JPH0379183A - Subscription broadcast receiver - Google Patents

Abstract

PURPOSE:To eliminate waste in the reception of information by controlling the operation of a muting circuit with the OR output of pulses for muting outputted with first and second key update signals and a specific signal after inputting a channel switching timing signal. CONSTITUTION:Program information from transmission equipment is inputted to the muting circuit 32 via a de-scrambling circuit 28, and program contract information and contract information are decided at a view feasibility/ infeasibility deciding circuit 25 when key update timing information is inputted, and the AND of view feasibility/infeasibility deciding output and scramble on/off information is inputted to the circuit 28. And a mute control signal generation circuit 31 which counts two key update timing signals after inputting the channel switching signal outputs the pulse 31a for muting and inputs the AND output with the scramble on/off information to a control circuit 29, and forms a mute on/off signal with view permission deciding output and the channel switching timing signal, etc., thereby, the muting circuit 32 is controlled.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a pay broadcast receiving device that mutes the audio of pay program information scrambled and transmitted from a transmitting side by determining whether or not it can be viewed. .

(Prior Art) In subscription TV systems, pay program information is encrypted using a predetermined scrambling law in order to prevent non-subscribers from viewing pay programs. The contract subscriber receives terminal information (for example, contract program information, terminal address information, etc.) specifying the subscriber's terminal from the transmitting side.

Descrambling (plain culture) can be performed by obtaining the key information for descrambling using (payment information, etc.). Non-subscribers cannot receive the key information and therefore cannot descramble the scrambled information into normal information. Note that the key information is updated periodically to prevent the scrambling rule from being decoded by malicious intent.

By the way, when the pay program information is audio information or video and audio information, if the scramble applied to the audio information is not properly descrambled, there is a risk that a loud noise will be generated and destroy the speaker. For this reason, each terminal is equipped with a viewing permission determination circuit that determines whether viewing is possible based on the terminal memory that registers the above terminal information, and when the judgment signal from this circuit denies viewing, the audio signal is muted. It's like J.

FIG. 5 shows a conventional pay broadcast receiver equipped with the above mute circuit.

In FIG. 5, 1 is a transmitting device and 2 is a receiving device.

The transmitting device 1 corresponds to one broadcast station and supplies program information to the scrambling circuit 3. The scrambling circuit 3 scrambles the pay program information and sends the normal program information to the transmission line 4 as it is.

The transmitting device W1 is located on the same transmission path as that for the above program information.
is a scramble O indicating whether or not the program information being transmitted is scrambled by another transmission path 5 to 9.
Sends N/OFF information, key information for descrambling, key update timing information indicating whether tJ1 information has been updated, contract program information indicating a contract program, and contract information indicating whether fees have been paid or not. do.

The receiving device 12 includes a channel selection circuit 11 .that selects the transmitting device 1 . A switch 1 that switches and connects transmission lines 4 to 9 according to a channel selection signal from a channel selection circuit 11.
2. Viewability determination circuit 13. A descrambling circuit 14 that descrambles program information from the transmission path 4. AND circuit 15 and key gate circuit 16 which respectively supply scramble ON/OFF information and key information to the descrambling circuit 14 when viewing is possible; a mute circuit 17 and a mute circuit 17 which mute the signal from the descrambling circuit 14;
The mute control circuit 18 controls the mute control circuit 18.

The operation of the above configuration is as follows.

The transmitting device 1 periodically updates the key information, contract program information, and contract information, but transmits them before the time when they are actually used for descrambling. The viewing availability determination circuit 13 inputs contract program information, contract information (hereinafter these two pieces of information will be referred to as contract information), and key update timing information.
The contract information is checked against each other to determine whether viewing is possible.

The logical level (logic) in which the above judgment result indicates “viewable”
1'), it means that a contract has been made and the fee has been paid for the program, the AND circuit 15 is opened, the key gate circuit 16 extracts the key information, and the mute control circuit 18 is activated. A signal for turning off the mute circuit 17 is output. In this way, program information that has been normally descrambled can be viewed.

When the judgment result of the viewing permission judgment circuit 13 is at a logic level (logic "0") indicating "viewing station", there is no contract for the program, 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 that turns on the mute circuit 17. In this way, the signal resulting from abnormal descrambling is muted by the mute circuit 17. The above determination operation is performed every time key update timing information is received.

If the mute ON/OFF signal in the above case is 81, the scrambled ON/OFF signal is a, and the viewing permission determination result is b, then it can be expressed by the logical formula e=a-b.

b means "viewing stand".

In the case of normal program information that has not been descrambled, the output of the viewing permission determination circuit 13 becomes “viewable”, and a signal to turn off the scrambling is supplied to the descrambling circuit 14. 14 passes the information as is, and the mute circuit 17 also passes the signal.

In the above, the judgment operation of the viewing permission judgment circuit 13 is delayed, and there may be an inconvenience that muting is not applied even though correct key information is not obtained.

FIG. 6 is a time chart showing in detail the judgment operation when switching channels, (a) shows the program information for which the channel was switched, (b) shows the 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 permission determination, and (f) is for descrambling. (g) shows the viewing permission determination output, (h>, (i) shows mute ON
/OFF signals ■ and ■ are shown, respectively.

In FIG. 6, when switching from channel A to channel B, first, the channel switching timing signal (b)
presents a pulse P1. This pulse P1 is supplied to the mute circuit 17 via the mute control circuit 18, and causes the circuit 17 to perform a mute operation. This is due to momentary interruptions and discontinuities in the signal due to channel switching.
This is to eliminate noise, which occurs instantaneously regardless of whether it is OFF or not.

The transmitting device 1 transmitted the key information one cycle ago, and for example, the key information contains ^2. The program information in the cycle in which the contract information A2 is transmitted can be normally descrambled using the key information KAI transmitted in the previous cycle. in this case,
Whether or not the key information KAI is to be acquired for descrambling is determined by comparing the contract information A1 received at the same time.

Now, consider the case where the channel is switched.

At time t1, the information stored as the key information is A2, and since the received program information cannot be decoded with such key information, the information stored as the key information is A2, as shown in (g), until the update timing signal P2 appears. During period A, the viewing permission determination signal is set to "viewing stand". This will mute 0N10
．． FF signal becomes l' ON T+, mute circuit 1
7 is muted.

Next, when the update timing signal P2 is received, the previous cycle (
At the same time, the mute ON/OFF signal O is turned OFF'', and the mute circuit 17 passes the descrambled signal without muting it.

Expressing the mute ON/OFF signal in this case as a logical formula, e=a −
It becomes b+c.

If after tl, during the first update, Ke o
, Bo cannot be stored in the terminal information memory, the key information for channel A stored before channel switching is
3 is retained and descrambling is performed. In such a case, normal descrambling is not performed, so muting is also required during the period until the next update timing signal P3.

To deal with this lack of mute period, conventionally,
A mute ON/OFF signal (■) as shown in (+) was created. Mute ON/○FF signal■ is
Considering the update period T, the first update timing signal P2
Even if the message is received, the mute period is further extended for a predetermined period, and the mute is applied for the period indicated by D. However, when setting the mute period in this manner, the optimum period cannot be determined when the update cycle is indefinite.

Alternatively, as shown in period B, there is also a method of continuing muting until the second update timing signal P3 is received. However, in such a method, if key information Keo and Bo can be received at the time of channel switching, program information for one cycle cannot be obtained. The former method of using the D period also has this drawback, and the waiting time for reception becomes long.

(Problems to be Solved by the Invention) Conventional pay broadcast receiving devices set the mute period to
Because it is set to period B or period D (see Figure 6), if the correct key information is received when switching channels, one cycle's worth of information cannot be viewed, wasting the information and reducing reception waiting time. There were inconveniences such as an increase in

An object of the present invention is to eliminate the above-mentioned problems and provide a pay broadcast receiving device that can receive information without wasting information even when correct key information is not obtained or obtained when switching channels.

[Structure of the Invention] (Means for Solving the LFT Problem) The first invention provides transmission program information, scramble ON/OFF information indicating whether or not the program information is scrambled, key information for descrambling, means for receiving contract information for obtaining key update timing information and key information; a descrambling circuit; a mute circuit for selectively muting the output of the descrambling circuit; and determining whether or not viewing is possible based on the contract information. Further, a mute control signal generation circuit is provided which outputs a mute pulse according to the first key update timing signal and the second key update timing signal after inputting the channel switching timing signal without indicating the time of channel switching. , when the scramble ON/OFF information indicates scramble "ON", the mute circuit is controlled by the logical sum output of the output of the viewing permission determination circuit, the channel switching timing signal, and the mute pulse signal. It is characterized by

A second invention relates to the viewing permission determination circuit in the first invention, which determines whether viewing is possible based on the contract information and also determines whether the contract information of program information received after channel switching can be verified. The present invention is characterized in that, if possible, at the timing of the next key update timing signal, a determination is made to change the viewing permission determination output, which was set to “viewing prohibited” at the time of channel switching, to “viewing permitted”.

(Function) According to this configuration, in the first invention, key information is obtained by the mute pulse output from the mute control signal generation circuit after the mute period determined by the output of the viewing permission determination circuit. Mute is applied until the second key update, and the mute period does not exceed. Also,
In the second invention, since the output of the viewing permission determination circuit is set to "viewing prohibited" until the update period in which key information is obtained, it depends on whether or not key information is obtained during the period after channel switching. The shortest mute period can be determined.

(Example) Hereinafter, the present invention will be explained in detail with reference to illustrated examples.

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

In FIG. 1, 24 is a set of information (program information, scramble ON/OFF information, Wl information, key update timing information) from a plurality of transmitting devices (paths shown).

23 is a channel selection circuit that controls the switch 24.

The program information is sent to the descrambling circuit 2 via the switch 24.
8, and the descrambled output is input to a mute circuit 32.

The two pieces of contract information (program contract information, contract information) and key update timing information are each input to the viewing permission determination circuit 25, and the two pieces of contract information are compared and determined at the timing of the key update timing information. ing. If the contract information is compared with each other, the viewing permission determination circuit 25 derives a determination output indicating "viewing is permitted", and if not, it derives a determination output indicating "viewing is prohibited".

The key information is supplied to the key gate circuit 26 and scrambled
The N/OFF information is supplied to the AND circuit 27. The key gate circuit 26 is gate-controlled by the viewing permission determination output, and extracts the correct key information when the output is ``viewable''.The AND circuit 27 is gate-controlled by the viewing permission determination output, and scrambles ON/OFF. OFF information is ON
(Scramble), the descrambling circuit 28 is enabled.

The mute control signal generation circuit 31 is a circuit provided according to this embodiment, and contains key update timing information and a channel switching timing signal from the channel selection circuit 23. Mute control signal generation circuit 3
1 outputs a mute pulse while counting two key update timing signals after inputting a channel switching timing signal. The output 31a of the mute control signal generation circuit 31 is
The AND circuit 30 generates an AND output 30a with the scramble ON/OFF information, which is input to the mute control circuit 29.

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

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

In FIG. 2, signals (a) to (f) are the same as in FIG. 6. Signal (Q) indicates the viewing permission determination output, (h) indicates the signal 31a, and (+) indicates the mute ON/OFF signal.

Now, when the channel is switched at time t1, first, the channel selection circuit 23 supplies the pulse P1 of the channel switching timing signal (b) to the mute control circuit 29 and the mute control signal generation circuit 31. The pulse P1 is
By being input to the mute control circuit 29, the mute circuit 32 is activated regardless of the scramble ON/OFF signal.
This is the signal that mutes the channel and eliminates the noise that occurs when switching channels.

Next, the viewing permission determining circuit 25 derives a determination output indicating "viewing not permitted" while the first update timing signal P2 is received from time t1. This judgment output is logically ANDed with the scramble ON/OFF signal a-b in the mute control circuit 29, and the mute circuit 32 mutes the scramble signal using the resulting mute ON/OFF signal.

The mute period based on the determination output of the viewing permission determination circuit 25 is canceled when the key update timing signal P2 is received. On the other hand, when the mute control signal generation circuit 31 counts the first key update timing information P2 after the pulse P1 of the channel switching timing signal, the mute control signal generation circuit 31 converts the signal 31a to a logic "OP".
+ is changed to logic "1", and when the second key update timing information P3 is counted, it is returned to logic "O". Logic 111 PI
For the signal, the scramble ON/OFF signal is “ON”
, and since it exhibits logic ``1'', ANC) circuit 3
0 and becomes the output 30a. As a result, even after the viewing permission determination output becomes ``viewable'', mute ON/
The OFF signal remains at the level indicating "ON".

After that, muting is canceled by the second key update. The above mute ON/OFF signal is e-a-b+c+
It is represented by d. d is a mute pulse signal.

According to such an embodiment, when the key information KBO transmitted at the time of channel switching cannot be obtained (in the case of ■), muting can also be applied during the period in which descrambling is performed using this information. According to such a method, an optimal mute period can be determined 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 shown in FIG. 1, if key information Keo and Bo can be received at the time of channel switching, information for one period is wasted. The following embodiments address these shortcomings.

The configuration shown in FIG. 3 is such that the viewing availability determining circuit 25 verifies and determines contract information when switching channels. As a configuration for this purpose, a channel switching timing signal from the channel selection circuit 23 is supplied to the viewing availability determination circuit 25.

According to such a configuration, the contract information B in the first key information period Kso at the time of channel switching.

The optimal mute period can be set for ■ when the message can be received and ■ when the message cannot be received.

FIG. 4 is a time chart showing the operation of the embodiment shown in FIG. 3, and (a) to (f) show the same signals as in FIG. 2. (g
) is the viewability determination output in case of ■, (h) is the viewability determination output in case of ■, (i) is mute ON/in case of ■
OFF signal, (j) is mute ON/OFF in case of ■
The signals are shown respectively.

If contract information Bo can be received at the time of channel switching ■, as long as the contract such as fee payment is in place, the key information KBO can be obtained during the channel switching period.
Correct descrambling can be performed in the next cycle.

In this case, as shown in (q), the viewing permission determination output becomes a "viewing stand" from the time of channel switching until the first update timing information is received, and the mute is turned on.
The /OFF signal becomes as shown in <i), and muting is applied for the same period.

If the contract information Bo cannot be received at the time of channel switching, the viewing permission determination circuit 25 cannot check the contract information, so the determination output is the second key update timing information as shown in (h). “Viewing stand” until reception is received
Make it. According to such a viewing permission determination output, similarly to the embodiment shown in FIG. 1, muting can be applied from the time of channel switching until the second key update is performed. Such a mute ON/OFF signal is as shown in (j).

Incidentally, if the key information is not obtained even after receiving the signal P3, it is possible to continue muting by setting the viewing permission determination output to ``viewing prohibited'' until the key information is obtained.

In the embodiment shown in FIG. 1, the mute control signal generation circuit 31 may generate the mute pulse from the time the channel switching timing signal is generated until the key update timing signal P3 is counted.

According to this embodiment, the shortest mute period is determined according to the reception status of contract information at the time of channel switching, so the time available for reception is reduced.

[Effects of the Invention] As explained above, according to the present invention, even when the update cycle of contract information is undefined, the optimum mute period can be determined, and information can be received without waste. be.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a pay broadcast receiver according to the present invention, FIG. 2 is a time chart showing the operation of the pay broadcast receiver of FIG. 1, and FIG. 3 is a pay broadcast receiver according to the present invention. FIG. 4 is a block diagram showing the operation of the embodiment of FIG. 3; FIG. 5 is a block diagram showing a conventional pay broadcast receiving device; FIG. 3 is a time chart showing the operation of the pay broadcast receiving device shown in the figure. 23... Channel selection circuit, 24... Switch,
25... Viewability determination circuit, 26... Key gate circuit, 27, 30... AND circuit, 28... Descrambling circuit, 31... Mute control signal generation circuit, 32
...Mute circuit.

Claims (2)

[Claims] (1) means for receiving transmission program information, scramble ON/OFF information indicating whether or not the program information is scrambled, key information for descrambling, key update timing information, and contract information for obtaining the key information; , a descrambling circuit that descrambles the scrambled program information based on the key information; a mute circuit that selectively mutes the output of the descrambling circuit; and a mute circuit that selectively mutes the output of the descrambling circuit, and determines whether viewing is possible by comparing the contract information with the above. A circuit for determining viewing availability; a mute control signal generation circuit for outputting a mute pulse according to the first and second key update timing signals after inputting a channel switching timing signal indicating when to switch channels; and scramble ON/OFF information. However, the scramble “ON”
and a mute control circuit that controls the mute operation of the mute circuit based on the logical sum output of the output of the viewing permission determination circuit, the channel switching timing signal, and the mute pulse signal. Paid broadcast receiving device. (2) means for receiving transmission program information, scramble ON/FF information, key information, key update timing information, and contract information; and a descrambling circuit that descrambles the scrambled program information based on the key information; a mute circuit that selectively mutes the output of the descrambling circuit; and a mute circuit that determines whether or not viewing is possible based on the contract information, and also determines whether or not the contract information of the program information received after channel switching can be verified; In such a case, the viewing permission determination circuit changes the viewing permission judgment output that was set to “viewing prohibited” at the time of channel switching to “viewing possible” at the timing of the next key update, and the scramble ON/OFF information is set to scramble “ON”.
a mute control circuit that controls the mute operation of the mute circuit based on the logical sum output of the output for determining whether viewing is possible, the channel switching timing signal, and the mute pulse signal. Receiving device.