JP2685915B2 - Pay broadcast receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a pay broadcast receiving apparatus that mutes the audio of pay program information that is scrambled and transmitted from the transmitting side by judging whether or not it is viewable. .

(Prior Art) In a subscribing TV system, pay program information is encrypted according to a predetermined scramble law in order to prevent non-contracted subscribers from watching pay programs. The contracting subscriber obtains the descrambling key information from the transmitting side by specifying the contracting party's terminal information (for example, contract program information, terminal address information, fee payment information, etc.) and performs descrambling (plain culture). be able to. Since the non-contracted subscriber cannot receive the key information, the scramble information cannot be descrambled to normal information. The key information is regularly updated in order to prevent the scramble law from being decrypted maliciously.

By the way, when the pay program information is audio information or video and audio information, unless the scramble applied to the audio information is properly descrambled, a loud noise may occur and the speaker may be destroyed. Therefore, each terminal is provided with a viewing availability determination circuit that determines availability of viewing by a terminal memory that registers the terminal information, and when the determination signal from this circuit denies viewing, the audio signal is muted. It has become.

FIG. 5 shows a conventional pay broadcast receiving apparatus provided with the mute circuit.

In FIG. 5, 1 is a transmitter, and 2 is a receiver.

The transmitter 1 corresponds to one broadcasting station and supplies program information to the scramble circuit 3. The scramble circuit 3 scrambles the pay program information and sends the normal program information to the transmission line 4 as it is. The transmission device 1 uses the same transmission path as the program information or another transmission path 5 to 9
Scramble ON / OFF information indicating whether or not the program information being transmitted is scrambled, descrambling key information, key update timing information indicating whether or not the key information is updated, contract program indicating a contract program The contract information indicating whether or not information and fees have been paid is transmitted.

The receiving device 2 includes a channel selecting circuit 11 for selecting the transmitting device 1, a switch 12 for switching and connecting the transmission lines 4 to 9 according to a channel selection signal from the channel selecting circuit 11, a viewability judging circuit 13, and a program from the transmission line 4. A descramble circuit 14 that descrambles information, an AND circuit 15 that supplies scramble ON / OFF information and key information to the descramble circuit 14 when viewing, and a mute that mutes signals from the key gate circuit 16 and the descramble circuit 14, respectively. Circuit 17
And a mute control circuit 18 for controlling the mute circuit 17.

 The operation of the above configuration is as follows.

The transmitter 1 regularly updates the key information, the contract program information, and the contract information, which are transmitted before the time of actually using for descrambling. The viewability determination circuit 13 inputs contract program information, contract information (hereinafter, these two pieces of information are collectively referred to as contract information), and key update timing information,
The contract information is collated with each other to determine whether or not viewing is possible.

When the above judgment result is the logic level (logic “1”) indicating “viewable”, it means that the program is contracted and the fee has been paid, whereby the AND circuit 15 is opened and the key is locked. The gate circuit 16 extracts the key information, and the mute control circuit 18 outputs a signal for turning off the mute circuit 17. In this way, the normal descramble program information is viewed.

When the determination result of the viewability determination circuit 13 is the logic level (logic “0”) indicating “viewability”, there is no program contract, so the AND circuit 15 is closed and the key gate circuit 16 extracts the key information. Can not. Further, the mute control circuit 18 outputs a signal for turning on the mute circuit 17. In this way, the signal due to abnormal descrambling is muted by the mute circuit 17. The above determination operation is performed every time the key update timing information is received.

In the above case, the mute ON / OFF signal is e, scrambled
If the ON / OFF signal is a and the result of the viewing availability is b, then e =
It can be represented by a logical expression of a and b. b is "no viewing"
Means

In the case of normal program information that is not descrambled, the output of the viewability determination circuit 13 becomes "viewable", and the scramble OFF signal is the descramble circuit 1.
By being supplied to 4, the descramble circuit 14 passes the information as it is, and the mute circuit 17 also passes the signal.

In the above case, the judging operation of the viewability judging circuit 13 may be delayed, and although the correct key information cannot be obtained, inconvenience may occur in that mute is not applied.

FIG. 6 is a time chart showing the determination operation at the time of channel switching in detail. (A) shows program information in which the channel is switched, (b) is a channel switching timing signal,
(C) is key update timing information, (d) to (f) are key information and contract information, d is for transmission, (e) is for viewing / listening availability determination, and (f) is for descramble. . (G) shows the viewability judgment output, and (h) and (i) show mute ON.
/ OFF signal, respectively.

In FIG. 6, when the channel A is switched to the channel B, first, the channel switching timing signal (b) exhibits the pulse P ₁ . This pulse P ₁ is supplied to the mute circuit 17 via the mute control circuit 18,
Mute 17 This is to eliminate this noise because instantaneous noise is generated regardless of ON / OFF of scrambling due to instantaneous interruption and discontinuity of the signal due to channel switching.

The transmitter 1 transmits the key information one cycle before. For example, the program information of the cycle in which the key information K _A2 and the contract information A ₂ are transmitted is the key information K _A1 transmitted in the immediately preceding cycle. Can be successfully descrambled by. In this case, the key information
It is determined whether or not K _A1 is acquired for descrambling by determining the contract information A ₁ received at the same time.

Now consider the case where the channels are switched. time
At t ₁ , the information stored as the key information is K _A2 , and the received program information cannot be decrypted with such key information, so the update timing signal P ₂ appears as shown in (g). During the period A up to, the viewing approval / disapproval determination signal is set to “viewing / disapproval”. As a result, the mute ON / OFF signal is "ON".
The mute circuit 17 is muted.

Next, when the update timing signal P ₂ is received, descrambling is performed based on the key information K _B0 stored in the previous cycle (when switching channels), the mute ON / OFF signal is turned “OFF”, and the mute circuit 17 , Pass the descramble signal without muting.

If the mute ON / OFF signal in this case is expressed by a logical expression, the channel switching timing signal is c, and e = a · b + c
Becomes

If, after t ₁ , K _B0 and B ₀ cannot be stored during the first update, the terminal information memory holds the key information K _{A3 of} channel A that was stored before the channel switching, and by this, It will be descrambled. In such cases, normal descrambling will not occur.

(Problems to be Solved by the Invention) A conventional pay broadcast receiving apparatus sometimes performs descrambling even when correct key information is not obtained at the time of channel switching, and there is a disadvantage that normal descrambling is not performed. It was

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems and to provide a pay broadcast receiving apparatus capable of receiving information without waste even if correct key information cannot be obtained when channel switching is performed.

[Structure of the Invention] (Means for Solving the Problems) The pay broadcast receiving apparatus according to the first invention is transmission program information, scramble ON / OFF information indicating whether or not the transmission program information is scrambled, and scrambled. Means for receiving key information for descrambling the transmitted program information, key update timing information indicating a timing at which the key information is updated, and contract information for obtaining the key information. And a descrambling means for descrambling the scrambled transmission program information based on the key information, a mute means for selectively muting the output of the descrambling means, and the contract information for checking the viewing availability. The channel is switched when the scramble ON / OFF information indicates scrambling “ON”. If the channel switching timing signal indicating the bets is inputted, characterized by comprising a muting control means for stopping the muting operation of the muting means by said key update timing signal input to the second.

Also, the pay broadcast receiving device of the second invention is transmission program information, scramble ON / OFF information indicating whether or not the transmission program information is scrambled, and a key for descrambling the scrambled transmission program information. Information, a means for indicating the timing at which the key information is updated, key update timing information sent at every predetermined period, and contract information for obtaining the key information, and the scrambled transmission program information as the key. Descrambling means for descrambling based on information, mute means for selectively muting the output of the descrambling means, and when the channel is switched when the scrambling ON / OFF information indicates scrambling "ON" Mute control means for mute operation of the mute means and the contract information are collated with each other to determine whether or not viewing is possible. And mute control means for determining whether or not the contract information that can be collated is received before the first key update timing signal is input after the channel is switched, and the mute control means is the determination means. Is received, the mute operation is stopped at a timing corresponding to the first key update timing signal.

(Operation) According to such a configuration, in the first invention, after the mute period determined by the output of the viewability determination circuit,
The mute pulse output from the mute control signal generating circuit mutes until the second key update when key information is obtained, and the mute period does not exceed. In the second aspect of the invention, the output of the viewability determination circuit is set to "viewable" until the update period when the key information is obtained. Therefore, when the key information is obtained in the period immediately after the channel switching and when it is not obtained. It is possible to determine the shortest mute period according to

(Example) Hereinafter, the present invention will be described in detail with reference to an illustrated example.

FIG. 1 is a block diagram showing an embodiment of a pay broadcast receiving apparatus according to the present invention.

In FIG. 1, 24 is a switch for selectively selecting and outputting a set of information (program information, scramble ON / OFF information, key information, key update timing information, contract information) from a plurality of transmitters (not shown), 23 Is a channel selection circuit for controlling the switch 24.

Program information is sent to the descramble circuit 28 via the switch 24.
The de-scrambled output supplied to the mute circuit
Entered in 32.

The two contract information (program contract information, contract information) and the key update timing information are respectively input to the viewability judging circuit 25, and the above two contract information are compared and judged at the timing of the key update timing information. ing. The viewability determination circuit 25 derives a determination output indicating “viewability” when the contract information is compared with each other, and a determination output indicating “viewability” when the contract information is not compared.

The key information is supplied to the key gate circuit 26, and scrambling is turned on.
The / OFF information is supplied to the AND circuit 27. Key gate circuit 26
Is gate-controlled by the viewability determination output, and when the output is "viewable", correct key information is extracted. The AND circuit 27 is gate-controlled by the viewability determination output, and enables the descramble circuit 28 when the scramble ON / OFF information indicates ON (scramble).

Therefore, the mute control signal generation circuit 31 is a circuit provided by this embodiment, and receives the key update timing information and the channel switching timing signal from the channel selection circuit 23. The mute control signal generation circuit 31
After inputting the channel switching timing signal, a mute pulse is output while counting two key update timing signals.
The output 31a of the mute control signal generation circuit 31 becomes an AND output 30a with the scramble ON / OFF information in the AND circuit 30 and is input to the mute control circuit 29.

The mute control circuit 29 controls the mute circuit 32 by forming scramble ON / OFF information, viewing permission judgment output, channel switching timing signal and mute ON / OFF signal by the signal 30a.

The operation of the pay broadcast receiving apparatus will be described with reference to the time chart of FIG.

The signals (a) to (f) shown in FIG. 2 are the same as in FIG. The signal (g) is the viewing availability determination output, and (h) is the signal 31.
a and (i) indicate a mute ON / OFF signal.

Now, when the channel is switched at time t ₁ , the pulse P _{1 of the} channel switching timing signal (b) is _first supplied from the channel selection circuit 23 to the mute control circuit 29 and the mute control signal generation circuit 31. The pulse P ₁ is input to the mute control circuit 29 so that the scramble ON / O signal is output.
It becomes a signal for muting the mute circuit 32 regardless of the FF signal, and eliminates noise generated at the time of channel switching.

Then, the viewing determination circuit 25 derives a determination output indicating between "viewing whether" the first update timing signal P ₂ from the time t ₁ is received. This judgment output is output from the mute control circuit 29.
The logical product outputs a and b are formed with the scramble ON / OFF signal, and the mute ON / OFF signal is generated by the mute circuit 32.
Mutes the scrambled signal.

The mute period based on the determination output of the viewability determination circuit 25 is canceled when the key update timing signal P ₂ is received. On the other hand, when the mute control signal generation circuit 31 counts the first key update timing information P ₂ after the pulse P ₁ of the channel switching timing signal, it changes the signal 31a from logic “0” to logic “1” and two signals. When the eye key update timing information P ₃ is counted, it is returned to the logical “0”. Signal of logic "1" is scramble ON
Since the / OFF signal is "ON" and exhibits a logical "1", A
It passes through the ND circuit 30 and becomes the output 30a. As a result, the mute is ON / O even after the viewability determination output is "viewable".
The FF signal remains at the level indicating "ON". afterwards,
The mute is released by the second key update. The mute ON / OFF signal is represented by e = a.b + c + d. d is a mute pulse signal.

According to such an embodiment, when the key information K _B0 transmitted at the time of channel switching cannot be obtained (in the case), it can be used to mute even during the descrambling period. According to such a method, the optimum mute period can be set even when the update cycle is indefinite.

FIG. 3 is a block diagram showing another embodiment of the pay broadcast receiving apparatus according to the present invention. In the embodiment of FIG. 1, when the key information K _B0 , B ₀ can be received at the time of channel switching, the information for one cycle is wasted. The following examples address such drawbacks.

In the configuration of FIG. 3, the viewability judging circuit 25 collates and judges contract information when switching channels. As a structure for this purpose, the channel switching timing signal from the channel selection circuit 23 is used as the viewing permission / inhibition determination circuit 25.
To supply.

According to such a configuration, the optimum mute period depending on whether or not the contract information B0 can be received between the time when the viewability determination circuit 25 switches the channel and the time when the first update timing information P2 is received. Can be set.

FIG. 4 is a time chart showing the operation of the embodiment of FIG. 3, and (a) to (f) show the same signals as in FIG.
(G) is a viewability determination output in case of, (h) is a viewability determination output in case of, and (i) is mute ON in case of
/ OFF signal, (j) shows the mute ON / OFF signal in the case of, respectively.

From the time the channel is switched to the time when the first update timing information P2 is received, the viewability determination circuit 25 displays the contract information B0.
If you can receive (in the case of), as long as there is a contract such as fee payment, information is limited to the period when switching channels.
Since K _B0 can be obtained, correct descrambling can be performed in the next cycle. In this case, the viewability determination output is, as shown in (g), from the time the channel is switched until the first update timing information is received.
It becomes "viewing prohibited", the mute ON / OFF signal becomes as shown in (i), and the mute is applied during the synchronization.

Further, when the viewability determination circuit 25 cannot receive the contract information B0 from the time of switching the channel until the first update timing information P2 is received (in the case), the viewability determination circuit 25 determines that the contract information Since the collation cannot be performed, the determination output is set to "viewing prohibited" until the second key update timing information is received, as shown in (h). According to such a viewability determination output, as in the embodiment of FIG. 1, it is possible to mute during the second key update from the time of channel switching. Mute like this
The ON / OFF signal is as shown in (j).

If the key information is not obtained even when the update timing information P3 is received, the viewability determination output may be set to "viewable" and muting may be continued until the key information is obtained.

Further, in the embodiment of FIG. 1, the mute control signal generating circuit 31 may generate a mute pulse until the key update timing signal P ₃ is counted from the time when the channel switching timing signal is generated.

According to such an embodiment, since the shortest mute period is determined according to the reception situation of the contract information at the time of channel switching, the holding time for reception becomes short.

Further, in order to cope with the shortage of the mute period, a mute ON / OFF signal as shown in FIG. 6 (i) may be created. The mute ON / OFF signal is the update cycle T
In consideration of the above, even if the first update timing signal P2 is received, the mute period is further extended for a predetermined period and the period indicated by D is muted. Even in this case, the same effect as the first embodiment can be obtained. Further, as shown in the period B, even if the mute is continued until the second update timing signal P3 is received, the same effect as in the first embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, even when the contract information update period is indefinite, the optimum mute period can be set, and information can be received without waste. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the pay broadcast receiving apparatus according to the present invention, FIG. 2 is a time chart showing the operation of the pay broadcast receiving apparatus of FIG. 1, and FIG. 3 is a pay broadcasting according to the present invention. FIG. 4 is a block diagram showing another embodiment of the receiving device, FIG. 4 is a time chart showing the operation of the embodiment shown in FIG. 3, FIG. 5 is a block diagram showing a conventional pay broadcast receiving device, and FIG. It is a time chart which shows operation | movement of the pay broadcast receiving apparatus of the figure. 23 …… Channel selection circuit, 24 …… Switch, 25 …… Viewability judging circuit, 26 …… Key gate circuit, 27,30 …… AND circuit, 28 …… Descramble circuit, 31 …… Mute control signal generation circuit , 32 …… Mute circuit.

Claims (2)

(57) [Claims] 1. Transmission program information, scramble ON / OFF information indicating whether or not the transmission program information is scrambled, key information for descrambling the scrambled transmission program information, and the key information is updated. Means for receiving the key update timing information and the contract information for obtaining the key information, which is sent every predetermined period, and the descrambling of the scrambled transmission program information based on the key information. Scrambling means, mute means for selectively muting the output of the descrambling means, viewing availability determining means for matching the contract information to determine viewing availability, and the scrambling ON / OFF information indicates that the scrambling is “ON”. When the channel switching timing signal indicating that the channel has been switched is input when A pay broadcast receiving apparatus comprising: a mute control unit for stopping the mute operation of the mute unit according to the key update timing signal inputted to the eye. 2. Transmission program information, scramble ON / OFF information indicating whether or not the transmission program information is scrambled, key information for descrambling the scrambled transmission program information, and the key information is updated. Means for receiving the key update timing information and the contract information for obtaining the key information, which is sent every predetermined period, and the descrambling of the scrambled transmission program information based on the key information. Scrambling means, mute means for selectively muting the output of the descrambling means, and mute control for muting the mute means when a channel is switched when the scrambling ON / OFF information indicates scrambling "ON" Means and the contract information are collated to determine whether or not viewing is possible and the channel is switched. And a determination unit that determines whether or not the contract information that can be collated is received before the first key update timing signal is input, and the mute control unit can collate the determination unit. A pay broadcast receiving apparatus, characterized in that, when the contract information is received, the mute operation is stopped at a timing corresponding to the first key update timing signal.