JPS5885685A - Picture signal transmitting system - Google Patents

Abstract

PURPOSE:To prevent wire tapping and furtive glance by a general subscriber, by making a CATV system have a privacy function so that an independent tariff system can be taken, in a picture signal transmission system. CONSTITUTION:When a subscriber's terminal B applies picture service to a program center A by operating a keyboard 14, a key code train of a secret number set in advance is transmitted to the subscriber's terminal B through a bi-directional circuit F. It is stored in a key code memory 13 in the terminal B. In this case, in a program center A, a key code signal for switching a channel is superposed on a picture signal from a picture file group 1 and is multiplexed, in an in-channel signal superposing device 2, and is sent to the terminal B through a CATV circuit D. In the terminal B, code information from the memory 13 is collated with an in-channel signal, a channel selector 11 is switched, and picture service is obtained, therefore, a subscriber's terminal which receives no key code train cannot discriminate contents of a program.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image signal transmission system, and in particular to an image signal transmission method in which a terminal device of a cable television (community viewing) system is provided with a secret function and an independent charge system can be adopted. be.

In the image service system, terminal devices (general home telephones and TV receivers) are connected to the zologram center where service images are stored using individual wiring.
There is a so-called cable television (CATV), which combines a VR8 system with a secret call function, a terminal device, and a program center, and multiplexes several ten channels of image signals and transmits them over a single coaxial cable.

The former VHS system has the feature of having a secret communication function, but has the disadvantage that transmission lines must be installed individually and are expensive. On the other hand, although the cost of installing a transmission line in the CATV system is low, it has the disadvantage of not being able to maintain confidential communications. In this way, the VR8 system and CATV system have advantages and disadvantages.

Among these, the present invention relates to an image signal transmission system in which a CATV system is provided with a confidential communication function and an independent fee structure can be adopted.

A CATV system multiplexes image signals of several dozen channels, connects the terminal side and a program center via a single coaxial cable transmission line, and by operating a keymate on the terminal side, the terminal subscriber can receive broadcast television. You can see a wide variety of services (programs). However, for this convenience, specific programs have an independent fee structure,
It is difficult to add a secret function. In order to provide this currently existing system with a confidential communication function, a channel selector sealed by a channel selector subscription is operated on the terminal side or by a remote control from a program center, and an image is output.

However, according to this method, the subscriber can easily estimate the contents of the sealed channel selector section, and can enjoy 9 free viewings as before. Furthermore, the operation for sealing the channel selector section in this way is very troublesome, and there is also the disadvantage that the terminal side and the program center must be connected with a remote control cable.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image signal transmission system that eliminates the above-mentioned drawbacks of the prior art and prevents subscribers from easily watching programs by eavesdropping.

The present invention connects a program center and terminal devices to a CATV line, and also connects the center and terminal devices to a bidirectional line, or divides the frequency within the free band of the CATV line for each terminal device. , or the system is configured so that communication can be performed using time-sharing, and when a terminal subscriber requests a service program using a keymate using a communication line, the control device of the program center sends a key code string to the terminal subscriber, The terminal subscriber stores it in the keycode memory. Then, at the program center, a key code signal that triggers channel switching is superimposed on the video signal. Therefore, by switching the channel selector while checking the code information obtained from the key code memory and the in-channel signal, the terminal subscriber who has not received the key code string in advance can use one unified program. It is set so that it cannot be received.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a schematic system diagram of a CATV system, where A is a program center (service center) that accommodates various image file groups. B1 to B3 indicate a plurality of subscriber terminals, and the home 'l' V C1-C of each terminal is
m and the program center are connected by a common CATV line, and each subscriber's terminal operating device (f-tshuphone telephone or a dedicated terminal using a telephone line)
E, -E3 and the program center person are connected by two-way lines F1%F3.

FIG. 2 shows a part of the schematic configuration of FIG. 1.

In Figure 2, to simplify the explanation, program center A
A case will be explained in which one subscriber terminal B is connected to the network.

In FIG. 2, program center A includes various image file groups 1, an in-channel signal superimposing device 2 that superimposes the image data successively generated from the image file group 1, and an in-channel signal, and multiplexes the superimposed signals. a multiplexing device 3 for transmitting to subscriber terminals; an in-channel signal generating device 4; a control device 5 for controlling the in-channel signal generation and in-channel signal superimposition; and a key for generating a key code string. It consists of a code string generation circuit 6 and a line interface 7 connected between the subscriber bidirectional line and the control device 5.

Further, subscriber terminal B includes a branching device 8 that branches image data sent via the CATV line to other subscriber terminals, and a demodulator 9 that demodulates the multiplexed image data.
An in-channel signal separation device 10 that separates only the in-channel signal from the demodulated image data, a channel selector 11 that selects an arbitrary channel from several tens of image signal channels, and a controller 12 that controls them. ,
A key code memory 13 stores the key code string obtained from the program center A via the two-way line F, a key gate (for example, a button telephone) 14 that requests a desired program from the program center A, and a key date. 14, a changeover switch 15 for connecting the bidirectional line F between requesting a desired program and storing a key code string from the program center;
It has a television receiver 16 for general home use, and these are connected by wiring as shown in the figure.

As mentioned in FIG. 1, program center A and subscriber terminal B are connected by a CATV line for transmitting image signals and a bidirectional line F for communication between the two.
Now, when subscriber terminal B applies for a key data image service, program center A uses line interface 7,
When the service is received via the control device 5, at the same time, a key code string generation circuit 6 that generates a preset PIN number is sent to the subscriber terminal via the control device 59, line interface 7, and bidirectional line F. Send to B. Therefore, subscriber terminal B stores the received specific key code string in key code memory 13. At this time, in the program center A, the key code signal (in-channel signal) that is a trigger for channel switching is superimposed on the image signal of the image file group 1 through the in-channel signal superimposing device 2, as will be described later. do. The superimposed signals are multiplexed in the multiplexer 3 and sent to the subscriber terminal B via the CATV line.
sent to. Subscriber terminal is key code memo IJ 13
The channel selector 11 is switched while comparing the code information obtained from the in-channel signal with the in-channel signal. As a result, the television receiver 16 receives a series of programs, ie, image services.

Therefore, subscriber terminals that have not received the above-mentioned key code string in advance will not be able to receive one unified program. In other words, are the images on a particular channel from various products? -I
This is because it lacks J-character and does not mean that a certain program has been received.

In particular, by speeding up channel switching and making several channels dummy, it is possible to make the program contents indiscernible to subscriber terminals without a key code string. Note that dummying several channels here refers to making several channels into completely white or checkered images in advance, which will be explained later in FIG. It means confusing.

Here, the key code is a problem for a particular subscriber terminal, but the key code is different for each program and can be changed depending on the date and time, and can be developed into as many random code strings as necessary. This key code simply indicates the order of channel numbers, and channels are switched in synchronization with an in-channel signal included in a television signal.

Next, an example of a key code string is shown in FIGS. 3 and 4 and will be described. The key code string is transmitted to the subscriber terminal as shown in FIG. 3, where M indicates channel MO, Mn indicates channel Mn, Mm indicates channel Mm, and they are transmitted in this order. Also, to obtain this key code string, the fourth
It is received as shown in the waveform diagram in the figure. The signal indicated by a broken line in the figure indicates an in-channel code. The signal indicated as DM is a dummy signal, which is a pseudo signal within a range that does not affect control.

Now, in order to obtain the key code string shown in FIG. 3, the subscriber terminal first uses the first code of the key code string to
2, select channel M, unconditionally. Next, CAT
When nl is received from the in-channel code of the V line M6 channel, channel Mn is selected. Then channel Mn
When receiving in-channel code nm of channel Mm
Select. The images sent from the program center A are transmitted by switching channels in synchronization with the switching of subscriber terminals. That is, the initially received key code string includes the channel number to be selected for switching and the in-channel code specifying the switching timing.

According to the above-mentioned embodiment, it is equipped with a confidential viewing function in that it is impossible to easily watch and watch the program continuously, and it is possible to pay an appropriate amount to each household.

It becomes possible to pay by program.

In the above-mentioned embodiment, a CATV line and a bidirectional line (telephone line) are used between the program center and subscriber terminals, but CAT
It is also possible to use the vacant band of the V line by frequency division or time division for each subscriber, and in this case, the installation of bidirectional lines can be omitted.

As is clear from the above-described embodiments, according to the invention, a program center and a plurality of subscriber terminals are connected to CATV lines, and the program center and subscriber terminals are connected via bidirectional lines or In addition, an arbitrary in-channel code is superimposed on the blanking part of the video signal from the program center and output, and the subscriber terminal uses the code tl[ obtained from the key code memory].
The channel selector is switched while checking the in-channel signal, and subscriber terminals that have not received each key code in advance cannot receive a single program, so general subscribers can easily switch the channel selector. Since the program cannot be viewed by eavesdropping, appropriate billing for each household and billing for each log can be achieved.

[Brief explanation of the drawing]

The attached drawings are for explaining one embodiment of the present invention, and FIG. 1 is an overall configuration diagram of the CATV system, FIG. 2 is a detailed circuit configuration diagram thereof, and FIG. FIG. 4 is a diagram showing an example of the output waveform of each key code. A...Program center, B...Subscriber terminal, 01
~C3...TV reception @, D...CATV line%
E, ~E3... Terminal operating device, Ft%F3... Bidirectional line, 1... Image file group %2... Channel signal superimposition device, 3... Multiplexing device, 4... In-channel signal generation device, 5... Control device, 6... Key code string generation device, 7... Line interface, 8...
Branching device, 9... Demodulator, 1°... In-channel signal separation device, 11... Channel selector, 12...
Controller, 13... Key code memory, 14... Key chain, 15... Changeover switch, 16... TV receiver. Agent Patent Attorney Tadashi Akimoto District 1

Claims (1)

[Claims] A zologram center accommodating many types of image programs, and a plurality of subscriber terminal devices connected to the zologram center via cable television lines, receiving image program services in response to requests through key operations, and outputting the services to TV receivers. An image signal transmission method in a cable television system consisting of a cable television system in which an in-channel code is superimposed on the cable television line connecting the program center and a plurality of subscriber terminal devices, and both are connected via a bidirectional line, Alternatively, each terminal device is configured to be able to communicate within the vacant band of the cable television line by using frequency division and time division, and the program center is configured to:
comprising a key code string sending circuit that sends a key code string of a subscriber who requested the service to a subscriber terminal device when an image program service is requested via the communication line;
The subscriber terminal device has a key code storage circuit that stores a key code string sent from the program center, and uses the contents of the key code storage circuit and the in-channel code in the received image program signal to determine whether the cable television An image signal transmission system comprising a channel selector circuit capable of selecting a channel of a line so that only subscriber terminal devices that have previously received a specific key code string from a program center can view and listen.