Patent Publication Number: US-6987540-B2

Title: Digital broadcasting reception system, digital broadcasting receiver, display, printer and printing method

Description:
This is a continuation of Application No. 09/706,116, filed Nov. 3, 2000, now U.S. Pat. No. 6,870,571. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a digital broadcasting reception system comprising a receiver for receiving signals transmitted by digital broadcasting, a display for displaying the images and/or the sounds of the signals transmitted by digital broadcasting and received by the receiver and a printer for printing any of the images of the received signals. The present invention also relates to a digital broadcasting receiver comprising a printing section for printing any of the images of the signals transmitted by digital broadcasting and received by the receiver. Furthermore, the present invention also relates to a receiver for receiving signals transmitted by digital broadcasting and a printer adapted to print any of the images of the signals transmitted by digital broadcasting and received by the receiver. Finally, this invention also relates to a printing method to be used for printing images of signals transmitted by digital broadcasting by means of a printer according to the invention. 
     2. Related Background Art 
     Conventionally, an analog video printer is used for printing out any of the images of the reception signals displayed on a display, which may typically be a CRT (Cathode Ray Tube) display. 
       FIG. 1  of the accompanying drawings is a schematic block diagram of a known analog video printer. Referring to  FIG. 1 , analog video signals output from display  500  are input to the printer. In the case of  FIG. 1 , the display  500  is adapted to receive television signals and video signals and display images produced out of the received signal. An analog video printer  501  is adapted to receive analog video signals representing images displayed on the display  500 . 
     The analog video printer  501  performs an digitizing processing operation on the input analog video signal and stores it in frame memory  502  as video data to update the data already stored in the frame memory  502 . Upon receiving an external command for printing one or more than one images, the analog video printer  501  suspends the operation of storing data and updating the data in the frame memory  502  and reads out the video data stored in the frame memory  502  in order to print the images by means of printer engine  503 . 
     The analog video printer  501  is provided with a printing confirmation display section  504  which is typically a liquid crystal display for confirming the video data to be used for the printing and analogizes the stored and updated video data in frame memory  502  into an analog-video signal, which is then output to the printing confirmation display section  504 . The printing confirmation display section  504  displays the image generated from the input analog video signal. 
     An analog video printer  501  having a configuration as described is norm ally used to print a specific image contained in a continuous moving picture data. Therefore, the external printing command is a two step command including a first step of confirming the image selected out of the moving picture data and a second step of initiating the operation of printing the confirmed image. While the analog video printer  501  may not be provided with a printing confirmation display section  504 , then it is not possible to confirm in advance the image to be printed. 
     The above described analog video printer  501  is adapted to use generally available signals such as NTSC (National Television System Committee) signals, PAL (Phase Alternation by Line) signals, RGB video signals and S terminal video signals. 
     Analog multi-scan printers and PC printers normally are used for printing out images displayed on the displays of information processing apparatus such as personal computers (to be referred to as PCs hereinafter). 
     As shown in  FIG. 2  of the accompanying drawings, an analog multi-scan printer  510  is typically adapted to receive an analog CRT interface signal output from the PC main frame  511  to the display  512 . The analog multi-scan printer  510  duplicates the input analog CRT interface signal and outputs one of the signals to display  512 , while performs a processing operation of digitizing the other signal. The digitized signal is then sent to the frame memory  513  as video data to be recorded there in order to update the data already stored there. Then, upon receiving an external printing command input to it, it suspends the operation of storing data and updating the data in the frame memo  513  and reads out the video data stored in the frame memory  513  in order to print the images by means of printer engine  514 . 
     Alternatively, an analog multi-scan printer  510  may comprise a printing confirmation display section just like the above described analog video printer  501 . The analog CRT interface signal may be an RGB video signal and a synchronizing signal to be used for the RGB video signal. The signal mode of analog CRT interface signals is usually defined by the following values: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 horizontal resolution: 
                 640–1600 dots, 
               
               
                   
                 vertical resolution: 
                 480–1200 lines, 
               
               
                   
                 horizontal deflection frequency: 
                  30–107 kHz and 
               
               
                   
                 vertical deflection frequency: 
                  48–160 Hz. 
               
               
                   
                   
               
            
           
         
       
     
     An analog multi-scan printer  510  is adapted to operate for multi-scanning according to a signal of the above signal mode and obtain video data good for the size of the picture to be printed for the purpose of printing. 
       FIG. 3  of the accompanying drawings is a schematic broadcasting of a PC printer. Referring to  FIG. 3 , the PC printer  520  is adapted to receive printing data from PC main frame  521  apart from the video signal output from the PC main frame  521  to display  522  by way of general purpose printer interface. 
     With the PC printer  520 , character data and video data are generated by an application program driven by the PC main frame  521  and delivered to the OS (Operating System) of the PC main frame  521  to display images on the display  522 . Upon receiving a printing command, the OS causes the printer driver contained in the PC main frame  521  to start operating and then the printer driver converts the character data and the video data into printing data in a format adapted to the PC printer  520  connected to the PC main frame  521  and transmits the printing data to the PC printer  520 . Then, the PC printer  520  translates the printing data it receives and operates to print out appropriate images as it is driven to operate by printer engine  523 . 
     The general purpose printer interface of the PC printer  520  may typically be a Bi-Centronics (IEEE-1284), an RS-232C, an SCSI, an Ir-DA or a USB. 
     When receiving news and programs of television broadcasting, conventionally, analog television signals are received by means of a receiver. The received analog television signal is then processed by an analog electronic circuit to obtain the image represented by the signal, which image is then displayed on a display. However, television broadcasting is expected to replace analog signals with digital signals in near future. 
     More specifically, in Japan, CS digital broadcasting started in October &#39;96 and it is expected that the current CATV, BS broadcasting and ground wave broadcasting are digitized very soon. Digital television broadcasting can provide higher quality images than analog television broadcasting. Furthermore, digital television broadcasting can additionally provide various information services referred to as SI (Service Information) in addition to the transmission of ordinary television signals. Services such as EPGs (Electronic Program Guides) can be provided by means of SI signals and displayed on displays. 
     Thus, with digital television broadcasting, it is possible to display not only news and programs but also various program guides simultaneously or selectively. Then, the television display set is required to display high definition images in terms of not only pictures but also characters. Additionally, the receiver set is required to process various digital signals it receives and send the processed digital signals to the display set. 
     Meanwhile, in recent years, various organizations have been studying about digital interface standards to be established for displays that are adapted to be connected to the video ports of various electronic devices such as personal computers and set top boxes (to be referred to as STB hereinafter). For instance, the Japan Electronic Industry Development Association (JEIDA) has already established the Digital Interface Standards for Monitor, Version 1.0 in January &#39;99. 
     Under these circumstances, conventional analog video printers  501 , analog multi-scan printers  510  and PC printers  520  as described above give rise to a number of problems particularly in terms of printing quality, printing rate and the cost of printer when they are used for printing pictures and service information provided by digital television broadcasting. 
     More specifically, the analog video printer has to use analog video signals  501  such as NTSC signals. The number of dots that an analog video signal can provides for an image is 600 dots×450 dots at most. Additionally, analog video signals faces a limit in terms of high definition when providing color information for moving images, although this may not be any problem for viewers seeing them on the television screen because of the perceptual characteristics of the visual sense of man. Still additionally, analog video signals are limited in terms of the length of the signal line that can be used for sending them from the display to the printer. In other words, it is difficult to arrange the display and the printer remotely relative to each other. 
     On the other hand, the analog multi-scan printer can obtain video information up to 1600 dots×1200 dots per image depending on the signal mode to be used. However, on characteristics of the analog CRT interface signal, the analog video printer  501  also faces a limit in terms of the length of the signal line that can be used for sending video signals from the display to the printer. Additionally, the analog multi-scan printer  510  requires circuits for A/D conversion and D/A conversion along with measures for preventing noises and degradation of signals, which make the printer very complex and costly. 
     The PC printer  520  can transmit video data almost without limitations in terms of resolution and quality of printed images because the general purpose printer interface can cope with high speed operations. However, most of the operation of processing images necessary for the printer engine  523  of the PC printer  520  for printing has to be carried out by the PC main frame  521 . Then, the RAM and the hard disk memory of the PC main frame  521  are required to have a large memory capacity in order to make themselves adapted to high resolution and high quality printing. Additionally, the PC main frame  521  has to be provided with a CPU that can operates at high speed in order to process video data at a rate corresponding to the resolution and the quality of the images to be printed Still additionally, the PC main frame  521  has to be provided with an operational environment good for such high speed operations. 
     Finally, when transmitting video data by connecting a television receiving set for receiving television broadcasting and a printer and using a general purpose printer interface such as the one used for the above described PC printer  520 , the television receiving set has to be provided with a high speed arithmetic processing capacity, a large capacity memory means and a high speed output port for the general purpose interface to push up the cost of the television receiving set, although the high speed arithmetic processing capacity, the large capacity memory means and the high speed output port for the general purpose interface remain useless unless a printer is connected to the television receiving set. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the above described problems, it is therefore the object of the present invention to provide a digital broadcasting reception system, a digital broadcasting receiver, a receiver, a printer and a printing method that does not require any high speed transmission of video data when printing images contained in the digital broadcasting nor costly circuits and features that are useless except for printing. 
     According to the invention, the above problem is dissolved by providing a digital broadcasting reception system comprising a receiver for receiving digital broadcasting, a display for displaying the images of the digital broadcasting received by said receiver and a printer for printing images contained in the digital broadcasting received by said receiver;
         said receiver, said display and said printer being connected to each other by way of a first signal transmission means for transmitting digital signals;   said receiver having:   a reception means for receiving digital broadcasting;   an imaging means for generating video data by performing a predetermined imaging operation according to the received signals of digital broadcasting; and   an output means for transmitting the video data generated by said imaging means by way of said first signal transmission means;   said printer having:   a reception means for receiving video data transmitted by said first signal transmission means; and   a printing means for printing the images of the video data received by said reception means.       

     With a digital broadcasting reception system according to the invention and having the above described configuration, the video data to be used for printing can be transmitted at high speed because the first signal transmission means that is provided to transmit video data from the receiver to the display is used when the printer receives the video data from the receiver. Additionally, it is no longer necessary for the system to comprise a D/A converter circuit nor an A/D converter circuit because the video data contained in the digital broadcasting are transmitted by the first signal transmission means for transmitting digital signals so that noises and any degradation of signals can be prevented from taking place and the operation of printing high quality images can be conducted at low cost. 
     In another aspect of the present invention, there is also provided a a digital broadcasting receiver comprising a receiving section for receiving digital broadcasting and a printing section connected to said receiving section by way of a first signal transmission means for transmitting signals in order to print images contained in the digital broadcasting received by said receiving section;
         said receiving section having:   a reception means for receiving digital broadcasting;   an imaging means for generating video data by performing a predetermined imaging operation according to the received signals of digital broadcasting; and   an output means for transmitting the video data generated by said imaging means by way of said first signal transmission means;   said printing section having:   a reception means for receiving video data transmitted by said first signal transmission means; and   a printing means for printing the images of the video data received by said reception means.       

     With a digital broadcasting receiver according to the invention and having the above described configuration, the video data to be used for printing can be transmitted at high speed because the first signal transmission means that is provided to transmit video data from the receiving section to an external display is used when the printing section receives the video data from the receiving section. Additionally, it is no longer necessary for the system to comprise a D/A converter circuit nor an A/D converter circuit because the video data contained in the digital broadcasting are transmitted by the first signal transmission means for transmitting digital signals so that noises and any degradation of signals can be prevented from taking place and the operation of printing high quality images can be conducted at low cost. 
     In still another aspect of the present invention, there is provided a receiver comprising:
         a reception means for receiving digital broadcasting;   an imaging means for generating video data by performing a predetermined imaging operation according to the received signals of digital broadcasting; and   an output means for transmitting the video data generated by said imaging means to a display for displaying digital broadcasting and a printer for printing images contained in digital broadcasting by way of a first signal transmission means.       

     With a receiver according to the invention and having the above described configuration, the video data to be used for printing can be transmitted at high speed because the first signal transmission means that is provided to transmit video data to the display is used when the printer receives the video data. Additionally, it is no longer necessary for the system to comprise a D/A converter circuit nor an A/D converter circuit because the video data contained in the digital broadcasting are transmitted by the first signal transmission means for transmitting digital signals so that noises and any degradation of signals can be prevented from taking place and the operation of printing high quality images can be conducted at low cost. 
     In still another aspect of the invention, there is provided a printer for printing the images of the video data generated by a receiver out of the digital broadcasting received by it, said printer comprising:
         a reception means for receiving the video data transmitted from said receiver to a display for displaying digital broadcasting and to the printer by way of a first signal transmission means for transmitting signals; and   a printing means for printing the images of the video data received by said reception means.       

     With a printer according to the invention and having the above described configuration, the video data to be used for printing can be transmitted at high speed because the first signal transmission means that is provided to transmit video data from the receiver to the display is used when the printer receives the video data. Additionally, it is no longer necessary for the system to comprise a D/A converter circuit nor an A/D converter circuit because the video data contained in the digital broadcasting are transmitted by the first signal transmission means for transmitting digital signals so that noises and any degradation of signals can be prevented from taking place and the operation of printing high quality images can be conducted at low cost. 
     In a further aspect of the present invention, there is also provided a printing method for receiving digital broadcasting by means of a receiver and printing images contained in the digital broadcasting received by said receiver, said method comprising:
         connecting said receiver, a display for displaying the images of the digital broadcasting received by said receiver and said printer to each other by means of a first signal transmission means for transmitting digital signals;   said receiver operating for:   receiving digital broadcasting;   generating video data by performing a predetermined imaging operation according to the received signals of digital broadcasting; and   transmitting the video data generated by said imaging means by way of said first signal transmission means;   said printer operating for:   receiving the video data transmitted by said first signal transmission means; and   printing the images of the video data received by said reception means.       

     With a printing method according to the invention and adapted to operate with the above described steps, the video data to be used for printing can be transmitted at high speed because the first signal transmission means that is provided to transmit video data from the receiver to the display is used when the printer receives the video data from the receiver. Additionally, it is no longer necessary for the system to comprise a D/A converter circuit nor an A/D converter circuit because the video data contained in the digital broadcasting are transmitted by the first signal transmission means for transmitting digital signals so that noises and any degradation of signals can be prevented from taking place and the operation of printing high quality images can be conducted at low cost. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       In the accompanying drawing: 
         FIG. 1  is a schematic block diagram of a known analog video printer, illustrating a mode of operation thereof; 
         FIG. 2  is a schematic block diagram of a known multi-scan printer, illustrating a mode of operation thereof, 
         FIG. 3  is a schematic block diagram of a known PC printer, illustrating a mode of operation thereof, 
         FIG. 4  is a schematic block diagram of a digital television receiver according to the invention; 
         FIG. 5  is a schematic block diagram of a digital television receiver and a printer according to the invention; 
         FIG. 6  is a schematic block diagram of an STB, a display and a printer according to the invention; 
         FIG. 7  is a schematic block diagram of an STB and a display according to the invention; 
         FIG. 8  is a schematic block diagram of an STB according to the invention; 
         FIG. 9  is a schematic block diagram of a display according to the invention; 
         FIG. 10  is a schematic illustration of an initial image display on a display according to the invention; 
         FIG. 11  is a schematic illustration of navigation that can be displayed on the screen of a display according to the invention; 
         FIG. 12  is a schematic block diagram of a printer according to the invention; 
         FIG. 13  is a schematic block diagram of a printing output processing section that can be used for a printer according to the invention; 
         FIG. 14  is a schematic illustration of a processing operation of the enlarging section of a printer according to the invention; 
         FIG. 15  is a schematic block diagram of another printing output processing section that can also be sued for a printer according to the invention; 
         FIG. 16  is a schematic block diagram of a printing head that can be used or a printer according to the invention; 
         FIG. 17  is a flow chart of an operation of an STB, a display and a printer according to the invention; 
         FIG. 18  is a flow chart of another operation of an STB, a display and a printer according to the invention; 
         FIG. 19  is a flow chart of still another operation of an STB, a display and a printer according to the invention; 
         FIG. 20  is a schematic block diagram of another printer according to the invention; 
         FIG. 21  is a schematic block diagram of another STB according to the invention; 
         FIG. 22  is a schematic block diagram of another printer according to the invention; 
         FIG. 23  is a schematic block diagram of still another STB according to the invention; 
         FIG. 24  is a schematic block diagram of still another printer according to the invention; and 
         FIG. 25  is a schematic block diagram of still another printer according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Now, the present invention will be described in greater detail by referring to the accompanying drawings that illustrate preferred embodiments of the invention. While a digital broadcasting reception system according to the invention comprises a receiving section for receiving digital broadcasting, a display section for display images of digital broadcasting and a printing section for printing images contained in digital broadcasting, each these sections can be configured in various different ways. Thus, the embodiments as described below differ from each other in terms of the configuration of any of these sections. 
     In the following description, the expression of “digital broadcasting” refers broadcasting transmitted from a broadcasting station in the form of digital signals. As far as this patent application is concerned, digital broadcasting is not limited to a specific mode of transmission and includes conventional ground wave broadcasting, satellite broadcasting for transmitting signals by way of an artificial satellite such as BS broadcasting and CS broadcasting and wired broadcasting for transmitting signals by way of cables and/or wires such as CATV. 
     The present invention can be applied to a digital television receiving set  10  as shown in  FIG. 4 . The digital television receiving set  10  comprises a receiving section  11  for receiving digital broadcasting, a display section  12  for displaying digital broadcasting and a printing section  13  for printing images contained in digital broadcasting. 
     The present invention can also be applied to a digital television receiving set  20  and a printer  21  connected to the digital television receiving set  20  as shown in  FIG. 5 . The digital television receiving set  20  comprises a receiving section  22  for receiving digital broadcasting and a display section  23  for displaying digital broadcasting as integral parts thereof. In other words, the digital television receiving set  20  of  FIG. 5  can be obtained by separating the printing section  13  of the digital television receiving set  10  of  FIG. 4  and arranging it externally. 
     The present invention can also be applied to a set top box (to be referred to as STB hereinafter)  30  and a display  31  and a printer  32  connected to the STB  30  as shown in  FIG. 6 . The STB  30  has the function of receiving digital broadcasting. In other words, the STB  30 , the display  31  and the printer  32  of  FIG. 6  can be obtained by separating the receiving section  11 , the display section  12  and the printing section  13  of the digital television receiving set  10  of  FIG. 4  and arranging them independently. 
     The present invention can also be applied to a set top box (STB)  40  and a display  41  connected to the STB  40  as shown in  FIG. 7 . The STB  40  comprises a receiving section  42  for receiving digital broadcasting and a printing section  43  for printing images contained in digital broadcasting. In other words, the STB  40  of  FIG. 7  can be obtained by combining the STB  30  and the printer  32  of  FIG. 6  into an integral unit. 
     As pointed out above, the present invention can be applied to an arrangement obtained by combining a receiving section for receiving digital broadcasting, a display section for display digital broadcasting and a printing section for printing images contained in digital broadcasting, which may be configured in many different ways. According to the present invention, a first signal transmission means for transmitting digital signals of video data contained in the digital broadcasting received by the receiving section from it to the display section is also utilized when transmitting video data contained in the digital broadcasting to the printing section. 
     In other words, the present invention is characterized by utilizing a first signal transmission means adapted to transmit digital signals of video data at relatively high speed from the receiving section to the display section also for the printing section to obtain video data from the receiving section. As a result, according to the invention, it is possible to transmit video data to be used by the printing section for printing at high speed from the receiving section. Additionally, since the video data contained in the received digital broadcasting are transmitted by way of the first signal transmission means adapted to transmit digital signals, it is no longer necessary to arrange a D/A converter circuit and an A/D converter circuit in order to transmit video data from the receiving section to the printing section so that noises and any degradation of signals can be prevented from taking place and the operation of printing high quality images can be conducted at low cost. 
     For the purpose of the present invention, the first signal transmission means may be wired type signal transmission means typically comprising wires and/or optical fibers or wireless type signal transmission means adapted to transmit signals by way of radio waves and/or infrared rays. 
     As described above, according to the invention, a receiving section, a display section and a printing section can be combined in various different ways. Therefore, the present invention will be firstly described in detail by referring to  FIG. 6  illustrating a first embodiment of the invention where an STB  30 , a display  31  and a printer  32  are arranged separately. 
     Embodiment 1 
     Referring to  FIG. 8 , an STB  30  typically comprises a down converter  50 , a tuner  51 , a digital demodulator  52 , an error correcting section  53 , a descrambling section  54 , a packet isolator  55 , a video decoder  56 , an audio decoder  57 , a data decoder  58 , a synthesizer  59 , a video RAM  60 , a digital video signal output section  61  and a monitor control signal output section  62 . The STB  30  additionally comprises an I/O control section  63 , a modem  64 , a CPU system  65  and a printer control signal interface  66 . Note that, in  FIG. 8 , the arrows indicate the flows of different signals that are exchanged among the components of the STB  30 . 
     While the STB  30  may be so configured as to be adapted to receive digital broadcasting in various different modes including ground wave broadcasting, satellite broadcasting and wired broadcasting, it will be described below in terms of a so-called IRD (Integrated Receiver Decoder) that is adapted to receive currently available CS digital broadcasting. In the case of CS digital broadcasting, digital signals including those of moving image information, still image information and SI (Service Information) are provided by broadcasting stations and so-called service providers and contents providers. SI refers to signals representing tables describing various service information arranged in a predetermined transmission format. The transmission service station transmits digital signals by way of ground wave broadcasting, satellite broadcasting or wired broadcasting. If, necessary, digital signals may be scrambled so that receivers who have not concluded an agreement with the transmission service station cannot properly receive digital broadcasting. 
     The down converter  50  is connected to a reception antenna, which is, for example, assigned to the 12 GHz band and converts the received radio wave into a wave with an intermediate frequency approximately between 950 MHz and 2 GHz. Note that, however, the down converter  50  of the STB  30  is not limited to such that is connected to an antenna of the above described type but may alternatively be connected to an antenna for receiving ground wave broadcasting, one for receiving satellite broadcasting or a signal line for wired broadcasting. 
     The tuner  51  tunes in specific signals of the digital broadcasting coming from the down converter  50  to show an intermediate frequency. In other words, it select the signals of a specific channel out of the digital broadcasting signals coming from the down converter  50 . As will be described hereinafter, it may be so arranged that the tuner  51  can select a specific channel according to the command issued by the user by way of a remote control unit. 
     The digital demodulator  52  performs a demodulating operation of QPSK (Quadrature Phase Shift Keying) on the digital broadcasting signals selected by the tuner  51 . For example, the digital demodulator  52  may be adapted to have a band width of 27 MHz and transmit its output bit stream at a rate of 42.192 Mbit/s. 
     The error correcting section  53  performs an operation of Viterbi decoding, synchronous detection, Reed-Solomon decoding ( 204 ,  188 ) and deinterleaving on the digital broadcasting signals QPSK-demodulated by the digital demodulator  52  and extract, for example, a 29.162 Mbit/s transport stream (TS). The error correcting section  53  may typically show a convolution rate between ½ to ⅞ when carrying out the operation of Viterbi decoding. 
     The descrambling section  54  performs a processing operation of descrambling the packet having a specific PID (Packet ID) in the transport stream extracted by the error correcting section  53 . For instance, MULTI2 for classifying signals by means of block codes may be used for the scrambling algorithm. It may alternatively be so arranged that the STB  30  externally takes out the descrambled signals by outputting them from an output terminal at high speed. 
     The packet isolator  55  operates to take out only the packet of a desired program from the signals descrambled by the descrambling section  54 . The signals produced by the descramblinging section  54  are those containing video information and audio information that are multiplexed typically according to the MPEG2 Standards. Thus, the packet isolator  55  takes out only the packet of a desired program from the multiplexed signals while it obtains the SI information and regenerates the clock at the same time. Then, the packet isolator  55  outputs the packet it takes out to the video decoder  56 , the audio decoder  57  and the data decoder  58 . 
     Thus, the STB  30  has the down converter  50 , the tuner  51 , the digital demodulator  52 , the error correcting section  53 , the descrambling section  54  and the packet isolator  55  collectively as reception means for receiving digital broadcasting. It may be needless to say, however, that the configuration of the reception means of the STB  30  is not limited to the above described one and the reception means of the STB  30  may have any other configuration so long as it is adapted to properly receive digital broadcasting. 
     The video decoder  56  and the audio decoder  57  decodes respectively the video data and the audio data that are coded typically according to the MPEG2 Standards and taken out from the packet sent from the packet isolator  55 . Then, the video decoder  56  outputs the decoded video data to the synthesizer  59 , while the audio decoder  57  externally outputs the decoded audio data as audio signal. 
     The data decoder  58 , on the other hand decodes the SI information obtained by the packet isolator  55  that may include EPG (Electronic Program Guide) information and detailed program information as well as other pieces of information. After the decoding, it outputs the part of the SI information that can be directly developed into displayable data to the synthesizer  59  and the remaining part of the SI information that cannot be directly developed into displayable data to the CPU system  65  by ways the system bus as SI control signal. The SI control signal output to the CPU system  65  is processed by the latter before it is output the synthesizer  59  as SI display signal. At this time, the CPU system  65  converts the data of the SI information that cannot be directly developed into displayable data into a displayable SI display signal typically by way of a converting operation utilizing font data stored in a font ROM. 
     The synthesizer  59  synthetically combines the video data decoded by the video decoder  56 , the SI information decoded by the data decoder  58  and the SI display signal input from the CPU system  65  and prepare a display data of a frame to be displayed on the display  31 . 
     Thus, according to the invention, the STB  30  has the video decoder  56 , the audio decoder  57 , the data decoder  58 , the synthesizer  59  and the video RAM  60  collectively as imaging means. It may be needless to say, however, that the configuration of the imaging means of the STB  30  is not limited to the above described one and the imaging means of the STB  30  may have any other configuration so long as it is adapted to properly generate video data by carrying out a predetermined imaging processing operation according to the received digital signal. 
     The digital video signal output section  61  outputs the display data prepared by the synthesizer  59  to the outside as digital signal. 
     The monitor control signal output section  62  externally outputs the monitor control signal sent from the CPU system  65  by way of the system bus as digital signal. 
     Thus, the STB  30  has the digital video signal output section  61  and the monitor control signal output section  62  collectively as digital video interface for transmitting digital signals to the external display  31  that is connected to it. While the digital video signal output section  61  and the monitor control signal output section  62  are shown separately in  FIG. 8 , it may alternatively be put together to form an integral component of the STB  30  so long as they operate properly as digital video interface. 
     While digital signals output from the STB  30  are not limited to the signal format adapted to the digital video signal output section  61  and the monitor control signal output section  62 , they preferably conform to given signal format standards because the STB  30  can be connected to a display  31  and/or a printer  32  conforming to the same standards without problem. 
     An example of signal format standards is the Digital Interface Standards for Monitor Version 1.0 established by the Japan Electronic Industry Development Association (JEIDA) in January, 1999. The above standards support the following signal formats.
     1) digital data
       TMDS (Transition Minimized Differential Signalling)   LVDS (Low Voltage Differential Signalling)   GVIF (Giga-bit Video Interface)   Conforming to any of the above is indispensable.   
       2) isolated horizontal and vertical synchronizing signals indispensable   3) data enable signal indispensable   4) DDC (Digital Data Channel) indispensable   5) signal for VESA hot plug (SENS) indispensable   6) USB (Universal Serial Bus) optional   

     Then, four standards are defined as shown in Table I below by combining the above signal formats. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 data 
                 support 
                 interface terminal 
               
            
           
           
               
               
               
               
               
            
               
                   
                 format 
                 signal 
                 receiver side 
                 display side 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 standard 
                 TMDS 
                 digital data, 
                 MDR connector 
                 MDR connector 
               
               
                 1 
                   
                 DDC, USB 
                 26, 20 pins &amp; 
                 26 pins &amp; 
               
               
                   
                   
                   
                 compatible ones 
                 compatible ones 
               
               
                 standard 
                 LVDS 
                 digital data, 
                 MDR connector 
                 MDR connector 
               
               
                 2a 
                   
                 DDC, USB 
                 26 pins &amp; 
                 26 pins &amp; 
               
               
                   
                   
                   
                 compatible ones 
                 compatible ones 
               
               
                 standard 
                 LDI 
                 digital data, 
                 MDR connector 
                 MDR connector 
               
               
                 2b 
                   
                 DDC, USB 
                 36 pins &amp; 
                 36 pins &amp; 
               
               
                   
                   
                   
                 compatible ones 
                 compatible ones 
               
               
                 standard 
                 GVIF 
                 digital data, 
                 MDR connector 
                 MDR connector 
               
               
                 3 
                   
                 DDC, USB 
                 14 pins &amp; 
                 14 pins &amp; 
               
               
                   
                   
                   
                 compatible ones 
                 compatible ones 
               
               
                   
               
               
                 *LDI stands for LVDS Display Interface. 
               
            
           
         
       
     
     Of the four standards shown in Table 1 above, Standard 2b and Standard 3 are those for transmitting both video signals and control signals by way of a same signal line. If the STB  30  is made to conform to Standard 2b and Standard 3, it is desirable to put the digital video signal output section  61  and the monitor control signal output section  62  together into a single and integral component in a manner as described above so as to transmit both video signals and control signals by way of a same signal line. 
     As pointed out above, the STB  30  has the digital video signal output section  61  and the monitor control signal output section  62  as output means for sending the video data generated by the imaging means to the display  31  and the printer  32 . However, the configuration of the output means of the STB  30  is not limited to the above described one and may be modified appropriately so long as the output means is adapted to transmit the video data generated by the imaging means by way of the first signal transmission means. 
     Of the STB  30 , the I/O control section  63  is connected to the system bus arranged within the STB  30  and typically adapted to receive various commands issued by the user by way of a remote control unit to operate the STB  30 . The I/O control section  63  may be so arranged as to record data on and reproduce data from an IC card. More specifically, for instance, when receiving scrambled digital broadcasting, such an IC card may be used to store information on the subscription status of the user for receiving digital broadcasting from pay TV stations including data on the payment of subscription fees so that the STB  30  may descramble only the digital broadcasting signals for which the user is eligible and control the remaining reception time of the user. Additionally, the I/O control section  63  may be so arranged as to retrieve subscription-related information from digital broadcasting stations and decode E-mails it receives by way of the modem  64 . 
     The modem  64  is adapted to transmit and receive various information by way of telecommunication networks such as telephone lines and internet and connected to the system bus arranged within the STB  30 . While the STB  30  does not necessarily comprise a modem  64 , it can carry out the following processing operations when it is provided with a modem  64 . 
     For example, the modem  64  may be used to transmit subscription-related information to and receive such information from (up link/down link) the subscriber management centers of digital broadcasting stations by way of telecommunication networks in connection with the operation of recording and reproducing such information by means of an IC card. If, on the other hand, the SI information output from the data decoder  58  contains a command for obtaining certain information by accessing a given address by way of a telecommunication network, the modem  64  may be used to obtain such information. If necessary, the obtained information may then be processed for development by means of the CPU system  65  to generate SI display signal. 
     The CPU system  65  typically comprises a CPU (Central Processing Unit), a program ROM (Read Only Memory), a font ROM, a RAM (Random Access Memory) and a flash memory. The CPU system  65  is connected to the system bus arranged within the STB  30  and adapted to control the various components of the STB  30  by transmitting and receiving control signals by way of the system bus. More specifically, the CPU system  65  controls the various components of the STB  30  according to the operating commands input to the I/O control section  63  by the user. Note that, in  FIG. 8 , the arrows showing the flows of various control signals being exchanged between the system bus and the components of the STB  30  are partly omitted. 
     As pointed out above, the CPU system  65  converts the data of the SI information that cannot be directly developed into displayable data into a displayable SI display signal typically by way of a converting operation utilizing font data stored in a font ROM according to the SI control signal output from the data decoder  58 . As a result, it is possible to realize an OSD (On Screen Display) of character information according to the SI information fed to it. 
     The printer control signal interface  66  is connected to the system bus arranged within the STB  30  and operates to exchange printer control information with the printer  32 . A printer control signal is a signal to be sent from the STB  30  to the externally connected printer  32  to order the start and/or the suspension of a printing operation or specify the size and the contents of each image to be printed by the printer. A printer control signal is also used by the printer  32  to provide the STB  30  with information on the completion of a printing operation, an out-of-printing paper status, a jammed sheet status or an out-of-ink status. 
     For example, upon receiving a printing start command input to the I/O control section  63  by the user and transmitted to it by way of the system bus, the printer control signal interface  66  transmits a printer control signal for starting a printing operation to the printer  32 . Then, when the printer  32  properly completes the printing operation, it receives the information transmitted from the printer  32  on the completion of the printing operation to recognize that the printing operation is properly completed. 
     If, on the other hand, the printer  32  can not properly carry out the printing operation due to an out-of-printing paper status or a jammed sheet status, the printer control signal interface  66  receives the information telling about the uncompleted printing operation to recognize that the printer operation is not completed properly. It may be so arranged that the STB  30  generates an SI control signal indicating the uncompleted printing operation by means of the CPU system  65  and transmits a predetermined corresponding video signal to the display by way of the synthesizer  59  and the digital video signal output section  61  so that an image indicating the uncompleted printing operation is displayed on the display  31 . 
     Meanwhile, in this embodiment, the STB  30  and the printer  32  are connected to each other not only by the above described first signal transmission means but also by a second signal transmission means showing a transmission rate lower than the first signal transmission means. Then, the printer control signal interface  66  of the STB  30  is adapted to exchange printer control signals with the printer  32  by way of the second signal transmission means. However, the present invention is by no means limited to the above configuration and it may be so arranged that the printer control signal may be inserted into the gaps of the video signal transmitted from the STB  30 . With this arrangement, then the STB  30  and the printer  32  exchange control signals by way of the first signal transmission means. 
     It should be noted that a printer control signal contains by far less information than the video data to be transmitted by way of the first signal transmission means at a time so that it is not necessary for the STB  30  and the printer  32  to exchange printer control signals by way of the first signal transmission means that is adapted to transmit data at a high rate. Therefore, the first signal transmission means may be dedicated to the transmission of video data by using the separate second signal transmission means for the exchange of printer control signals between the STB  30  and the printer  32 . Then, the first signal transmission means is prevented from reducing its signal transmission rate due to printing control signals that may otherwise sneaks in there. 
     As will be described hereinafter by referring to other embodiments of the present invention, it may be so arranged that the second signal transmission means is used not only for transmitting printing control signals but also various other signals that contain by far less information than the video data to be transmitted by way of the first signal transmission means. 
     For the purpose of the present invention, the second signal transmission means may be a wired type signal transmission means connecting wires or optical fibers or a wireless type signal transmission means of transmitting signals by way of radio waves and/or infrared rays. More specifically, it may be a signal transmission means conforming to appropriate known standards such as IEEE 802.3 (Ethernet), IEEE 1394 or USB. 
     As shown in  FIG. 9 , the display  31  typically comprises a digital video signal input section  70 , a monitor control signal input section  71 , a display device drive section  72 , a display device  73  and a loudspeaker  74 . In  FIG. 9 , the arrows show the flows of various signals being exchanged among the various components of the display  31 . 
     The digital video signal input section  70  and the monitor control signal input section  71  receives the respective video signals, which are a digital video signal and a monitor control signal, transmitted from the STB  30  and extract the video data to be displayed on the display  31  out of the video signals. 
     The display device drive section  72  receives the video data extracted by the digital video signal input section  70  and the monitor control signal input section  71  and generates a drive signal for driving the display device  73  on the basis of the video data. The drive signal typically comprises RGB signals. 
     The display device  73  operates to display a given image according to the drive signal generated by the display device drive section  72 . For example, it may be a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display) or a plasma display. 
     The loudspeaker  74  receives the audio signal transmitted from the STB  30  and reproduce the original sound represented by the audio signal. 
     Now, an example of image that can be displayed on the display device  73  of the display  31  will be discussed below. As pointed out above, the present invention is adapted to receive not only digital broadcasting transmitted in the form of ground wave broadcasting, satellite broadcasting or wired broadcasting and aimed at ordinary homes but also conventional analog broadcasting and various other services provided in an internet environment by means of a comprehensive information terminal. For a comprehensive information terminal, it is important that it be used easily to accurately select a desired program for the purpose of viewing out of a large number of programs it receives and, at the same time, it is easy to operate it when selecting a particular service out of a number of services provided to it. 
       FIG. 10  schematically illustrates a preferred image that is displayed on the display device  73  of the display  31  to allow an easy selecting operation to the viewer. Note that the image as shown in  FIG. 10  is an example of initial image that is displayed on the display device  73  immediately after the display  31  is activated. Thus, as shown in  FIG. 10 , the initial image of the display  31  may comprise an area S 1  for showing the high definition television program that is currently being received, an area S 2  for showing a list of the programs that are currently being received, an area S 3  for showing a list of the programs that are stored in the home server, an area S 4  for showing information on the weather, an area S 5  for showing a table of various broadcast programs and an area S 6  for showing character information such as headlines of television newspapers. 
     The initial image of the display  31  may further comprise an area S 7  to be used for selecting a sound service out of a number of sound services including news broadcasting services and music broadcasting services, an area S 8  to be used for selecting and acting on an internet-related service such as E-mail and an area S 9  to be used for issuing a command for a printing operation to the printer  32 . 
     The component images of the above areas for synoptically showing the various services are synthetically combined by the synthesizer  59  of the STB  30  and displayed on the display device  73  of the display  31 . Thus, the user can select a specific service from the displayed images by means of a remote control unit and the I/O control section  63 . Upon receiving the command from the user, the STB  30  enlarges and displays the image of the selected service, which may be a television program, a music program or some other service. 
     It may alternatively be so arranged that an initial image as shown in  FIG. 10  is displayed for a predetermined period of time after the activation of the display  31  and, if the user does not issue any command during the period, a preselected specific service, which may be a television program, a music program or some other service, is shown on the display device  73 . The arrangement of the component images of the television programs, the music programs and other services may be customized to meet the request of the user. 
     A navigating operation using the initial image of  FIG. 10  that is displayed on the display  31  will be described below. In  FIG. 10 , the arrows indicate how the image shown on the display  31  changes depending on the command issued by the user. 
     Referring now to  FIG. 11 , the display  31  is in state S 10  of showing the initial image. If the user issues a command for displaying the weather forecast, the display  31  moves from state S 10  to state S 11  where the weather forecast is displayed on the entire display device  73 . The display  31  may move back from state S 11  to state S 10  of showing the initial image if a command is issued by the user for such a move. 
     If, on the other hand, the user issues a command for displaying the table of broadcast programs to the display  31  showing the initial image, the display  31  moves from state S 10  to state S 12  where the table of broadcast programs is enlarged and displayed on the entire display device  73 . 
     The state S 12 , if the user issues a command for displaying detailed information on the programs shown on the table, the STB  30  accesses the sources of the programs typically by means of a modem  64  and a telecommunication network to obtain detailed information on the programs and moves to state SI  3  where the obtained information is displayed on the display device  73 . 
     If, on the other hand, the user issues in state S 10  of showing the initial image or in state S 12  of showing the program table a command for selecting a specific broadcast program, in state S 14  enlarges the selected broadcast program and displays it on the display device  73 . 
     In state S 12  where the table of broadcast programs is shown on the entire display device  73 , the user may issue a command to make the STB  30  move to state S 15  where the user can preset the STB  30  for recording a specific program: Additionally, it can be so arranged that the STB  30  moves from state S 15  to state S 14  at the preset time where the selected specific program is displayed on the entire display device  73 . 
     Referring also to  FIG. 11 , if the user issues a certain command in state S 14  where a specific program is displayed on the entire display device  73 , the STB  30  moves to state S 16  where a list of data relating to the broadcast program that is being displayed is displayed on the display device  73  so that the user may select any specific data item. Then, the STB  30  moves to state S 17  where the selected data item is displayed on the display device  73 . The STB  30  can obtain such information by accessing the source of the program typically by means of a modem  64  and a telecommunication network. 
     If, on the other hand, the user issues a certain command in state S 10  of showing the initial image, the STB  30  may move to state S 18  where the headlines of certain television newspapers are shown. If the user select a specific article in state S 18 , the STB  30  moves to state S 19  where the full text of the selected article is displayed. Again, the STB  30  can obtain the full text of the selected article by accessing the news source typically by means of a modem  64  and a telecommunication network. Alternatively, the user may so operates the STB  30  that the latter moves from state S 10  of showing the initial image to state S 19  showing the full text of the selected article of the television newspaper. 
     Finally, if the user issues a certain command in state S 10  of showing the initial image, the STB  30  may move to state S 20  where a service in sound is output from the loudspeaker  74  or to sate S 21  where a service of showing an environmental image on the display device  73 . It may be so arranged that an environmental image is displayed on the display device  73  when a service in sound is output from the loudspeaker  74 . 
     Now, referring to  FIG. 12 , the printer  32  comprises a digital video signal input section  80 , a monitor control signal input section  81 , a printing data extracting section  82 , a printing output processing section  83 , a printing head driver  84 , a printing head  85 , a printer control signal interface  86  and a printer CPU system  87 . In  FIG. 12 , the arrows show the flows of various signals being exchanged among the various components of the printer  32 . 
     The digital video signal input section  80  and the monitor control signal input section  81  correspond respectively to the digital video signal input section  70  and the monitor control signal input section  71  of the display  31  and are adapted to receive the respective video signals, which are a digital video signal and a monitor control signal, transmitted from the STB  30  and extract video data out of the video signals. 
     The printing data extracting section  82  receives the video data extracted by the digital video signal input section  80  and the monitor control signal input section  81  and extracts only the video data to be used for the printing operation of the printer  32  out of the received video data. 
     While the printing data extracting section  82  of the printer  32  may extracts the video data same as those of the images to be displayed on the display  31 , in the STB  30 , it extracts only the video data to be used by the printer  32  by the printing data extracting section  82  for printing when video signals containing both the video data showing by the display  31  for displaying images and those to be used by the printer  32  for printing images. 
     Thus, the printer  32  has the digital video signal input section  80 , the monitor control signal input section  81  and the printing data extracting section  82  as reception means for receiving video data transmitted from the STB  30 . However, the configuration of the reception means of the printer  32  is not limited to the above described one and may be modified appropriately so long as the reception means is adapted to receive the video data received by way of the above described first signal transmission means. 
     The printing output processing section  83  generates printing data to be used for printing images by means of the printing head on the basis of the video data obtained by the printing data extracting section  82  as a result of a data converting operation. 
     More specifically, the printing output processing section  83  is adapted to perform conversion processing operations using an LUT (look-up table), arithmetic processing operations using an arithmetic circuit that can carry out multiplications and additions at high speed, arithmetic processing operations using software containing a high speed arithmetic processing algorism and/or processing operations using a dedicated conversion circuit. However, when the printing output processing section  83  is adapted to sequentially carry out arithmetic processing operations, using a number of bits same as those of each input video data, the effective degree of accuracy of the data can more often than not be degraded. Therefore, it is desirable that the printing output processing section  83  increases the number of bits from those of each input video data in the course of the arithmetic processing operations and reduce the increased number of bits back to the original level in the final stages of the arithmetic processing operations so that the possible degradation of the effective degree of accuracy can be avoided. 
     In the printer  32 , the printing output processing section  83  operates as conversion processing means for processing the video data received by the above described reception means of the printer  32  in order to generate video data that are suited for printing images. While the conversion processing means is not indispensable for the purpose of the present invention, video data that are suited for printing images can be generated out of the video data that are suitable for displaying images and transmitted from the STB  30  to the display  31  so that high quality images may be printed if the printer  32  is provided with such a conversion processing means. 
     The printing head driver  84  generates drive signals for driving the printing head  85  on the basis of the printing data generated by the printing output processing section  83 . 
     The printing head  85  is driven by the drive signals generated by the printing head driver  84  and operates to print predetermined images on sheets of printing paper. While not shown in  FIG. 12 , the printer  32  comprises a sheet feeding section for feeding sheets of printing paper in addition to the printing head  85 . Since the sheet feeding section has a configuration same as its counterpart of any other ordinary printers, it will not be described here any further. 
     The printer  32  has the printing head driver  84  and the printing head  85  as printing means for printing images of the video data input to it. However, the configuration of the printing means of the printing means is not limited to the above described one and may be modified appropriately so long as the printing means is adapted to print images for the video data received by way of the above described reception means of the printer  32 . 
     The printer control signal interface  86  is connected to the printer system bus arranged within the printer  32  and adapted to exchange printer control signals with the STB  30 . More specifically, the printer control signal interface section  86  is equivalent to the above described printer control signal interface  66  of the STB  30  and operates to receive commands for starting and/or suspending printing operations sent from the STB  30  and transmitting information on the completion of a printing operation, an out-of-printing paper status in the printer  32  and so on to the STB  30 . 
     The printer CPU system  87  typically comprises a CPU, a program ROM, a RAM and a flash memory. The printer CPU system  87  is connected to the printer system bus arranged within the printer  32  and adapted to transmit and receive various control signals by way of the printer system bus in order to control the components of the printer  32 . More specifically, the printer CPU system  87  controls the components of the printer  32  according to the command received by the printer control signal interface section  86 , which may be a command for starting a printer operation. Additionally, the printer CPU system  87  receives information from each of the components of the printer  32  by way of the printer system bus processes the received information, which may be telling the completion of the current printing operation or an out-of-printing paper status. Then, the printer CPU system  87  transmits the processed information to the printer control signal interface section  86 . 
     Note that, in  FIG. 12 , the arrows showing the flows of various control signals being exchanged between the printer system bus and the components of the printer  32  are partly omitted. 
     Now, a specific configuration of the printing output processing section  83  will be described below. 
     Referring to  FIG. 13 , the printing output processing section  83  comprises an enlarging section  90 , an RGB-CMY converter  91 , a color correcting section  92 , a black extracting/base color removing section  93 , an output gamma correcting &amp; tone modifying section  94 , a sharpness modifying section  95  and an output characteristics converter  96 . In  FIG. 13 , the arrows show the flows of various signals being exchanged among the various components of the printing output processing section  83 . 
     The enlarging section  90  performs an enlarging operation on the input video data to obtain a number of pixels good for the current printing operation if the number of pixels of the video data in the form of RGB signals output from the printing data extracting section  82  is small when compared with the number of pixels of the image to be printed. 
     The enlarging section  90  typically receives video data of 720 p (720×1280 pixels) conforming to the standards of moving images of digital broadcasting as shown in  FIG. 14  from the printing data extracting section  82 . Then, if the printer  32  is adapted to print an image on a A4-size sheet of printing paper with 300 dpi, as shown in  FIG. 14 , the enlarging section  90  increases the number of pixels of the input video data by 2,675 times and transforms the received video data into video data for 1,926×3,424 pixels. 
     The RGB-CMY converter  91  processes the RGB signals of the video data subjected to the transforming operation of the enlarging section  90  to generate CMY signals that correspond to the inks or toners of C (cyan), M (magenta) and Y (yellow) that are used in the printing head  85 . The transforming operation may be realized typically by using the technique of density Log transform, complementary color transform or linear masking transform. 
     The color correcting section  92  corrects a color correcting operation on the CMY signals generated by the RGB-CMY converter  91 . With this operation, the printer  32  can corrects the discrepancy of the color tones or the hue and the color saturation of the image to be printed that can arise when the spectral absorption characteristics of the inks or the toners being used by the printing head  85  are different from the ideal characteristics obtained by the subtractive mixture of color stimuli. More specifically, the color correcting operation of the color correcting section  92  may be typically realized by means of an arithmetic converting operation using an LUT (look-up table), a linear masking technique or a non-linear masking technique. When the range of the chromatic characteristics that can be expressed by the video data input to the printer  32  differ from that of the chromatic characteristics that can be used for reproducing the image on a sheet of printing paper by the printing head  85 , the color correcting section  92  performs a compressing operation and/or a clipping operation on the video data for the chromatic characteristics. Then, if the video data input to the printer  32  have a range of chromatic characteristics that exceeds the one that can be used by the printing head  85  for image reproduction, the printer can optimally carry out the printing operation by efficiently utilizing the information on the chromatic characteristics contained in the video data. 
     The black extracting/base color removing section  93  extracts the black element and removes the base colors from the video that have been subjected to the color correcting operation of the color correcting section  92  if the printing head  85  is provided with black (hereinafter to be referred to as K) ink or toner. More specifically, the black extracting/base color removing section  93  extracts the K element contained in the CMY signals input from the color correcting section  92  and subtracts the value corresponding to the K element from each of the C, M and Y elements to generate CMYK signals comprising C, M, Y and K elements. 
     The operation of extracting the K element form CMY signals and replacing them with CMYK signals may be carried out typically by using a technique of extracting all the K element contained in CMY signals, that of extracting the K element by a predetermined ratio and replacing CMY signals with CMYK signals and that of extracting the K element in regions showing the element by more than a predetermined density level and replacing CMY signals with CMYK signals. 
     Thus, the printer  32  can print black to an optimal quality level that can hardly be reproduced simply by using C, M and Y inks or toners as a result of the operation of the black extracting/base color removing section  93  for converting CMY signals into CMYK signals and using black ink or toner for the K element contained in the CMY signals. Note that, if the printing head  85  of the printer  32  is not provided with black ink or toner, the black extracting/base color removing section  93  does not operate for the processing operation of extracting the black elements and replacing CMY signals with CMYK signals. If such is the case, the black extracting/base color removing section  93  may alternatively be omitted from the printing output processing section  83 . 
     The output gamma correcting &amp; tone modifying section  94  performs an operation of correcting the gamma modifying the tones of the video data in the form of CMYK signals produced from the black extracting/base color removing section  93 . More specifically, if the printing head  85  shows specific output characteristics in terms of the method of reproducing half tones, it performs an operation of correcting the gamma and modifying the tones of the input video data so as to make them adapted to the output characteristics. 
     The sharpness modifying section  95  performs an operation of emphasizing and smoothing the outlines of the images of the video data corrected and modified by the output gamma correcting &amp; tone modifying section  94 . As a result the quality of the images printed by the printer  32  can be improved. 
     The output characteristics converter  96  converts the characteristics of the video data processed by the sharpness modifying section  95  so as to optimize the quality of the image to be printed as a function of the type of the printing head  85 , the method of driving the printing head  85 , the type of the printing paper and the types of the inks or toners to be used for the printing operation as well as the ambient temperature at the time of the printing operation, the characteristics of the thermal history of the printing head  85  and the deviations of the performances of the printing elements provided at the printing head  85 . 
     Note, however, of the operations of converting the various characteristics of the video data, those that are suitably be performed by the printing head driver  84  may well be performed by it. 
     Now, a possible configuration of the printing output processing section  82  that may be employed when the printing head  85  is operated to use only black ink or toner for printing will be discussed by referring to  FIG. 15 . Note that, in  FIG. 15 , the components that are same as or similar to their respective counterparts in  FIG. 13  will be denoted respectively by the same reference symbols and will not be described any further. 
     When the printing head  85  is operated to use only black ink or toner for printing, the printing output processing section  83  is typically made to comprise an enlarging section  90 , an RGB-K converter  100 , an output gamma correcting &amp; tone modifying section  94 , a sharpness modifying section  95  and an output characteristics converter  96  shown in  FIG. 15 . Thus, in this case, the RGB-CMY converter  91 , the color correcting section  92  and the black extracting/base color removing section  93  of the above described printing output processing section  83  are replaced by an RGB-K converter  100 . The RGB-K converter  100  performs predetermined arithmetic operations according to the video data output as RGB signals from the enlarging section  90  to generate a K signal that contains only the density information of black (K). The RGB-K converter  100  typically generates a K signal on the basis of the brightness information Y that can be obtained by equation 1 below:
 
 Y= 0.2126 ×R+ 0.7152 ×G+ 0.0722 ×B   (equation 1),
 
where R, G and B respectively represent the brightness values of the R element, the G element and the B element of the RGB signals.
 
     As shown in  FIG. 15 , when the printing head  85  is adapted to print images in black (K) and white, using only black ink or toner, there can be cases where the printing head  85  cannot reproduce all the grey levels contained in the video data. Then, the sharpness modifying section  95  or the output characteristics converter  96  performs a dither operation according to the number of grey levels that can be reproduced by the printing head  85 . An ordered dither method or an error diffusion method may be used to express quasi-tones in the dither operation. 
     Now, a possible configuration of the printing head  85  will be described below by referring to an example where the printing head  85  of the printer  32  is applied to a so-called monochrome laser printer. 
     As shown in  FIG. 16 , the printing head  85  comprises a laser output section  110 , a polygon mirror  111 , a motor  112 , a lens  113 , a reflector mirror  114 , a photosensitive drum  115 , an electric charger  116 , a developing unit  117 , a transfer charger  118  and a pair of delivery rollers  119 ,  120 . 
     When the printing head  85  is adapted to operate for a monochrome laser printer, the video data converted into K signals by the printer output processing section  83  are further converted into laser output signals by the printing head driver  84  (which may comprise a laser control section and a laser driver in certain cases), which laser output signals are then output from the laser output section  110  as laser beam in synchronism with the operation of the polygon mirror  111 . 
     The laser beam output from the laser output section  110  is then reflected by the polygon mirror  111  that is driven to rotate by the motor  112 , which is by turn driven by polygon mirror drive section (not shown), and linearly scan the main surface of the photosensitive drum  115  by way of the lens  113  and the reflector mirror  114 . The photosensitive drum  115  is driven to rotate by a drum drive motor (not shown) around an axis of rotation that runs in parallel with the scanning direction of the laser beam. Additionally, the photosensitive drum  115  is electrically charged by the electric charger  116  so that a latent image corresponding to the video data is formed on the main surface of the photosensitive drum as the main surface is scanned by the laser beam. 
     Then, toner is supplied from the developing unit  117  to the latent image formed on the main surface of the photosensitive drum  115  to produce a toner image. As the toner image is brought to a position opposite to the transfer charger  119  by the rotary motion of the photosensitive drum  115 , it is transferred onto a printing paper delivered by the pair of delivery rollers  119 ,  120  from a paper feed section (not shown). Subsequently, the toner on the the printing paper  130  is fixed by a fixing unit (not shown) and delivered to the outside of the printer  32 . 
     While the printing operation of the printer  32  is described above in terms of a conventional monochrome laser printer, the present invention is by no means limited to the use of monochrome laser printers and can also be applied to color laser printers comprising a plurality of photosensitive drums, ink jet printers, thermal printers, sublimation type thermal printers and printers of many other types. 
     Now, typical operations of the STB  30 , the display  31  and the printer  32  will be described by referring to  FIGS. 17 through 19 . Note that, in the following description, specifically an operation where the printer  32  prints the image displayed on the display  31  without any modification and an operation where the printer  32  prints part of the image displayed on the display  31  or an image related to the image displayed on the display  31  will be described. 
     In the case of the former operation, the printer  32  receives the video signals transmitted from the STB  30  by way of the digital video signal input section  80  and the monitor control signal input section  81  and generates printing data out of the received video signals. On the other hand, in the case of the latter operation, the STB  30  generates part of the image displayed on the display  31  or an image to be printed that is related to the image display on the display  31  and transmits the signals related to the image to be printed to the printer  32 , using the gaps of the video signals transmitted to the display  31 . Then, the printer  32  receives the signals for the image to be printed that are transmitted by using the gaps of video signals and prints the image. 
     After the start of the operation, the STB  30  receives various broadcasts, synthetically combines them by means of the synthesizer  59  and stores the synthesized image in the video RAM as shown in Step S 30  in  FIG. 17 . The synthesized image may typically be an initial image as shown in  FIG. 10 . The STB  30  also transmits the video signals of the initial image to the display  31  and displays it on the display device  73  of the display  31 . 
     If no command is issued by the user for a predetermined period of time, the STB  30  selects the channel or the information address selected by the user last time from the flash memory of the CPU system  65  and causes it to be displayed on the display device  73  of the display  31  as shown in Step S 31 . 
     If a program is selected in Step S 31 , the STB  30  receives the program by means of the down converter  50  and the tuner  51  as shown in Step S 32 . 
     Then, in Step S 33 , the STB  30  performs a decoding operation by means of the descrambling section  54  and the video decoder  56 . 
     Then, in Step S 34 , the STB  30  synthetically by the synthesizer  59  combines the decoded video signals and the SI display signals and updates the image to be stored in the video RAM  60 . 
     If, on the other hand, an information address is selected in Step S 31 , the STB  30  accesses a telecommunication network and obtains the corresponding information typically by means of the modem  64  as shown in Step S 35  or receives the corresponding digital broadcasting and obtains the necessary information. 
     Then, in Step S 36 , the STB  30  decodes the obtained information typically by means of the data decoder  58  and the CPU system  65  and proceeds to the next step, or Step S 34 . 
     The image updated in Step S 34  is then generated as the image to be display on the display  31  in the video RAM  60  as shown in Step S 37 . 
     Then, in Step S 38 , the image to be displayed that is generated in the video RAM  60  is transmitted to the display  31  by way of the digital video signal output section  61  as video signals. 
     Thereafter, in Step S 39 , the display  31  receives the transmitted video signals and displays the corresponding image on the display device  73 . 
     Then, in Step S 40 , the I/O control section  63  of the STB  30  determines if the user inputs a command for selecting a broadcast program or an information address or not. If it is found that the user inputs a command for the selection, the STB  30  returns to Step S 32  or S 35 , where it receives a new broadcast program or a new information address. If, on the other hand, it is found that no command is input by the user, the STB  30  proceeds to Step S 41 . 
     In Step S 41 , the I/O control section  63  determines if the user inputs a command for starting a printing operation or not. If it is found that the user inputs a command for the start of a printing operation, the STB  30  proceeds to Step S 42  shown in  FIG. 18 . If, on the other hand, it is found that no command is input by the user, the STB  30  returns to Step S 32  or S 35  to continue the operation of receiving a broadcast program or an information address and updating the image to be displayed. 
     Then, in Step S 42  of  FIG. 18 , it is determined if the command for starting a printing operation input by the user is one for printing the image being displayed on the display  31  or one for printing part of the image being displayed on the display  31  or an image related to the image being displayed. The STB  30  proceeds to Step S 43  in the case of the former command, whereas it proceeds to Step S 44  shown in  FIG. 19  in the case of the latter command. 
     Then, in Step S 43 , the STB  30  suspends the operation of updating the image stored in the video RAM  60  and holds the predetermined image for the video signals to be transmitted to the display  31  and the printer  32  so that it may proceeds to Step S 46 . 
     Then, in Step S 46 , the STB  30  issues a command for starting a printing operation to the printer  32  by way of the printer control signal interface  66 . 
     Thereafter, in Step S 47 , the printer  32  receives the video signals transmitted from the STB  30  by way of the digital video signal input section  80  and the monitor control signal input section  81 . 
     Subsequently, in Step S 48 , the printer  32  extracts the video data for the image to be printed from the received video signals by using the printing data extracting section  82 . 
     Then, in Step S 49 , the printer  32  transforms the extracted image data into printing data suited for printing by using the printing output processing section  83 . 
     Thereafter, in Step S 50 , the printer  32  drives the printing head  85  according to the printing data, using the printing head driver  84 . 
     Subsequently, in Step S 51 , the printer  32  actually prints the image by means of the printing head  85 . 
     Then, in Step S 52 , the printer  32  determines if the printing operation is completed or not by way of the printer CPU system  87 . If the operation is completed, it proceeds to the nest step, or Step S 53 . If, on the other hand, the operation is not completed, it continues the printing operation and repeats the operation of Step S 52 . 
     Thereafter, in Step S 53 , the printer  32  transmits information to the STB  30  by way of the printer control interface section  86 , telling that the printing operation is completed. Upon receiving the information by way of the printer control interface  66 , the STB  30  returns the processing operation to Step S 32  or S 35  shown in  FIG. 17  and restarts the operation of updating the images stored in the video RAM  60 . 
     If the processing operation proceeds from Step S 42  to Step S 44 , the STB  30  transmits a command for starting a printing operation to the printer  32  by way of the printer control signal interface  66  in Step S 44 . 
     Then, in Step S 54  shown in  FIG. 19 , the printer CPU system  87  of the printer  32  determines if it is necessary to access a new broadcast program or an information address in order to obtain an image to be printed or not. If it is found that such access is necessary, it transmits a command for it to the STB by way of the printer control signal interface section  86  and the processing operation proceeds to the next step, which may be Step S 55  or S 56 . If, on the other hand, it is found that such access is not necessary, the processing operation proceeds to Step S 57 . 
     Then, in Step S 55 , the STB  30  receives the command from the printer  32  by way of the printer control signal interface  66  and obtains the program specified by the command before it proceeds to Step S 58 . 
     Thereafter, in Step S 58 , the STB  30  decodes the received broadcast program. 
     Then, in Step S 59 , the STB  30  generates video data to be used for printing out of the decoded broadcast program by means of the data decoder  58  or the CPU system  65  and proceeds to the nest step, or Step S 57 . 
     In Step S 56 , the STB  30  receives a command from the printer  32  by way of the printer control signal interface  66  along with a new information address and proceeds to Step S 60 . 
     Then, in Step S 60 , the STB  30  decodes the received information address and moves to Step S 59 . 
     In Step  557 , the STB  30  transmits the video data for printing to the printer out of the time used for transmitting the video data to the display  31  by means of the digital video signal output section  61  and the monitor control signal output section  62 . Then, it proceeds to Step S 61 . 
     In Step S 61 , the printer  32  receives the video signal transmitted from the STB  30  by means of the digital video signal input section  80  and the monitor control signal input section  81 . Additionally, it extracts the video to be used for printing by means of the printing data extracting section  82  out of the video data it receives. 
     Then, in Step S 62 , the printer  32  transforms the video data extracted for printing into printing data adapted for printing by means of the printing output processing section  83 . 
     Thereafter, in Step S 63 , the printer  32  drives the printing head  85  by means of the printing head driver  84  according to the printing data. 
     Subsequently, in Step S 64 , the printer  32  carries out the printing operation by means of the printing head  85 . 
     Then, in Step S 65 , the printer  32  determines if the printing operation is completed or not by means of the printer CPU system  87 . If it is found that the operation is completed, the printer  32  proceeds to Step S 32  or S 35  shown in  FIG. 17  so that the STB  30  resumes the operation of receiving a broadcast program or an information address and updating the data stored in the video RAM  60 . If, on the other hand, it is found that the operation is not completed, the printer  32  continues the printing operation and repeats the operation of Step S 65 . 
     Embodiment 2 
     Now, a second embodiment of the present invention will be described below. As shown in  FIG. 20 , this second embodiment differs from the above described first embodiment in that a printing image RAM  140  is added to the downstream of the printing data extracting section  82 . The components that are same as those of the printer  32  shown in  FIG. 10  are denoted respectively by the same reference symbols in  FIG. 20  and will not be described any further. 
     The printing image RAM  140  operates to temporarily store at least part of the video data extracted by the printing data extracting section  82  and the printer  32  is adapted to output the video data stored in the printing image RAM  140  to the printing output processing section  83 . The printer  32  normally has to spend a long period of time until the completion of a printing operation if compared with the time spent for receiving video data to be used for the printing operation from the STB  30 . Because of this fact, in the above first embodiment, the operation of updating the data stored in the video RAM  60  of the STB  30  is suspended until the printing operation of the printer  32  is completed in order to continuously transmit certain video data temporarily stored in the video RAM  60  as described above by referring to Step S 43  in  FIG. 18 . In other words, in the first embodiment, the image displayed on the display  31  is not updated and the display  31  keeps on displaying a given still image until the printing operation of the printer  32  is completed. While this may provide an advantage that the user can easily recognize that the printer  32  is operating for printing an image, the user has to forcibly and disadvantageously suspend his or her viewing of the broadcast program. 
     To the contrary, since the printer  32  of the second embodiment is provided with a printing image RAM  140 , it can temporarily hold at least part of the video data transmitted from the STB  30  so that, if a sufficient amount of video data to be used for printing images is stored in the printing image RAM  140 , the STB  30  can resume the operation of updating the data stored in the video RAM without waiting for the completion of the printing operation. As a result, the time period during which the user is forced to suspend viewing the broadcast program can be significantly reduced. 
     While the printing image RAM  140  is not subjected to any limitations in terms of storage capacity for the purpose of the present invention, it preferably has a storage capacity sufficient for temporarily storing all the video data to be used for a printing operation. Then, if a considerable time is required for the completion of the printing operation, the STB  30  does not need to suspend the operation of updating the data stored in the video RAM  60  and hence the user is not forced to suspend his or her viewing of the broadcast program. 
     Note that the printing image RAM  140  may be arranged downstream relative to the printing output processing section  83  instead of downstream relative to the printing data extracting section  82 . With this arrangement, the time period during which the user is forced to suspend viewing the broadcast program can be also significantly reduced if the time required for the processing operation of the printing output processing section  83  is short enough. 
     Embodiment 3 
     Now, a third embodiment of the present invention will be described below. In this third embodiment, the printer  32  is adapted to develop part of the information contained in the digital broadcasting received by the STB  30 . 
     In this third embodiment, the STB  30  is additionally provided with an SI printing signal output section  150  as shown in  FIG. 21  while the printer  32  is additionally provided with an SI printing signal input section  151 , a data decoder  152 , a synthesizer  153  and a printing image RAM  154  as shown in  FIG. 22 . Furthermore, the printer CPU system  87  of the printer  32  is provided with a font ROM. The SI printing signal output section  150  of the STB  30  and the SI printing signal input section  151  of the printer  32  are connected to each other by means of the above described second signal transmission means or some other signal transmission means that is equivalent to the second signal transmission means. 
     The components that are same as those of the STB  30  and those of the printer  32  shown respectively in  FIG. 8  and  FIG. 10  are denoted respectively by the same reference symbols in  FIG. 21  and  FIG. 22  and will not be described any further. 
     The STB  30  of this embodiment is adapted to isolate the packet of a target program out of the input stream where video signals and audio signals are multiplexed according to the MPEG-2 Standards by means of the packet isolator  55  and also the information other than video signals and audio signals, which is referred to as SI control signal, by means of the data decoder  58 . The isolated SI control signal is then output to the CPU system  65 . The CPU system  65  of the STB  30  generates and/or extracts the information to be developed by the printer  32  as SI printing signal on the basis of the SI control signal output from the data decoder  58 , which SI printing signal is then output it to the SI printing signal output section  150 . Then, the SI printing signal output section  150  transmits the SI printing signal to the printer  32  byway of the second signal transmission means or some other signal transmission means that is equivalent to the second signal transmission means. 
     Note that an SI printing signal is a signal containing less information than the corresponding video data. It is typically processed by the data decoder  152  of the printer  32  in a predetermined way to generate service information and character information. 
     Then, the printer  32  receives the SI printing signal transmitted from the STB  30  by way of the SI printing signal input section  151 . The SI printing signal received by the SI printing signal input section  151  is then input to the data decoder  152 . The data decoder  152  decodes the SI printing signal and outputs the part of the decoded SI printing signal that can be directly developed into displayable data to the synthesizer  153  and the remaining part of the decoded SI printing signal that cannot be directly developed into displayable data to the CPU system  87  by way of the system bus as SI control signal. 
     The SI control signal output to the printer CPU system  87  is then processed by the latter and output to the synthesizer  153  as SI recording signal. More specifically, the printer CPU system  87  transforms the SI control signal into a displayable SI recording signal by way of a processing operation using the font data stored in the font ROM. 
     The synthesizer  153  is equivalent to the synthesizer  59  of the STB  30  and adapted to receive the video data extracted by the printing data extracting section  82 , the SI printing signal output from the data decoder  152  and the SI recording signal produced as a result of the transforming operation of the printer CPU system  87  and synthetically combines them before storing them into the printing image RAM  154 . The video data synthetically combined and stored into the printing image RAM  154  are then output to the printing output processing section  83 . 
     In this embodiment, data containing a large amount of information such as video data are transmitted from the STB  30  to the printer  32  by way of the high speed first signal transmission means, while data containing a relatively small amount of information such as service information and character information are transmitted from the STB  30  to the printer  32  by way of the second signal transmission means that transmits data only at a rate lower than the first signal transmission means. Therefore, in this embodiment, it is possible to generate service information and character information by means of not the STB  30  but the printer  32  and the first signal transmission means can be dedicated to the transmission of video data. Thus, any possible delay of signal transmission that can be caused by transmitting data other than video data by means of the first signal transmission means can be avoided in this embodiment. 
     Embodiment 4 
     Now, a fourth embodiment of the present invention will be described below. This embodiment resembles the above described third embodiment in that part of the information contained in the digital broadcasting received by the STB  30  is developed and processed by the printer  32 . 
     In this fourth embodiment, the STB  30  is additionally provided with a data stream signal output section  160  as shown in  FIG. 23 , while the printer  32  is additionally provided with a data stream signal input section  161 , a packet isolator  162 , a data decoder  163 , a synthesizer  164  and printing image RAM  165  as shown in  FIG. 24 . Furthermore, the printer CPU system  87  of the printer  32  is provided with a font ROM. The data stream signal output section  160  of the STB  30  and the data stream input section  161  of the printer  32  are connected to each other by way of the second signal transmission means or some other signal transmission means that is equivalent to the second signal transmission means. 
     The components that are same as those of the STB  30  and those of the printer  32  shown respectively in  FIG. 8  and  FIG. 10  are denoted respectively by the same reference symbols in  FIG. 23  and  FIG. 24  and will not be described any further. 
     The STB  30  of this embodiment outputs the data stream signal that is descrambled by the descrambling section  54  to the packet isolator  55  and the data stream signal output section- 160 . The data stream signal output section  160  transmits the data stream signal it receives to the printer  32  by way of the second signal transmission means or some other signal transmission means that is equivalent to the second signal transmission means. 
     A data stream signal is a signal before being subjected to a packet isolating operation of the packet isolator  55  of taking out the packet of a desired program, from which service information and character information will typically be generated by the packet isolator  162  of the printer  32 . 
     The printer  32  receives the data stream signal transmitted from the STB  30  by way of its data stream signal input section  161 . The data stream signal received by the data stream signal input section  161  is then input to the packet isolator  162 . The packet isolator  162  is adapted to operate substantially same as the packet isolator  55  of the STB  30  so that it takes out the packet of the desired program from the data stream signal. The packet isolator  162  then outputs the taken out packet to the data decoder  163 . 
     The data decoder  163  decodes the data of the packet taken out by the packet isolator  162  and outputs the part of the decoded signal that can be directly developed into printable data to the synthesizer  164  as SI printing signal and the remaining part of the decoded signal that cannot be directly developed into printable data to the printer CPU system  87  by way of the system bus as SI control signal. 
     The SI control signal output to the printer CPU system  87  is processed by the latter and output to the synthesizer  164  as SI recording signal. More specifically, the printer CPU system  87  transforms the SI control signal into a printable SI recording signal by way of a processing operation using the font data stored in the font ROM. 
     The synthesizer  164  is equivalent to the synthesizer  59  of the STB  30  and adapted to receive the video data extracted by the printing data extracting section  82 , the SI printing signal output from the data decoder  163  and the SI recording signal produced as a result of the transforming operation of the printer CPU system  87  and synthetically combines them before storing them into the printing image RAM  165 . The video data synthetically combined and stored into the printing image RAM  165  are then output to the printing output processing section  83 . 
     Thus, in this embodiment again, data containing a large amount of information such as video data are transmitted from the STB  30  to the printer  32  by way of the high speed first signal transmission means, while data containing a relatively small amount of information such as service information and character information are transmitted from the STB  30  to the printer  32  by way of the second signal transmission means that transmits data only at a rate lower than the first signal transmission means. Therefore, in this embodiment, it is possible to generate service information and character information by means of not the STB  30  but the printer  32  and the first signal transmission means can be dedicated to the transmission of video data. Thus, any possible delay of signal transmission that can be caused by transmitting data other than video data by means of the first signal transmission means can be avoided in this embodiment just like the above described third embodiment. 
     Embodiment 5 
     Now, a fifth embodiment of the present invention will be described below. In this embodiment, the printer  32  is provided with a feature of receiving digital broadcasting apart from the STB  30 . 
     Referring to  FIG. 25 , illustrating the configuration of the printer  32  of the fifth embodiment, the printer  32  comprises a down converter  170 , a tuner  171 , a digital demodulator  172 , an error correcting section  173 , a descrambling section  174 , a packet isolator  175 , a data decoder  176 , a synthesizer  177 , a printing image RAM  178  and a modem  179  in addition to the components of the printer  32  of the first embodiment. Additionally, the printer CPU system  87  of the printer  32  is provided with a font ROM. 
     The components that are same as those of the printer  32  shown in  FIG. 10  are denoted by the same reference symbols in  FIG. 25  and will not be described any further. 
     The down converter  170 , the tuner  171 , the digital demodulator  172 , the error correcting section  173 , the descrambling section  174 , the packet isolator  175  and the data decoder  176  correspond respectively to the down converter  50 , the tuner  51 , the digital demodulator  52 , the error correcting section  53 , the descrambling section  54 , the packet isolator  55  and the data decoder  58  of the above described STB  30 . In other words, the printer  32  of this embodiment is provided with a digital broadcasting reception means substantially same as that of the STB  30 . 
     However, in the printer  32 , the packet isolated by the packet isolator  175  is output only to the data decoder  176 . Then, the data decoder  176  decodes only the SI information without decoding the video data and the audio data contained in the packet. Thereafter, the data decoder  176  outputs the part of the decoded SI signal that can be directly developed into printable data to the synthesizer  177  as SI printing signal and the remaining part of the decoded signal that cannot be directly developed into printable data to the printer CPU system  87  by way of the system bus as SI control signal. 
     The SI control signal output to the printer CPU system  87  is processed by the latter and output to the synthesizer  177  as SI recording signal. More specifically, the printer CPU system  87  transforms the SI control signal into a printable SI recording signal by way of a processing operation using the font data stored in the font ROM. 
     The synthesizer  177  is equivalent to the synthesizer  59  of the STB  30  and adapted to receive the video data extracted by the printing data extracting section  82 , the SI printing signal output from the data decoder  176  and the SI recording signal produced as a result of the transforming operation of the printer CPU system  87  and synthetically combines them before storing them into the printing image RAM  178 . The video data synthetically combined and stored into the printing image RAM- 178  are then output to the printing output processing section  83 . 
     As described above, the printer  32  is provided with a feature of receiving digital broadcasting apart from the STB  30 . As a result, the printer  32  can obtain service information and/or character information out of a given broadcast program according to a predetermined signal contained in the printer control signal received by way of the printer control signal interface section  86  apart from the video data to be displayed on the display  31 . Thus, the printer  32  now can not only print the video data to be displayed on the display  31  but also independently access a broadcast program and/or an information address so that it can perform printing operations in a very flexible way. 
     The modem  179  is substantially equivalent to the modem  64  of the above described STB  30  and hence can transmit and receive various information by way of a telecommunication network such as a telephone line, while it is connected to the printer system bus arranged within the printer  32 . 
     Since the printer  32  of this embodiment is provided with a modem  179 , which can access a telecommunication network independently from the modem  64  of the STB  30  so that the printer  32  can obtain service information and/or character information in a very flexible way. 
     While the present information is described above by referring to the first through fifth embodiments, all the embodiments comprise an STB  30 , a display  31  and a printer  32  as independent units thereof for the receiving section, the display section and the printing section that are indispensable components for realizing the present invention. 
     However, the present invention is by no limited to the arrangement of comprising the receiving section the display section and the printing section as independent units. For example, more than two of the receiving section, the display section and the printing section may be integrally combined as in the case of  FIG. 1  showing a digital television receiving set  10 ,  FIG. 5  showing a digital television receiving set  20  and a printer  21  and  FIG. 7  showing an STB  40  and a display  41 . Any of such arrangements can provide the advantages as described above by referring to the first through fifth embodiments. 
     If more than two of the receiving section, the display section and the printing section are integrally combined, certain components of the above described embodiments may be omitted appropriately. For example, as shown in  FIG. 7 , if the STB  30  and the display  41  are combined integrally, the system bus of the STB  30  and the printer system bus of the printer  31  of the first embodiment may be connected to omit the printer CPU system  87  so that the components of the printing section may be controlled by the CPU system  65  of the STB  30 . Then, the printer control signal interface  66  of the STB  30  and the printer control signal interface section  86  of the printer  31  may also be omitted.