Patent Publication Number: US-2005125819-A1

Title: Broadcast receiving apparatus, control method and program therefor

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a broadcast receiving apparatus, a control method and a program therefor, applicable to a television receiver of a configuration, separated into a receiving portion for receiving a television broadcast wave and a display portion for displaying an image of the television broadcasting in which both portions are connected by a wireless or wired link and including a recording apparatus in the receiving portion.  
      2. Related Background Art  
      In order to meet a requirement of enjoying television viewing in an arbitrary location without being restricted by an antenna cable, there is proposed a technology, for a television receiver provided with a receiving portion connected to an antenna for receiving a television broadcast wave and a display portion for displaying an image of the television broadcasting, of transmitting signals between the receiving portion and the display portion by a wireless link (for example patent reference 1). 
          Patent reference 1: Japanese Patent Application Laid-Open No. 2001-358966 (US AA 2002059585)        

      However, such prior technology does not have measures against a failure in the wireless transmission between the receiving portion and the display portion of the television receiver, or against a battery capacity deficiency in case the display portion is driven by a battery. Also in a configuration including, in the receiving portion, a recording portion for recording a broadcast program, the broadcast program can no longer be viewed in case of a failure in the display portion though the program can be recorded in the recording portion.  
     SUMMARY OF THE INVENTION  
      An object of the present invention is to provide a broadcast receiving apparatus, a control method and a program, which allow, in case of a deterioration in a reception state of a child device, to view a broadcast program, that has been viewed in the child device, automatically and in continuation in a parent device.  
      For attaining the aforementioned object, the present invention is characterized by a broadcast receiver including a parent device capable of receiving a broadcast wave and displaying a broadcast program and a child device constructed communicably with the parent device and capable of displaying a broadcast program based on broadcast data transmitted from the parent device, wherein the child device includes watching means which watches a reception status of the child device, and the parent device includes control means which, in response to a notice from the child device for a worsened reception state, enables the parent device to display a broadcast program that has been displayed on the child device.  
      The present invention is also characterized by a broadcast receiver including a parent device capable of receiving a broadcast wave and displaying a broadcast program and a child device constructed communicably with the parent device and capable of displaying a broadcast program based on broadcast data transmitted from the parent device, wherein the child device includes watching means which watches a remainder charge of a battery for driving the child device and the parent device includes control means which, in response to a notice from the child device for a remainder charge of the battery less than a set value, enables the parent device to display a broadcast program that has been displayed on the child device.  
      The present invention is also characterized by a broadcast receiver including a parent device capable of receiving a broadcast wave and displaying a broadcast program and a child device constructed communicably with the parent device and capable of displaying a broadcast program based on broadcast data transmitted from the parent device, wherein the child device includes watching means which watches a reception status of the child device and a remainder charge of a battery for driving the child device, and the parent device includes control means which, in response to a notice from the child device for a worsened reception state or a remainder charge of the battery less than a set value, enables the parent device to record a broadcast program that has been displayed on the child device.  
      The present invention is also characterized by a broadcast receiver including a parent device capable of receiving a broadcast wave and displaying a broadcast program and a child device constructed communicably with the parent device and capable of displaying a broadcast program based on broadcast data transmitted from the parent device, wherein the child device includes informing means which periodically transmits a status information indicating a normal reception during the display of the broadcast program on the child device, and the parent device includes control means which, in response to an interruption of the status information from the child device, enables the parent device to record the broadcast program that has been displayed on the child device.  
      Furthermore, the present invention may adopt a configuration in which, in case of a worsened reception status of the child device, a user can select either to display the broadcast program that has been displayed in the child device, in the parent device, or to record the broadcast program that has been displayed in the child device, in the parent device.  
      Furthermore, the present invention may adopt a configuration in which, in case a remainder charge of a battery of the child device becomes less than a set value, the user can select either to display the broadcast program that has been displayed in the child device, in the parent device, or to record the broadcast program that has been displayed in the child device, in the parent device.  
      Furthermore, the present invention may adopt a configuration in which, in case of a worsened reception status of the child device or in case a remainder charge of a battery of the child device becomes less than a set value, the user can select either to record the broadcast program that has been displayed in the child device, in the parent device or to display the broadcast program that has been displayed in the child device, in the parent device.  
      Furthermore, the present invention may adopt a configuration in which, in case a status information indicating a normal reception is not transmitted from the child device to the parent device, the user can select either to record the broadcast program that has been displayed in the child device, in the parent device or to display the broadcast program that has been displayed in the child device, in the parent device.  
      Thus in the present invention, as a reception status is watched during a display of a broadcast program in the child device and the parent device, in response to a notice from the child device for a worsened reception state, displays the broadcast program that has been displayed on the child device, there is provided an effect that the user can automatically continue to view the broadcast program, which has been viewed in the child device, in the parent device.  
      Also in the present invention, as the parent device, in response to a notice from the child device for a worsened reception state, terminates a transmission of broadcast data to the child device and displays the broadcast program that has been displayed on the child device, in the parent device in case a continued viewing is desired, there is provided an effect that the user can automatically continue to view the broadcast program, which has been viewed in the child device, in the parent device.  
      Also in the present invention, as a remainder charge of a battery for driving the child device is watched during a display of a broadcast program in the child device and the parent device, in response to a notice from the child device for a remainder charge of the battery less than a set value, displays on the parent device the broadcast program that has been displayed on the child device, there is provided an effect that the user can automatically continue to view the broadcast program, which has been viewed in the child device, in the parent device.  
      Also in the present invention, as the parent device, in response to a notice from the child device for a remainder charge of the battery less than a set value, terminates a transmission of broadcast data to the child device and displays the broadcast program that has been displayed on the child device, in the parent device in case a continued viewing is desired, there is provided an effect that the user can automatically continue to view the broadcast program, which has been viewed in the child device, in the parent device.  
      Also in the present invention, as a reception status of the child device and a remainder charge of a battery for driving the child device are watched during a display of a broadcast program in the child device and, in case the parent device receives a notice from the child device for a worsened reception state or a remainder charge of the battery less than a set value, the broadcast program that has been displayed in the child device is recorded in the parent device, there is provided an effect that the user can automatically record, in the parent device, the broadcast program which has been viewed in the child device.  
      Also in the present invention, in case the worsened reception state or the remainder charge of the battery less than a set value in the child device is resolved, the parent device informs the child device that the broadcast program recorded in the patent device can be reproduced in the child device, so that there is provided an effect that the user can view a continuation of the broadcast program, which the user has interrupted to view, can be reproduced and viewed in the child device.  
      Also in the present invention, as a status information indicating a normal reception during a display of a broadcast program on the child device is periodically transmitted from the child device to the parent device and the parent device, in case of an interruption of the status information from the child device, enables the parent device to record the broadcast program that has been displayed on the child device, there is provided an effect that the broadcast program that has been displayed in the child device can be automatically recorded in the parent device.  
      Also in the present invention, in case the status information is sent again from the child device to the parent device, control means of the parent device informs the child device that the broadcast program recorded in the patent device can be reproduced in the child device, so that there is provided an effect that the user can view a continuation of the broadcast program, which the user has interrupted to view, can be reproduced and viewed in the child device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block diagram showing a configuration of a parent/child television system constituting a first embodiment of the present invention;  
       FIG. 2  is a flow chart showing operations in case a reception status is worsened in the parent/child television system;  
       FIG. 3  is a continuation of the flow chart shown in  FIG. 2 ;  
       FIG. 4  is a block diagram showing a configuration of a parent/child television system constituting a second embodiment of the present invention;  
       FIG. 5  is a flow chart showing operations in case a remainder charge in a battery is lowered in the parent/child television system;  
       FIG. 6  is a continuation of the flow chart shown in  FIG. 5 ;  
       FIG. 7  is comprised of  FIGS. 7A and 7B  showing block diagrams of a configuration of a parent/child television system constituting a third embodiment of the present invention;  
       FIG. 8  is a flow chart showing operations in case a reception status is worsened or a remainder charge in a battery is lowered in the parent/child television system;  
       FIG. 9  is a continuation of the flow chart shown in  FIG. 8 ;  
       FIG. 10  is a continuation of the flow chart shown in  FIG. 9 ;  
       FIG. 11  is a continuation of the flow chart shown in  FIG. 10 ;  
       FIG. 12  is a continuation of the flow chart shown in  FIG. 11 ;  
       FIG. 13  is a view showing an example of a menu image prepared by an OSD processor of the parent device; and  
       FIG. 14  is a flow chart showing operations of a parent/child television system constituting a fourth embodiment of the present invention;  
       FIG. 15  is a continuation of the flow chart shown in  FIG. 14 ; and  
       FIG. 16  is a continuation of the flow chart shown in  FIG. 15 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      In the following the present invention will be clarified in details by embodiments thereof, with reference to the accompanying drawings.  
     First Embodiment  
       FIG. 1  is a block diagram showing a configuration of a parent/child television system constituting a first embodiment of the present invention.  
      Referring to  FIG. 1 , a parent/child television system is provided with an antenna  1  for receiving a digital broadcast wave transmitted from a broadcasting station, a parent device A 100  for executing a video display and an audio reproduction based on the digital broadcast wave received by the antenna  1 , a child device B 200  for executing a video display and an audio reproduction based on a transport stream data outputted from the parent device A 100 , and a remote control  33  for various instructions to the parent/child television system by a user.  
      In the present embodiment, a digital broadcasting receivable by the parent/child television system is based on a digital broadcasting system standards of DVB (digital video broadcasting), in which a video signal and an audio signal are respectively transmitted from the broadcasting station according to an MPEG2 (Moving Picture Experts Group 2) standard of ISO/IEC (International Organization for Standardization/International Electrotechnical Commission) 61818-2 and an MPEG2 standard of ISO/IEC 61818-3.  
      The present embodiment explains a case of satellite broadcasting as an example of the digital broadcasting to be received by the parent/child television system from the broadcasting station, but the present invention is not limited to such satellite broadcasting but is applicable to a case of receiving a cable television broadcasting through a coaxial cable or an optical fiber cable, or a case of receiving a broadband broadcasting through a broadband network.  
      At first there will be explained a configuration of the parent device A 100 . The parent device A 100  is capable of a wireless communication with a child device B 200  to be explained later. A digital tuner A 2  and a digital tuner B 12  of the parent device A 100  are respectively connected to the antenna  1 . The antenna  1  is used for receiving a digital broadcast wave. A CPU-A (control means)  38  controls various units of the parent device A 100  according to a program, and executes a process of the parent device side in flow charts shown in  FIGS. 2 and 3 . A program ROM  36  stores the aforementioned program.  
      A common bus  31  constitutes a signal transmission path for connecting the CPU-A  38  and various units. The common bus  31  is connected, in addition to the CPU-A  38  and the program ROM  36 , to a remote control interface  32  for receiving an infrared code of the remote control  33  and transmitting it to the CPU-A  38 , a RAM  34  constituting a work memory of the CPU-A  38 , and a non-volatile memory  37  for memorizing information that should not be erased, such as information of a broadcasting channel that has been selected immediately before the power supply of the present television system is turned off. The remote control  33  is provided with a decision key, a decision cancel key, a cursor key (foregoing keys not shown) etc. to be explained later.  
      The digital tuner A 2  and the digital tuner B 12  respectively select desired frequencies according to an instruction of the CPU-A  38  from the broadcast waves received by the antenna  1 . Signals outputted from the digital tuner A 2  and the digital tuner B 12  are subjected to a demodulation and an error correction respectively by a demodulation/error correction circuit A 3  and a demodulation/error correction circuit B 13  and outputted as transport streams.  
      The transport stream data outputted from the demodulation/error correction circuit A 3  are supplied to a demultiplexer A 5 . The demultiplexer A 5  selects, from the multiplexed stream, a stream having a PID (packet identifier) designated by the CPU-A  38 , and sends a video stream to a video decoder A 6  and an audio stream to an audio decoder A 7 . Further the demultiplexer A 5  also selects information on time and broadcast program content, called SI (system information) contained in the transport stream and transfers it to the CPU-A  38 .  
      The video stream is decoded by the video decoder A 6  into a non-compressed video data, thereby providing an image. An OSD (on screen display) processor A 9 , executing a video signal processing for displaying various messages according to data supplied from the CPU-A  38 , is so-called text/graphics process circuit for displaying information such as a character, a picture or a symbol other than the image of the broadcast program. In case of displaying a message, information for displaying a message is supplied from the CPU-A  38  to the OSD processor A 9 , which synthesizes the message display information with the video signal from the video decoder A 6 . The synthesized image is displayed on a display A 10 .  
      Also the audio stream supplied from the demultiplexer A 5  to the audio decoder A 7  is decoded by the audio decoder A 7  into a non-compressed audio data, which are outputted, after amplified by an amplifier A 18 , as a voice from a speaker A 19 .  
      On the other hand, the transport stream data outputted from the demodulation/error correction circuit B 13  are supplied to a transmission processor A 23 , which, according to a control signal from the CPU-A  38 , executes a transmission rate modulation and an amplification of a transmission signal to the child device B 200 . The transmission signal processed in the transmission processor A 23  is wireless transmitted through a shared device A 24  and a transmission/reception antenna  26  to the child device B 200 .  
      The shared device A 24  prevents an interference between a transmission signal to the child device B 200  and a reception signal from the child device B 200 . A parent device status, indicating a state of the parent device A 100  is also sent, when necessary, from the CPU-A  38  to the transmission processor A 23  and can be transmitted as parent device status information to the child device B 200  through the shared device A 24  and the transmission/reception antenna  26 .  
      A wireless signal transmitted from the child device B 200  to the parent device A 100  is received by wireless through the transmission/reception antenna  26  and the shared device A 24 , then subjected to a demodulation and an error correction by a demodulation/error correction circuit C 25  and transmitted as key information or child status information from the child device B 200  to the CPU-A  38 .  
      In the following, the configuration of the child device B 200  will be explained. The child device B 200  is constructed as a portable device provided with a thin and light display such as a liquid crystal display, and can be installed in any location without requiring a connection with an external antenna, within a range capable of wireless communication with the parent device A 100 . A CPU-B  58  (watching means) controls various units of the child device B 200  according to a program, and executes a process of the child device side in the flow charts shown in  FIGS. 2 and 3 . A program ROM  56  stores the aforementioned program.  
      A common bus  51  constitutes a signal transmission path for connecting the CPU-B  58  and various units. The common bus  51  is connected, in addition to the CPU-B  58  and the program ROM  56 , to a RAM  54  constituting a work memory of the CPU-B  58 , and a non-volatile memory  57  for memorizing information that should not be erased, such as information of a broadcasting channel that has been selected immediately before the power supply of the present television system is turned off.  
      Wireless transport stream data transmitted from the parent device A 100  to the child device B 200  is received by wireless through a transmission/reception antenna  40  and a shared device B 41 , then subjected to a demodulation and an error correction by a demodulation/error correction circuit D 42 , thus being demodulated into transport stream data, and further supplied to a demultiplexer B 43 . The demultiplexer B 43  selects, from the multiplexed stream, a stream having a PID designated by the CPU-B  58 , and sends a video stream to a video decoder B 44  and an audio stream to an audio decoder B 48 .  
      The video stream is decoded by the video decoder B 44  into a non-compressed video data, thereby providing an image. An OSD processor B 46 , executing a video signal processing for displaying various messages according to data supplied from the CPU-A  38 , is so-called text/graphics process circuit for displaying information such as a character, a picture or a symbol other than the image of the broadcast program. In case of displaying a message, information for displaying a message is supplied from the CPU-B  58  to the OSD processor B 46 , which synthesizes the message display information with the video signal from the video decoder B 44 . The synthesized image is displayed on a display B 47 , such as a liquid crystal display.  
      Also the audio stream supplied from the demultiplexer B 43  to the audio decoder B 48  is decoded by the audio decoder B 48  into a non-compressed audio data, which are amplified by an amplifier B 49  and outputted as a voice from a speaker B 50 .  
      The child device B 200  receives, in addition to the wireless transport stream data from the parent device A 100 , parent device status information, transmitted by wireless communication, through the transmission/reception antenna  40  and the shared device B 41 , then subjected to a demodulation and an error correction by the demodulation/error correction circuit D 42  to generate parent device status information which is transmitted to the CPU-B  58 .  
      Keys  64  is constituted of channel up/down keys for selecting a channel of the received digital broadcasting, volume up/down keys for regulating a sound volume of the received digital broadcasting, and a power key for turning on/off the power supply of the child device B 200  (these keys not shown). When the volume up key, the volume down key or the child device power key is depressed by the user, as the present television system is so constructed as to execute processes corresponding to these key operations within the child device B 200 , a key interface  63  transmits a code corresponding to a key to the CPU-B 58 , which thus executes an operation corresponding to the depressed key (volume up/down, power supply on/off).  
      On the other hand, when the channel up key or the channel down key is depressed by the user, since the present television system is so constructed that the channel up/down information has to be informed from the child device B 200  to the parent device A 100 , the key interface  63  transmits a code corresponding to a key to a transmission processor B 52 , which executes a transmission rate modulation process or an amplification process according to a control signal from the CPU-B  58 .  
      Also a transmission signal processed in the transmission processor B 52  is transmitted by wireless as key information, through the shared device B 41  and the transmission/reception antenna  40 , to the parent device A 100 . A child device status, indicating a state of the child device B 200  is also sent, when necessary, from the CPU-B  58  to the transmission processor B 52  and is transmitted as child device status information to the parent device A 100  through the shared device B 41  and the transmission/reception antenna  40 .  
      The parent device A 100  receives the information from the child device B 200  by wireless and through the transmission/reception antenna  26  and the shared device A 24 , and the information is then subjected to a demodulation and an error correction by the demodulation/error correction circuit C 25  and transmitted as key information or child status information from the child device B 200  to the CPU-A  38 . The CPU-A  38  issues an instruction, based on the key information corresponding to the depression of the channel up key or the channel down key in the child device B 200 , to the digital tuner B 12  for a change to a desired frequency. When the broadcast channel is changed by a frequency change in the digital tuner B 12 , corresponding transport stream data are supplied from the parent device A 100  to the child device B 200  and are decoded as explained in the foregoing.  
      In the following there will be explained, with reference to flow charts shown in  FIGS. 2 and 3 , operations when a reception state becomes worse while the user enjoys, in the parent/child television system of the present embodiment, a digital broadcasting in the child device B 200  by receiving transport stream data utilizing the digital tuner B 12  of the parent device A 100 .  
      Referring to  FIGS. 2 and 3 , the demodulation/error correction circuit D 42  of the child device B 200  constantly measures an error rate in the transport stream data received from the patent device A 100 , and the CPU-B  58  of the child device B 200  constantly watches the measured error rate (step S 111 ). When the error rate exceeds a certain value, the demodulation/error correction circuit D 42  becomes incapable of error correction, whereby the video decoder B 44  or the audio decoder B 48  cannot execute a proper decoding process. Since the child device B 200  is movable as mentioned above, the reception state may change by a displacement of the child device B 200  during the reception of the broadcasting.  
      When the CPU-B 58  of the child device B 200 , watching the error rate measured by the demodulation/error correction circuit D 42  judges that the error rate has exceeded a certain value (threshold value) (step S 112 ), and when a state where the error rate exceeds the certain value continues for a predetermined period, a proper decoding is judged impossible (step S 113 ), whereupon the sequence proceeds to a step S 114 .  
      The CPU-B  58  of the child device B 200  instructs a display control (video signal process) for a message “BAD RECEIVING STATE, PLEASE CHANGE SET POSITION OF CHILD DEVICE” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 114 ), thus requesting a movement to a location of a better reception state to the user. Also the CPU-B  58  of the child device B 200  wireless transmits child status information indicating a bad reception state to the patent device A 100  (step S 116 ).  
      Then, the CPU-A  38  of the parent device A 100 , in case the reception state is not improved, gives up the viewing by the user on the child device B 200  and executes a preparation for switching to a viewing by the user on the parent device A 100 . The CPU-A  38  of the parent device A 100  checks whether the digital tuner A 2  is in use (step S 117 ). If the digital tuner A 2  is in use, the sequence returns to the step S 111 , but, if the digital tuner A 2  is not in use, the sequence proceeds to a step S 118 .  
      The CPU-A  38  of the parent device A 100  instructs a display control (video signal process) for a message “CONTINUATION OF PROGRAM VIEWED WITH CHILD DEVICE TO BE VIEWED WITH PARENT DEVICE? YES: DECISION KEY, NO: CANCEL KEY” to the OSD processor A 9 , thereby displaying such message on the display A 10  (step S 118 ), thus requesting, to the user, a judgment whether to continue viewing, on the parent device A 100 , of the broadcast program which has been viewed with the child device B 200 .  
      Then the CPU-A  38  of the parent device A 100  discriminates the depressed key of the remote control  33  through the remote control interface  32 . In case the user depresses the decision cancel key (not shown), it is judged that the viewing is not continued in the parent device A 100  and the sequence returns to the step S 111 . In case the user depresses the decision key not shown), it is judged that the viewing is continued in the parent device A 100  and the sequence proceeds to a step S 111 .  
      In case the user depresses the decision key, the CPU-A  38  of the parent device A 100  executes a wireless transmission of parent device status information, indicating a termination of the transmission from the parent device A 100  to the child device B 200 , to the child device B 200  (step S 121 ), and terminates the transmission of the transport stream data to the child device B 200  (step S 122 ). Also, CPU-A  38  of the parent device A 100 , already knowing the broadcast channel (broadcast program) that has been viewed by the child device B 200 , sets the digital tuner A 2 , the video decoder A 6  and the audio decoder A 7  in a state capable of viewing the broadcast program in the parent device A 100 , and displays the broadcast channel (broadcast program), that has been viewed by the child device B 200 , on the display A 10  (step S 123 ), whereby a continued viewing on the parent device A 100  becomes possible.  
      On the other hand, the CPU-B  58  of the child device B 200  instructs a display control (video signal process) for a message “BAD RECEIVING STATUS. PLEASE USE PATENT DEVICE TO VIEW THIS PROGRAM” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 124 ), thus requesting a viewing on the parent device A 100  to the user.  
      In the present embodiment, as explained in the foregoing, while the user views a digital broadcasting in the child device B 200  utilizing the digital tuner B 12  of the parent device A 100 , the CPU-B  58  of the child device B 200  watches the receiving status of the child device B 200  (error rate of the transport stream data received from the patent device A 100 ), and, in case the receiving status becomes worse and the other digital tuner A 2  of the parent device A 100  is not in use, the CPU-A  38  of the parent device A 100  terminates the transmission of the transport stream data to the child device B 200  and sets the digital tuner A 2 , the video decoder A 6  and the audio decoder A 7  in a state capable of viewing the broadcast program in the parent device A 100 , whereby the user can automatically view, in continuation in the parent device A 100 , the broadcast program that has been viewed in the child device B 200 .  
     Second Embodiment  
       FIG. 4  is a block diagram showing a configuration of a parent/child television system constituting a second embodiment of the present invention.  
      The present embodiment is different from the foregoing first embodiment in that the child device B 200  is provided with a battery  70  and battery watching means  71  (watching means). Other components of the present embodiment are similar to those in the first embodiment ( FIG. 1 ), thus represented by corresponding numbers and are not explained further.  
      At first, there will be explained differences of the present embodiment from the first embodiment. The child device B 200  is battery drivable, and is rendered more widely movable by utilizing the battery  70  as a power source for the entire child device. A remainder charge of the battery  70  is constantly watched by the battery watching unit  71 , and is made available to the CPU-B  58  of the child device B 200 .  
      The CPU-A  38  of the parent device A 100  executes a process of a parent device side according to a program, in the flow charts shown in  FIGS. 5 and 6 , and the CPU-B  58  of the child device B 200  executes a process of a child device side according to a program, in the flow charts shown in  FIGS. 5 and 6 .  
      In the following there will be explained, with reference to flow charts shown in  FIGS. 5 and 6 , operations when a remainder charge of the battery becomes low while the user enjoys, in the parent/child television system of the present embodiment, a digital broadcasting in the child device B 200  by receiving transport stream data utilizing the digital tuner B 12  of the parent device A 100 .  
      Referring to  FIGS. 5 and 6 , the CPU-B  58  of the child device B 200  watches a battery remainder charge watched by a battery watching unit  71  (step S 131 ), and when the battery remainder charge is less than a limit for executing decoding processes in the video decoder B 44  and the audio decoder B 48  and for display in the display B 47  (step S 132 ), it transmits, by a wireless transmission, child device status information indicating a low battery remainder charge to the parent device A 100  (step S 133 ).  
      Then, the CPU-A  38  of the parent device A 100  gives up the viewing by the user on the child device B 200  and executes a preparation for switching to a viewing on the parent device A 100 . The CPU-A  38  of the parent device A 100  checks whether the digital tuner A 2  is in use (step S 134 ). If the digital tuner A 2  is in use, the sequence proceeds to a step S 144 , but, if the digital tuner A 2  is not in use, the sequence proceeds to a step S 36 . In case the digital tuner A 2  is not in use, the CPU-A  38  of the parent device A 100  executes a wireless transmission of parent device status information indicating that the digital tuner A 2  is usable, to the child device B 200  (step S 136 ).  
      In response, the CPU-B  58  of the child device B 200  instructs a display control (video signal process) for a message “BATTERY REMAINDER CHARGE SMALL. PARENT DEVICE USABLE FOR VIEWING THIS PROGRAM” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 137 ), thus requesting, to the user, a viewing on the parent device A 100 .  
      As the user is expected to come in front of the parent device A 100  in response to the message displayed on the display B 47 , the CPU-A  38  of the patent device A 100  instructs a display control (video signal process.) for a message “CONTINUATION OF PROGRAM VIEWED WITH CHILD DEVICE TO BE VIEWED WITH PARENT DEVICE? YES: DECISION KEY, NO: CANCEL KEY” to the OSD processor A 9 , thereby displaying such message on the display A 10  (step S 138 ), thus requesting, to the user, a judgment whether to continue viewing, on the parent device A 100 , of the broadcast program which has been viewed with the child device B 200 .  
      Then the CPU-A  38  of the parent device A 100  discriminates the depressed key of the remote control  33  through the remote control interface  32  (step S 139 ). In case the user depresses the decision cancel key, it is judged that the viewing is not continued in the parent device A 100  and the sequence proceeds to a step S 144 . In case the user depresses the decision key, it is judged that the viewing is continued in the parent device A 100  and the sequence proceeds to a step S 141 .  
      In case the user depresses the decision key, the CPU-A  38  of the parent device A 100  executes a wireless transmission of parent device status information, indicating a termination of the transmission from the parent device A 100  to the child device B 200 , to the child device B 200  (step S 141 ), and terminates the transmission of the transport stream data to the child device B 200  (step S 142 ). Also, CPU-A  38  of the parent device A 100  sets the digital tuner A 2 , the video decoder A 6  and the audio decoder A 7  in a state capable of viewing the broadcast program in the parent device A 100 , and displays the broadcast channel (broadcast program), that has been viewed by the child device B 200 , on the display A 10  (step S 143 ), whereby a continued viewing on the parent device A 100  becomes possible.  
      On the other hand, when the user depresses the decision cancel key, the CPU-B  58  of the child device B 200  instructs a display control (video signal process) for a message “BATTERY CHARGE REMAINDER SMALL. VIEWING PROGRAM WILL BE TRUNCATED” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 144 ), thus informing the user of the termination of viewing. The CPU-A  38  of the parent device A 100  executes a wireless transmission of parent device status information indicating termination of the transmission to the child device B 200  (step  146 ) and terminates the transmission of the transport stream data to the child device B 200  (step S 146 ).  
      In the present embodiment, as explained in the foregoing, while the user views a digital broadcasting in the child device B 200  utilizing the digital tuner B 12  of the parent device A 100 , the CPU-B  58  of the child device B 200  watches the battery remainder charge in the child device B 200 , and, in case the battery remainder charge becomes equal to or less than a threshold value and the other digital tuner A 2  of the parent device A 100  is not in use, the CPU-A  38  of the parent device A 100  terminates the transmission of the transport stream data to the child device B 200  and sets the digital tuner A 2 , the video decoder A 6  and the audio decoder A 7  in a state capable of viewing the broadcast program in the parent device A 100 , whereby the user can automatically view, in continuation in the parent device A 100 , the broadcast program that has been viewed in the child device B 200 .  
     Third Embodiment  
       FIGS. 7A and 7B  are block diagrams showing a configuration of a parent/child television system constituting a third embodiment of the present invention.  
      The present embodiment is different from the foregoing first embodiment in that the parent device A 100 ′ is provided with switches  4 ,  14 ,  15 , a hard disk drive (HDD) interface  16  and a HDD  17 , and the child device B 200  is provided with a battery  70  and battery watching means  71  (watching means). Other components of the present embodiment are similar to those in the first embodiment ( FIG. 1 ), thus represented by corresponding numbers and are not explained further.  
      At first, there will be explained differences of the present embodiment from the first embodiment, with reference to  FIGS. 7A and 7B . The HDD  17  of the parent device A 100  is used for recording and play the transport stream data received in the parent device A 100 ′. The HDD interface  16  controls the HDD  17  according to an instruction from the CPU-A  38 . The HDD may also be replaced by another large capacity memory enabling a high speed access such as MO, DVD-RAM or DVD-RW.  
      A switch  15  switches a data input to the HDD interface  16 , thereby selecting the broadcast transport data stream either from the demodulation/error correction circuit A 3  or from the demodulation/error correction circuit B 13 . Thus the HDD  17  can record the transport data stream selected by the demodulation/error correction circuit A 3  or by the demodulation/error correction circuit B 13 . The HDD  16  is capable of simultaneous recording and reproduction for one channel each. This enables so-called time-shift reproduction, by executing a recording and a reproduction simultaneously on a same broadcast program.  
      A switch  4  is provided between the demodulation/error correction circuit A 3  and the demultiplexer A 5 , thereby selecting the broadcast transport data stream either from the demodulation/error correction circuit A 3  or from the HDD interface  16  as the input to the demultiplexer A 5 . Thus the display A 10  and the speaker A 19  can reproduce, in addition to the broadcast transport stream data from the digital tuner A 2 , a broadcast transport stream data stored in the HDD  17 . At the reception of a digital broadcasting, the switch  4  is connected at the side of the the demodulation/error correction circuit A 3 .  
      A switch  14  is provided between the demodulation/error correction circuit B 13  and the transmission processor A 23 , thereby selecting the broadcast transport data stream either from the demodulation/error correction circuit B 13  or from the HDD interface  16  as the input to the transmission processor A 23 . Thus the child device B 200 ′ can reproduce, in addition to the broadcast transport stream data from the digital tuner B 12 , a broadcast transport stream data stored in the HDD  17 . At the reception of a digital broadcasting, the switch  14  is connected at the side of the the demodulation/error correction circuit B 13 .  
      The CPU-A  38  of the parent device A 100 ′ executes a process of a parent device side according to a program, in the flow charts shown in  FIG. 8  to  12 , and the CPU-B  58  of the child device B 200 ′ executes a process of a child device side according to a program, in the flow charts shown in  FIG. 8  to  12 .  
       FIG. 13  is a view showing an example of a menu image prepared by the OSD processor A 9  of the parent device A 100 .  
       FIG. 13  shows an image  202  displayed on the display A 10 , with messages “SET IMAGE QUALITY”, “SET AUDIO QUALITY” and “SET PROGRAM RECORDING”  221 - 223 , “WHEN TRANSMISSION TO CHILD DEVICE IS NOT AVAILABLE, PROGRAM RECORDING TO BE CONDUCTED”  224 , “YES (recording)”  231 , and “NO (no recording)”  232 .  
      In the following there will be explained, with reference to flow charts shown in  FIGS. 5 and 6  and a menu image shown in  FIG. 13 , operations when the reception state becomes worse or a remainder charge of the battery becomes low while the user enjoys, in the parent/child television system of the present embodiment, a digital broadcasting in the child device B 200  by receiving transport stream data utilizing the digital tuner B 12  of the parent device A 100 .  
      Referring to  FIGS. 8 and 12 , it is assumed that the user depresses, utilizing a cursor key (not shown) of the remote control  33 , the “YES (recording)” key  231  or the “NO (no recording)” key  232  and then the decision key (not shown). Key codes corresponding to these key operations are recognized by the CPU-A  38  of the parent device A 100 ′, which thus executes a setting of the user operation (step S 151 ).  
      After the setting, the user views a digital broadcast wave with the child device B 200 ′ (step S 152 ). In this state, the CPU-B  58  of the child device B 200 ′ watches an error rate of the transport stream data measured by the demodulation/error correction circuit D 42  and a battery remainder charge watched by a battery watching unit  71  (step S 153 ).  
      The CPU-B  58  of the child device B 200 ′ discriminates whether a state of the error rate exceeding a threshold value has reached a predetermined time or the battery remainder charge is less than a threshold value (step S 154 ), and, in case the state of the error rate exceeding the threshold value has reached a predetermined time or the battery remainder charge is less than the threshold value (reception incapable state), the sequence proceeds to a step S 156  but the sequence otherwise returns to the step S 153 .  
      In case of a reception incapable state, the CPU-B  58  of the child device B 200 ′, by a wireless transmission, transmits child device status information indicating a reception incapable state to the parent device A 100 ′ (step S 156 ). Then, the CPU-A  38  of the parent device A 100 ′ gives up the viewing by the user on the child device B 200 ′ and executes a preparation for program recording in the parent device A 100 ′. The CPU-A  38  of the parent device A 100 ′ checks a use state whether a recording by the digital tuner A 2  is currently executed on the HDD  17  (step S 157 ), and, in case the digital tuner A 2  is currently in use and the recording on the HDD  17  is not possible, the sequence proceeds to a step S 166 , but, in case the digital tuner A 2  is not in use and the recording on the HDD  17  is possible, the sequence proceeds to a step S 158 .  
      In case the digital tuner A 2  is not in use and the recording on the HDD  17  is possible, the CPU-A  38  of the parent device A 100 ′ discriminates the setting in the aforementioned step S 151  (step S 158 ), and sequence proceeds to a step s 159  in case of a setting “YES (recording)” or to a step s 166  in case of a setting “NO (no recording)”.  
      In case of a setting “YES (recording)”, the CPU-A  38  of the parent device A 100 ′ recognizes, by the SI information, an end time of the currently received broadcast program (step S 159 ). For recording, the CPU-A  38  of the parent device A 100 ′ shifts the switch  15  to the demodulation/error correction circuit B 13 , and records the transport stream data of the digital tuner B 12  on the HDD  17  until the end time obtained in the process of the step S 159  (step S 161 ). The CPU-A  38  of the parent device A 100 ′ executes a wireless transmission of parent device status information indicating that the recording is in progress, to the child device B 200 ′ (step S 162 ).  
      In response, the CPU-B  58  of the child device B 200 ′ instructs a display control (video signal process) for a message “RECEIVING IS NOT AVAILABLE. AUTOMATIC PROGRAM RECORDING BEING CONDUCTED WITH PARENT DEVICE” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 163 ), thus informing the user that the viewing of the digital broadcasting is not possible but it is recorded in the parent device A 100 ′. Thereafter the user can view a broadcast program which is interrupted during the viewing on the child device B 200 ′ and is being recorded, or a recorded broadcast program.  
      On the other hand, in case of a setting “NO (no recording)”, the CPU-A  38  of the parent device A 100 ′ executes a wireless transmission of parent device status information indicating that the recording is not executed, to the child device B 200 ′ (step S 166 ). In response, the CPU-B  58  of the child device B 200 ′ instructs a display control (video signal process) for a message “RECEIVING BEING NON-AVAILABLE. PROGRAM RECORDING IS NOT CONDUCTED” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 167 ), thus informing the user that the viewing of the digital broadcasting is not possible nor it is recorded in the parent device A 100 ′.  
      The foregoing is a process executed when the child device B 200 ′ becomes incapable of the reception. In the following there will be explained a process when the child device B 200 ′ becomes capable of the reception again.  
      The user may resolve the cause for disabled reception, for example by changing the location of the child device B 200 ′ or by charging the battery  70  of the child device B 200 ′ (step S 171 ). The CPU-B  58  of the child device B 200 ′ watches an error rate of the transport stream data measured by the demodulation/error correction circuit D 42  and a battery remainder charge watched by a battery watching unit  71  (step S 172 ).  
      The CPU-B  58  of the child device B 200 ′ discriminates whether the error rate does not exceed the threshold value and the battery remainder charge is larger than the threshold value (step S 173 ), and, in case the error rate does not exceed the threshold value and the battery remainder charge is larger than the threshold value (reception capable state), the sequence proceeds to a step S 174  but otherwise (reception incapable state) the sequence returns to the step S 172 .  
      In case a reception capable state is reached, the CPU-B  58  of the child device B 200 ′, by a wireless transmission, transmits child device status information indicating a reception capable state to the parent device A 100 ′ (step S 174 ), and restarts the reception of the transport stream data in the child device. B 200 ′ (step S 176 ). Then, the CPU-A  38  of the parent device A 100 ′ instructs a display control (video signal process) for a message “PROGRAM VIEWING AVAILABLE WITH CHILD DEVICE” to the OSD processor A 9 , thereby displaying such message on the display A 10  (step S 177 ), thus informing the user who might have given up the viewing on the child device B 200 ′ and might be viewing on the parent device A 100 ′ that the viewing on the child device B 200 ′ is available again.  
      Then the CPU-A  38  of the parent device A 100 ′ discriminates whether the broadcast program which was interrupted during the viewing by the user on the child device B 200 ′ is being recorded or has been recorded (step S 178 ), and, the sequence proceeds to a step S 179  in case the broadcast program which was interrupted during the viewing by the user on the child device B 200 ′ is being recorded or has been recorded, but the sequence proceeds to a step S 88  in case the broadcast program which was interrupted during the viewing by the user on the child device B 200 ′ is not being recorded nor has been recorded.  
      In case the broadcast program interrupted during the viewing is being recorded or has been recorded, the CPU-A  38  of the parent device A 100 ′ checks whether the HDD  17  is not used by the demultiplexer A 5  and is available for reproduction (step S 179 ). Then the sequence proceeds to a step S 181  in case the HDD  17  is not used by the demultiplexer A 5  and is available for reproduction but to a step S 188  in case the HDD  17  is used by the demultiplexer A 5  and is not available for reproduction.  
      In case the the HDD  17  is not used by the demultiplexer A 5  and is available for reproduction, the CPU-A  38  of the parent device A 100 ′ executes a wireless transmission of parent device status information indicating that the reproduction is possible, to the child device B 200 ′ (step S 181 ). In response, the CPU-B  58  of the child device B 200 ′ instructs a display control (video signal process) for a message “PLAY FROM INTERRUPTED POSITION WITH CHILD DEVICE. SELECT DECISION KEY TO START PLAY” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 182 ), thus informing the user of a viewing capable state where the viewing in the child device is reopened and the interrupted and recorded broadcast program can be reproduced by a depression of the decision key of the child device B 200 ′.  
      Then the CPU-B  58  of the child device B 200 ′ discriminates a key input by the user on the child device B 200 ′ (step S 183 ), and the sequence proceeds to a step S 184  in case of a depression of the decision key indicating a start of reproduction in the child device B 200 ′, or to a step S 189  in case the decision key is not depressed, where the reproduction is not executed since the user wishes to continue current viewing of a broadcast program or does not wish the reproduction.  
      In case the decision key is depressed, the CPU-B  58  of the child device B 200 ′ executes a wireless transmission of child device status information indicating a completion of preparation for reproduction to the parent device A 100 ′. In response, the CPU-A  38  of the parent device A 100 ′ shifts the switch  14  to the HDD  16 , thereby transmitting a reproduced transport stream data to the child device B 200 ′ (step S 186 ). Thus the user can view the reproduced broadcast program on the child device B 200 ′ (step S 187 ).  
      On the other hand, in case the broadcast program interrupted during the viewing is not being recorded nor has been recorded, the CPU-A  38  of the child device A 100 ′ executes a wireless transmission of parent device status information indicating that the reproduction is not possible to the child device B 200 ′ (step S 188 ). In response, the CPU-B  58  of the child device B 200 ′ instructs a display control (video signal process) for a message “BROADCASTED PROGRAM CAN BE REVIEWED WITH CHILD DEVICE” to the OSD processor B 46 , thereby displaying such message on the display B 47  (step S 189 ), thus informing the user that the viewing of the digital broadcasting is possible in the child device B 200 ′.  
      In the present embodiment, as explained in the foregoing, while the user views a digital broadcasting in the child device B 200  utilizing the digital tuner B 12  of the parent device A 100 , the CPU-B  58  of the child device B 200 ′ watches the reception state of the child device B 200 ′ and the battery remainder charge in the child device B 200 ′, and, in case the reception state becomes worse or the battery remainder charge becomes equal to or less than a threshold value and the other digital tuner A 2  of the parent device A 100 ′ is not in use and available for recording, the CPU-A  38  of the parent device A 100 ′ starts a recording on the HDD  17 , whereby the user can automatically record, in the parent device B 200 ′, the broadcast program that has been viewed in the child device B 200 ′.  
      Also it is possible not to record a broadcast program not worth recording by rendering the remote control  33  capable of selecting whether or not to execute an automatic recording. Also in case the child device B 200 ′ re-starts reception from the patent device A 100 ′ and if the HDD  17  of the patent device A 100 ′ is available for reproduction, the user can view a continuation of the broadcast program, that has been interrupted, in the child device B 200 ′ by reproduction.  
     Fourth Embodiment  
      The present embodiment is different from the foregoing third embodiment in that the parent device A 100 ′ discriminates a reception capable state of the child device B 200 ′ by receiving therefrom a periodical status. Other components of the present embodiment are similar to those in the first embodiment ( FIG. 1 ), thus represented by corresponding numbers and are not explained further.  
      The CPU-A  38  (control means) of the parent device A 100 ′ executes a process of a parent device side according to a program, in the flow charts shown in  FIG. 14  to  16 , and the CPU-B  58  (informing means) of the child device B 200 ′ executes a process of a child device side according to a program, in the flow charts shown in  FIG. 14  to  16 .  
      In the following there will be explained, with reference to flow charts shown in FIGS.  14  to  16  and a menu image shown in  FIG. 13 , differences from the third embodiment in the operations of the parent/child television system of the present invention.  
      Referring to FIGS.  14  to  16 , the user sets [YES] or [NO] in a message “WHEN TRANSMISSION TO CHILD DEVICE IS NOT AVAILABLE, PROGRAM RECORDING TO BE CONDUCTED?” on the menu image of the parent device A 100 ′ shown in  FIG. 13  (step S 151 ). After the setting, the user views a digital broadcasting with the child device B 200 ′ (step S 152 ). In this state, the CPU-B  58  of the child device B 200 ′ executes a wireless transmission, to the parent device A 100 ′, of child device status information indicating a normal reception periodically at a time interval, for example a vertical synchronization cycle (S 211 ).  
      The CPU-A  38  of the patent device A 100 ′ discriminates whether the child device status information indicating the normal reception is periodically received from the child device B 200 ′ (step S 212 ). In case the child device status information indicating the normal reception is periodically received, the sequence returns to the step S 211  and the CPU-A  38  of the patent device A 100 ′ continues reception. In case a failure in the reception of the child device status information indicating the normal reception occurs a certain number of times, the CPU-A  38  of the patent device A 100 ′ judges that the child device B 200 ′ is incapable of reception (step S 214 ), thus giving up the viewing by the user in the child device B 200 ′ and executes a preparation for recording in the parent device A 100 ′.  
      The CPU-A  38  of the parent device A 100 ′ checks a use state whether a recording by the digital tuner A 2  is currently executed on the HDD  17  (step S 157 ), and, in case the digital tuner A 2  is currently in use and the recording is not possible, the sequence proceeds to a step S 216 , but, in case the digital tuner A 2  is not in use and the recording is possible, the sequence proceeds to a step S 158 .  
      In case the digital tuner A 2  is not in use and the recording is possible, the CPU-A  38  of the parent device A 100 ′ discriminates the setting in the aforementioned step S 151  (step S 158 ), and sequence proceeds to a step S 159  in case of a setting “YES (recording)” or to a step S 216  in case of a setting “NO (no recording)”.  
      In case of a setting “YES (recording)”, the CPU-A  38  of the parent device A 100 ′ recognizes, by the SI information, an end time of the currently received broadcast program (step S 159 ). For recording, the CPU-A  38  of the parent device A 100 ′ shifts the switch  15  to the demodulation/error correction circuit B 13 , and records the transport stream data of the digital tuner B 12  on the HDD  17  until the end time obtained in the process of the step S 159  (step S 161 ).  
      The foregoing is a process executed when the child device B 200 ′ becomes incapable of the reception. In the following there will be explained a process when the child device B 200 ′ becomes capable of the reception again.  
      The user may resolve the cause for disabled reception, for example by changing the location of the child device B 200 ′ or by charging the battery  70  of the child device B 200 ′ thereby improving the reception state of the child device B 200 ′ (step S 216 ). The CPU-B  58  of the child device B 200 ′, upon re-starting the reception from the parent device A 100 ′, periodically transmits child device status information indicating a normal reception to the parent device A 100 ′ (step S 217 ).  
      The CPU-A  38  of the patent device A 100 ′ discriminates-whether the child device status information indicating the normal reception is periodically received from the child device B 200 ′ (step S 218 ). In case the child device status information indicating the normal reception is not periodically received, the sequence returns to the step S 218  and the CPU-A  38  of the patent device A 100 ′ continues reception. In case the child device status information indicating the normal reception can be received, the sequence proceeds to a step S 221 .  
      The CPU-A  38  of the parent device A 100 ′, judging that the child device B 200 ′ is capable of reception (step S 221 ), instructs a display control (video signal process) for a message “PROGRAM VIEWING AVAILABLE WITH CHILD DEVICE” to the OSD processor A 9 , thereby displaying such message on the display A 10  (step S 177 ). The process thereafter is same as the process after the step S 178  of the third embodiment shown in  FIG. 11 , and will not therefore be explained.  
      In the present embodiment, as explained in the foregoing, even in case the child device B 200 ′ suddenly becomes incapable of receiving the video stream data from the patent device A 100 ′ and does not have an enough time for sending the status indicating a reception incapable state to the patent device A 100 ′, the CPU-A  38  of the child device A 100 ′ recognizes a reception incapable state of the child device B 200 ′ when the status indicating the normal reception, periodically transmitted from the child device B 200 ′ to the parent device A 100 ′, is not transmitted from the child device B 200 ′, and starts the preparation for recording in the parent device A 100 ′, whereby the automatic recording is rendered possible in the parent device A 100 ′.  
     Other Embodiments  
      The foregoing first embodiment has shown a case where the broadcast program that has been displayed in the child device is displayed in the parent device when the reception state of the child device becomes worse, but such configuration is not restrictive and the user may be allowed to select either to display the broadcast program, that has been displayed in the child device, in the parent device, or to record the broadcast program, that has been displayed in the child device, in the parent device.  
      The foregoing second embodiment has shown a case where the broadcast program that has been displayed in the child device is displayed in the parent device when the remainder charge of the battery of the child device becomes equal to or less than the threshold value, but such configuration is not restrictive and the user may be allowed to select either to display the broadcast program, that has been displayed in the child device, in the parent device, or to record the broadcast program, that has been displayed in the child device, in the parent device.  
      The foregoing third embodiment has shown a case where the broadcast program that has been displayed in the child device is recorded in the parent device when the reception state of the child device becomes worse or the remainder charge of the battery of the child device becomes equal to or less than the threshold value, but such configuration is not restrictive and the user may be allowed to select either to record the broadcast program, that has been displayed in the child device, in the parent device, or to display the broadcast program, that has been displayed in the child device, in the parent device.  
      The foregoing fourth embodiment has shown a case where the broadcast program that has been displayed in the child device is recorded in the parent device when the status information indicating the normal reception is not transmitted from the child device to the parent device, but such configuration is not restrictive and the user may be allowed to select either to record the broadcast program, that has been displayed in the child device, in the parent device, or to display the broadcast program, that has been displayed in the child device, in the parent device.  
      The foregoing first to fourth embodiments have shown a case where the parent device and the child device execute wireless communication, but such configuration is not restrictive and the parent device and the child device may execute wired communication.  
      The present invention can also be realized by supplying a computer or a CPU with a program (corresponding to flow charts shown in FIGS.  2  to  3 ,  5  to  6 ,  8  to  12 , and  14  to  16 ) of a software realizing the functions of the aforementioned embodiments and reading and executing such supplied program by the computer or the CPU.  
      In such case, the program may be supplied directly from a recording medium storing such program, or supplied by a downloading from another unillustrated computer or a database connected to the internet, a commercial network- or a local area network.  
      The program may assume a form of object codes, program codes executed by an interpreter, or script data to be supplied to an OS (operating system).  
      Also the present invention can be realized by supplying a computer or a CPU with a program of a software realizing the functions of the aforementioned embodiments and reading and executing such supplied program by the computer or the CPU.  
      In such case, the program codes themselves read from the memory medium realize the functions of the aforementioned embodiments, and the memory medium storing the program codes constitutes the present invention.  
      The memory medium storing the program codes can be, for example, a ROM, a RAM, an NV-RAM, a floppy disk (trade name), a hard disk, an optical disk (trade name), a magnetooptical disk, a CD-ROM, an MO, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, a DVD-RW, a DVD+RW, a magnetic tape or a non-volatile memory card.  
      The functions of the aforementioned embodiments can be realized, not only in a case of executing the read program codes by the computer, but also in a case where an OS or the like functioning on the computer executes all the actual processes or a part thereof under the instruction of the program codes.  
      This application claims priority from Japanese Patent Application No. 2003-410610 filed on Dec. 9, 2003, which is hereby incorporated by reference herein.