]    In a system for broadcasting both program information and its content information, how to process content information, i.e., digital data in converting received program information into an analog video signal and recording it on a tape by a VTR (Video Tape Recorder) or the like poses a problem.  
           [0009]    To solve this problem, in recent years, a standard called a video ID has been set as described in, e.g., “Technical Report of Electronic Industries Association of Japan, “Video ID Signal Transmission Scheme Using VBI (525P System)” enacted March, 1998”.  
           [0010]    In this video ID standard, digital information is arranged in the effective video portion of the 41st line of the VBI (Vertical Blanking Interval) of a luminance signal, thereby recording the information.  
           [0011]    This video ID standard has been initially set to transmit screen aspect ratio information along with the proliferation of wide screens with an aspect ratio of 16:9 and then revised for the other application purposes, i.e., to transmit various kinds of information such as the type of information to be transmitted and code assignment of information bits.  
           [0012]    The video ID standard surely allows to multiplex digital information on an analog video signal and record it, as analog information, on a recording medium such as a tape by a VTR.  
           [0013]    In the video ID standard, however, since digital information to be multiplexed on an analog video signal is data for a video index, the digital information cannot be played back and displayed unless a special player having a decoding function compatible with the video ID standard is used.  
         BRIEF SUMMARY OF THE INVENTION  
         [0014]    The present invention has been made in consideration of the above situation, and has as its object, to provide a digital broadcast receiving apparatus capable of easily playing back content information multiplexed on an analog video signal without using any device with a special function, and a control method therefor.  
           [0015]    According to the present invention, there is provided a digital broadcast receiving apparatus which receives a digital broadcast, generates an analog video signal, and extracts content information from the received digital broadcast, comprising a control section multiplexing the content information on the analog video signal as closed caption data, and outputting the content information.  
           [0016]    According to the present invention, there is also provided a control method for a digital broadcast receiving apparatus which receives a digital broadcast, generates an analog video signal, and extracts content information from the received digital broadcast, comprising the control step of multiplexing the content information on the analog video signal as closed caption data, and outputting the content information.  
           [0017]    According to the above arrangement and method, since content information is multiplexed on an analog video signal as closed caption data and output, the content information multiplexed on the analog video signal can easily be played back and displayed without using any device with a special function.  
           [0018]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0019]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0020]    [0020]FIG. 1 is a block diagram for explaining a digital STB according to the first embodiment of the present invention;  
         [0021]    [0021]FIG. 2 is a block diagram for explaining a digital STB according to the second embodiment of the present invention;  
         [0022]    [0022]FIG. 3 is a block diagram for explaining a digital STB according to the third embodiment of the present invention;  
         [0023]    [0023]FIG. 4 is a block diagram for explaining a digital television receiver according to the fourth embodiment of the present invention;  
         [0024]    [0024]FIG. 5 is a block diagram for explaining a digital STB according to the fifth embodiment of the present invention; and  
         [0025]    [0025]FIG. 6 is a block diagram for explaining a digital STB according to the sixth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    The first embodiment of the present invention will be described below in detail with reference to the accompanying drawing. FIG. 1 is a block diagram showing the schematic arrangement of a digital STB (Set Top Box)  11  to be described in the first embodiment.  
         [0027]    In this digital STB  11 , a tuner  12  extracts digital information of a desired channel from a received digital television broadcast wave and outputs the digital information to a digital information processing circuit  13  and content information extraction circuit  14 .  
         [0028]    The digital information processing circuit  13  extracts a video information component (also including an audio information component) from the received digital information, reconstructs the component into a digital video signal, and outputs the signal to an analog conversion processing circuit  15 .  
         [0029]    The analog conversion processing circuit  15  converts the received digital video signal into an analog video signal of NTSC (National Television System Committee) scheme and outputs the signal to a closed caption data insertion circuit  16 .  
         [0030]    The digital video signal generated by the digital information processing circuit  13  is guided to a digital video output terminal  17  and output from the digital STB  11  through a line  18  connected to the digital video output terminal  17 .  
         [0031]    The content information extraction circuit  14  extracts and reconstructs a content information component from the received digital information and outputs the component to the closed caption data insertion circuit  16 .  
         [0032]    The closed caption data insertion circuit  16  multiplexes, as closed caption data, the content information supplied from the content information extraction circuit  14  on a line  21  of the vertical blanking interval of the analog video signal supplied from the analog conversion processing circuit  15 .  
         [0033]    The analog video signal with the content information multiplexed by the closed caption data insertion circuit  16  is guided to an analog video output terminal  19  and output from the digital STB  11  through a line  20  connected to the analog video output terminal  19 .  
         [0034]    A monitor  21  and VTR  22  are connected to the line  20 . The analog video signal output to the line  20  is displayed on the screen of the monitor  21 .  
         [0035]    In this case, the content information multiplexed on the analog video signal can be decoded by a caption decoder  21   a  of the monitor  21  and displayed on the screen in synchronism with the video.  
         [0036]    The analog video signal output to the line  20  is also recorded on a magnetic tape  22   a  by the VTR  22  together with the content information multiplexed as closed caption data.  
         [0037]    Even in displaying on the monitor  21  the analog video signal played back from the magnetic tape  22   a  by the VTR  22 , the content information multiplexed on the analog video signal is decoded by the caption decoder  21   a  of the monitor  21  and displayed on the screen.  
         [0038]    According to the above-described first embodiment, the content information is multiplexed, as closed caption data, on the line  21  of the vertical blanking interval of the analog video signal.  
         [0039]    Hence, the content information can easily be played back and displayed using the caption decoder  21   a  of the VTR  22  without using any device with a special function.  
         [0040]    The monitor  21  normally has a function of automatically controlling the closed caption data display position on the screen not to overlap characters.  
         [0041]    For this reason, even when content information is multiplexed as closed caption data on an analog video signal that contains actual closed caption data to be used as a subtitle, the subtitle display is not adversely affected.  
         [0042]    [0042]FIG. 2 is a block diagram showing the second embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same parts in FIG. 2. A switch  23  that can be ON/OFF-controlled by a user is inserted between a content information extraction circuit  14  and a closed caption data insertion circuit  16 .  
         [0043]    When the switch  23  is turned on, content information output from the content information extraction circuit  14  can be guided to the closed caption data insertion circuit  16  and multiplexed on an analog video signal, as described above.  
         [0044]    On the other hand, when the switch  23  is turned off, the content information output from the content information extraction circuit  14  is not guided to the closed caption data insertion circuit  16  and not multiplexed on the analog video signal.  
         [0045]    That is, instead of always multiplexing the content information on the analog video signal, the user can select the state wherein the content information is to be multiplexed on the analog video signal or the state wherein the content information is not to be multiplexed on the analog video signal.  
         [0046]    [0046]FIG. 3 is a block diagram showing the third embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same parts in FIG. 3. A digital STB  11  incorporates an HDD (Hard Disk Drive)  24 .  
         [0047]    The HDD  24  can convert an analog video signal having content information multiplexed, which is output from a closed caption data insertion circuit  16 , into digital information and record it on a hard disk  24   a.    
         [0048]    When the digital STB  11  incorporates the HDD  24 , for example, a program that is being watched can be temporarily recorded, and later, stored on a tape or disk as needed. Multiple functions can be offered to a user.  
         [0049]    [0049]FIG. 4 is a block diagram showing the fourth embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same parts in FIG. 4. A monitor  25  having a caption decoder  25   a  is incorporated in the above-described digital STB  11 , thereby constructing a digital television receiver  26 .  
         [0050]    In this case, an analog video signal having content information multiplexed, which is output from a closed caption data insertion circuit  16 , is supplied to the monitor  25  so that the program and content information are displayed.  
         [0051]    As described above, the present invention can be applied not only to the digital STB  11  but also to the digital television receiver  26 . When the digital television receiver  26  is used, a monitor  21  need not be connected to a line  20  to which the analog video signal is output.  
         [0052]    [0052]FIG. 5 shows the fifth embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same parts in FIG. 5. A digital STB  11  incorporates a memory  27  which stores the ID (identify) of its own.  
         [0053]    A memory card  28  as a portable recording medium held by a user can be attached to the digital STB  11 . The memory card  28  stores ID information unique to the user who holds the card.  
         [0054]    A closed caption data insertion circuit  16  multiplexes, on an analog video signal, both or one of the ID information stored in the memory  27  and the ID information stored in the memory card  28  as closed caption data together with content information.  
         [0055]    According to the fifth embodiment, even when an analog video signal output from the digital STB  11  is illegally copied and put onto the market, the digital STB  11  used for the illegal copy or the user who is liable for the illegal copy can be specified by displaying the ID information multiplexed on the analog video signal as closed caption data.  
         [0056]    [0056]FIG. 6 shows the sixth embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same parts in FIG. 6. A closed caption data insertion circuit  16  multiplexes, on an analog video signal, both or one of ID information stored in a memory  27  and ID information stored in a memory card  28  as closed caption data. With this arrangement as well, the same effect as in the fifth embodiment can be obtained.  
         [0057]    A known technique related to a measure against illegal copy is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-358227. In this technique, an analog video signal is scrambled, and key information/authentication information and the like are exchanged between a sender and a receiver. This technique does not suggest the technique described in the fifth or sixth embodiment, i.e., multiplexing ID information on an analog video signal as closed caption data.  
         [0058]    The techniques described in the first to sixth embodiments can be arbitrarily selected and appropriately combined within the range without hindrance.  
         [0059]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.