Abstract:
A digital television receiver comprises first program rewriting unit for downloading a program sent by broadcasting to rewrite the contents of a first non-volatile memory, an electrically rewritable second non-volatile memory storing identification information indicating whether the program has been normally rewritten by the program rewriting unit or the program has not been normally rewritten by the shutoff of the power during the rewriting, and second program rewriting unit for checking the identification information when a control portion in the receiver is activated, and downloading the program sent by broadcasting again to rewrite the contents of the first non-volatile memory when it is detected that the program has not been normally rewritten.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a digital television receiver. 
     2. Description of the Prior Art 
     In a multi-channel digital satellite broadcasting (CS broadcasting) system using CS (Communication Satellite) which has been started in recent years, a lot of (for example, 100 or more) channels are prepared, and a lot of programs are provided. 
     In such broadcasting, there are functions which have not been so far seen. For example, guide information relating to programs which are being currently broadcast and programs which will be broadcast in the future, together with original program data, are transmitted at predetermined time intervals, and a viewer can select and view the program on the basis of the program guide (electronic program guide [EPG]) information. 
     In such a digital television receiver, a ROM whose contents cannot be generally rewritten has been employed as a program ROM. For convenience of a CS broadcasting form, it is prescribed that a rewritabie ROM is mounted as a program ROM (hereinafter referred to as a program memory) as a standard in order to change the specification thereof and improve the function thereof. 
     When the rewritable program memory is mounted on the digital television receiver, it is possible to rewrite the contents of the program memory by sending a rewriting program by a broadcast wave. 
     When the power is shut off on the basis of a power failure or the power is shut off on the basis of a user operation while the contents of the program memory are being rewritten utilizing the broadcast wave, however, a program for a control portion in the receiver is not normally rewritten. Accordingly, the contents of the program memory must be rewritten by a repairing person. 
     When the control portion is reactivated upon normal completion of the rewiring of the program, the structures of data stored in a non-volatile data area change depending on the program which has been rewritten. Therefore, the data structures must be manually reset. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a digital television receiver in which in a case where a program is not normally rewritten by the shutoff of the power based on a power failure or the shutoff of the power based on a user operation while the contents of a program memory are being rewritten utilizing a broadcast wave, the program is automatically rewritten when the power is returned. 
     A television receiver according to the present invention is characterized by comprising a control portion for controlling the whole of the receiver; an electrically rewritabie first non-volatile memory storing an execution program for the control portion; first program rewriting means for downloading a program sent by broadcasting to rewrite the contents of the first non-volatile memory; an electrically rewritable second non-volatile memory storing identification information indicating whether the program has been normally rewritten by the program rewriting means or the program has not been normally rewritten by the shutoff of the power during the rewriting; second program rewriting means for checking the identification information when the control portion is activated, and downloading the program sent by broadcasting again to rewrite the contents of the first non-volatile memory when it is detected that the program has not been normally rewritten; and means for changing, when the program has been normally rewritten by the second program rewriting means, the identification information into information indicating that the program has been normally rewritten. 
     It is preferable that there is provided means for initializing the second non-volatile memory when the control portion is first activated after the program is normally rewritten. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the configuration of a digital television receiver; 
     FIG. 2 is a flow chart showing the procedure for processing performed by a system controller  20  when download is started; 
     FIG. 3 is a flow chart showing the procedure for processing performed by the system controller  20  when the system controller  20  is activated; and 
     FIG. 4 is a schematic view showing the contents of a program memory  21 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings , an embodiment of the present invention will be described. 
     FIG. 1 illustrates the configuration of a digital television receiver having the function of receiving CS digital broadcasting. 
     A CS broadcast wave utilizing communication satellite (CS) is sent to a CS tuner  2  through a CS antenna  1 , where it is subjected to high-frequency processing and demodulation. An output from the CS tuner  2  is sent to a DEMUX circuit  3 , where packets are demodulated. 
     In the DEMUX circuit  3 , the packets are classified into MPEG (Motion Picture Expert Group) data and attachment information such as program guide information. The MPEG data obtained by the classification in the DEMUX circuit  3  is sent to an audio/video decoder  4 . The attachment information such as the program guide information obtained by the classification in the DEMUX circuit  3  is sent to a system controller  20 . 
     The system controller  20  comprises a program memory  21  composed of a flash memory, a non-volatile memory  22  composed of an EEPROM (Electrically Erasable and Programmable ROM), and a volatile memory  23  composed of a RAM in this example. The program memory  21  stores a program for the system controller  20 . The non-volatile memory  22  stores a download flag, described later, and various types of data. The volatile memory  23  stores download data, described later, and the other necessary data. 
     The system controller  20  causes the attachment information sent from the DEMUX circuit  3  to be stored in the volatile memory  23 . A remote control signal from a remote control transmitter  12  is inputted to the system controller  20  through a remote control receiver  13 . 
     The system controller  20  sends information for channel selection, for example, to the tuner  2  and the DEMUX circuit  3 . The system controller  20  sends to an OSD (On-Screen Display) circuit  14  an OSD control signal for on-screen displaying a program guide for CS broadcasting, various types of setting screens for CS broadcasting, and so forth on a CRT (Cathode-Ray Tube)  8 . The OSD circuit  14  produces display data representing a program guide or the like, and sends the display data to a multiplexer (a synthesis circuit)  6 . 
     The audio/video decoder  4  demodulates MPEG data sent from the DEMUX circuit  3 . A video signal obtained by the audio/video decoder  4  is sent to the multiplexer  6  through a video processing circuit  5 . The multiplexer  6  superimposes the display data sent from the OSD circuit  14  on video data outputted from the video processing circuit  5 , and sends data after the superimposition to a video output circuit  7 . A video signal outputted from the video output circuit  7  is sent to the CRT  8 . 
     An audio signal obtained by the audio/video decoder  4  is sent to a speaker  11  through an audio processing circuit  9  and an audio output circuit  10 . 
     In the present embodiment, rewriting program (hereinafter referred to as download data) for the program memory  21  is also sent out by broadcasting. When the download data is being sent out by broadcasting, the system controller  20  acquires a download control table (DCT) on the basis of the attachment information. The download control table includes a maker ID, a model ID, and a version ID. 
     The system controller  20  judges whether or not the maker ID and the model ID are adapted to the digital television receiver, and judges, when they are adapted to the receiver, whether or not the version ID is newer than that of a program currently carried. When the version ID is newer than that of the program currently carried, download is started. 
     When the version ID is newer than that of the program currently carried, the system controller  20  may indicate that the download can be started and cause a user to enter an instruction to perform the download. 
     FIG. 2 shows the procedure for processing performed by the system controller  20  when the download is started. 
     When the download of the rewriting program is started, binary data representing the rewriting program which is to be stored in the program memory  21  is stored in the volatile memory  23  (step  1 ). Generally, time required to download the rewritable program is approximately 10 minutes. 
     When the download is completed, a download flag F which is to be stored in the non-volatile memory  22  is set to “rewriting” (step  2 ). For example, the download flag F is composed of two bits, and stores three states, i.e., clear “00”, rewriting “01”, and initializing “ 11 ”. 
     The contents of the program memory  21  are then erased (step  3 ). Thereafter, program rewriting processing is performed (step  4 ). That is, the data representing the rewriting program which has been stored in the volatile memory  23  at the foregoing step  1  are successively written into the program memory  21 . 
     When the writing of the rewriting program into the program memory  21  is terminated, the download flag F is set to “initializing” (step  5 ). Thereafter, the system controller  20  is reactivated. 
     When the power is shut off while the processing at the foregoing step  1  is being performed, that is, the rewriting program is being downloaded, the download data which have been stored in the volatile memory  23  until the power is shut off are erased. In this case, the contents of the program memory  21  are not rewritten at all. After the power is returned, therefore, the digital television receiver is normally operated as a digital television broadcasting receiver before the shutoff of the power. 
     When the power is shut off in a time period elapsed from the time when the contents of the program memory  21  are erased at the foregoing step  3  until the writing of the rewriting program into the program memory  21  is terminated, that is, in a time period elapsed from the time when the download flag F is set to “rewriting” until the download flag F is set to “initializing”, the contents of the program memory  21  become incomplete. When no processing is performed when the power is returned (when the system controller  20  is activated), therefore, the digital television receiver is not normally operated as a digital television broadcasting receiver. In the present embodiment, the following processing is performed when the system controller  20  is activated. 
     FIG. 3 shows the procedure for processing performed by the system controller  20  when the system controller  20  is activated. 
     When the system controller  20  is activated, it is judged whether or not the download flag F is set to “rewriting” (step  11 ). When the download flag F is not set to “rewriting”, it is judged whether or not the download flag F is set to “initializing” (step  16 ). When the download flag F is not set to “initializing”, that is, the download flag F is in a cleared condition, ordinary processing is performed. 
     When it is judged at the step  16  that the download flag F is set to “initializing”, it is judged that the current activation is the first activation after the program is normally rewritten. Accordingly, initialization processing of the non-volatile memory  22  is performed (step  17 ). Thereafter, ordinary processing is performed. In the initialization processing of the non-volatile memory  22 , the download flag F is cleared. 
     When the download flag F is set to “rewriting” at the foregoing step  11 , it is judged that the power is shut off in a time period elapsed from the time when the contents of the program memory  21  are erased at the step  3  shown in FIG. 2 until the writing of the rewriting program into the program memory  21  is terminated. Accordingly, the rewriting program is downloaded again (step  12 ). That is, the binary data representing the rewriting program which is to be stored in the program memory  21  is stored in the volatile memory  23 . 
     When the download is completed, the contents of the program memory  21  are erased (step  13 ). Thereafter, program rewriting processing is performed (step  14 ). That is, the data representing the rewriting program which have been stored in the volatile memory  23  at the foregoing step  12  are successively written into the program memory  21 . 
     When the writing of the rewriting program into the program memory  21  is terminated, the download flag F is set to “initializing” (step  15 ). Thereafter, the system controller  20  is reactivated. When the system controller  20  is reactivated, the answer is in the negative at the step  11 , and the answer is in the affirmative at the step  16 . After the initialization processing of the non-volatile memory  22  is performed (step  17 ), ordinary processing is performed. 
     The processing at the steps  11  to  14  shown in FIG. 3 must be performed even when the power is returned after the program is normally rewritten. Therefore, a program for performing the processing at the steps  11  to  14  is not erased at the step  3  shown in FIG. 2 or the step  13  shown in FIG.  3 . 
     The program memory  21  comprises an area E 1  for storing a program for performing the processing at the steps  11  to  14  and an area E 2  for storing the other programs, as shown in FIG.  4 . At the step  3  or the step  13 , only the contents of the area E 2  are erased. 
     According to the present embodiment, when the program is not normally rewritten by the shutoff of the power based on a power failure or the shutoff of the power based on a user operation while the program memory is being rewritten, the program is automatically rewritten when the power is returned. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.