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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a two-way cable television system. More
particularly, the invention relates to a chargeable-program-receiving
limit setting system in a two-way cable television system.
2. Background of the Invention
In general, in a cable television system (hereinafter referred to as "a
CATV system") there are non-chargeable (or free) programs and chargeable
programs. For chargeable program, the charging information for chargeable
programs received by each subscriber is stored in a register in the
terminal unit of the subscriber, and is then read out by polling at the
central facility in the CATV system.
A conventional two-way CATV system of this type is as shown in FIG. 5.
In FIG. 5 a central facility 1 transmits data and video signals from a
video source 6 and receives "up" data. A CPU (central processing unit) 7
performs data communication, audience control and charging process. An FSK
transmitter 8 transmits data to CATV lines. A modem 9 receives "up" data
through telephone lines from subscribers.
Further in FIG. 5, a CATV terminal unit 2 is provided to each subscriber.
An FSK receiver 10 demodulates data which are transmitted from the central
facility 1 (hereinafter referred to as "a center"). An A controller 11
performs the audience control of the terminal unit 2 according to the
operation made by the subscriber or according to "down" data or performs
data communication with an "up" communication module 3. The CATV terminal
unit 2 further includes a converter 12 and a descrambler 13 and is
connected to a television set 4. A telephone line exchange network 5 links
the central facility 1 to the CATV terminal unit 2.
The arrangement of the "up" communication module 3 is as shown in FIG. 6. A
telephone modem 14 applies "up" data to telephone lines which are to be
transmitted to the center 1 from the terminal unit 2 and a B controller 15
performs communications with the A controller 11, controlling an event
register 16 (described later), and transmitting "up" data. The event
register 16 is used to store a history of received chargeable programs
(hereinafter referred to as a "chargeable program reception history").
A charging system in the two-way CATV system thus organized will be
described.
The A controller reads a chargeable program identifying code (hereinafter
referred to as "an event code") contained in a video signal transmitted
through the descrambler 13, and communicates it to the B controller 15 in
the "up" communication module 3. The B controller 15 refers to the event
register 16 to detect whether or not that event code has been stored
therein. If not, the controller B causes the event register 16 to store
the event code as a new one. In this manner, whenever the subscriber
receives a chargeable program, the event code is stored in the event
register 16. The event registers 16 of all the terminal units 2 at the
subscribers are equal to one another in storage capacity. In each of the
event registers, the chargeable program reception data can be stored up to
the limit of the storage capacity.
When the event codes have been stored in the event register to its full
storage capacity chargeable programs cannot be received any longer.
The chargeable program reception data thus stored in the event register 16
is periodically transmitted to the center 1. That is, when a chargeable
program reception data collecting instruction is issued from the center by
polling, the contents of the event register 16 at that time are read out
by the B controller in the "up" communication module 3 and are modulated
by the telephone modem 14. The output of the telephone modem 14 is
transmitted as "up" data to the center 1 through the exchange network 5.
At the center 1, the "up" data is demodulated by the telephone modem 9,
and according to the output of the telephone modem 9, the charging process
is carried out by the CPU 7.
In the case where the "up" data communication is performed through
telephone lines, the time required for collecting "up" data from each
terminal unit is of the order of thirty seconds. As the CATV system
increases in scale, the time required for collecting "up" data from all of
the terminal units is increased, for instance, to several days. If, during
this period, the up communication module 3 is disassembled, and the event
register 16 is modified to erase the event codes, then the subscriber will
not be charged for the reception of the chargeable programs.
The monetary loss due to such dishonest reception of chargeable programs
may be reduced by decreasing the storage capacity of the event register.
However, the method is still disadvantageous in that the chance of earning
an income is lost as much as the storage capacity of the event register is
decreased.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to eliminate the
above-described difficulties accompanying a conventional two-way CATV
system.
The foregoing object and other objects of the invention have been achieved
by the provision of a chargeable program receiving system for a two-way
CATV system. According to the invention, a central facility is provided
with a subscriber file in which audience control data and credit limits
which determine chargeable program receiving limits for respective
subscribers are stored. A central processing unit transmits the credit
limits, in a command format, to the terminal units, and each of the
terminal units is provided with an event register for storing a history of
receiving chargeable programs. A memory in the terminal unit stores the
credit limit transmitted from the central facility. A controller changes a
logical range of use of the event register according to the credit limit
stored in the memory. As a result, chargeable program receiving limits are
provided respectively for subscribers.
The nature, principle and use of the invention will become more apparent
from the following detailed description when read in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 through 4 are diagrams for a description of a chargeable program
receiving limit setting system in a two-way CATV system according to this
invention;
More specifically, FIG. 1 is a block diagram showing the arrangement of a
central facility and the arrangement of a terminal unit in the CATV
system;
FIG. 2 is a block diagram showing an "up" communication module provided on
the side of the terminal unit;
FIG. 3 is an explanatory diagram showing the format polling command data
transmitted to the terminal unit; and
FIG. 4 is an explanatory diagram, partly as a block diagram, schematically
showing a subscriber file the contents of which are reflected on the
terminal units; and
FIG. 5 and 6 show a conventional two-way CATV system;
More specifically, FIG. 5 is a block diagram showing the arrangement of a
central facility and the arrangement of a terminal unit in the
conventional two-way CATV system; and
FIG. 6 is a block diagram showing the arrangement of an "up" communication
module provided on the side of the terminal unit.
DETAILED DESCRIPTION OF THE INVENTION
One preferred embodiment of this invention will be described with reference
to FIGS. 1 through 4. In FIGS. 1 through 4, parts corresponding
functionally to those already described with reference to FIGS. 5 and 6
are therefore designated by corresponding reference numerals, and the
preceding description is applicable thereto.
As shown in FIG. 1, at the center 1, a subscriber file 19 holding the
addresses of terminal units 2 at subscriber locations and subscriber
audience control data is connected to the CPU 7. The audience control
data, including the history of payment made by each subscriber and the
names of subscribers who have ever made a dishonest reception of
chargeable programs, is referred to so that the subscriber who has not
satisfactorily paid for the reception of chargeable programs or the
subscriber who has ever dishonestly received chargeable programs is
limited in reception of chargeable programs. Therefore, according to the
audience control data, a credit limit (CL) is provided for each of the
subscribers and stored in the subscriber file 19. The CPU 7 polls the
terminal units at the subscriber locations through the CATV line with the
data of the subscriber file 19 in a command format. The contents of the
subscriber file 19 can be added, changed and eliminated by an on-line
terminal unit 20 at the center 1 or by periodic batch processing. The
changed file contents are reflected on the terminal units 2 and the "up"
communication module 3 at the subscribers by the aforementioned polling.
FIG. 3 shows the command format of the polling and FIG. 4 schematically
shows the subscriber file which is reflected on the terminal units 2.
When, in each of the terminal units 2, a command having its own address is
received, the credit limit included in the command is stored in a memory
21 in the "up" communication module 3, and the logical range of use of the
event register 16 is determined by the B controller 15. The number of
chargeable programs which can be received before polling for charges is
increased with the logical range of use thus determined. The credit limit
may be increased for a reliable subscriber from whom a high income can be
obtained. For a subscriber who has ever dishonestly received chargeable
programs, the credit limit may be set to zero so as to inhibit his
receiving any chargeable programs.
FIG. 3 shows a command format in the polling. The command includes a start
flag, an address, control information, a credit limit and a stop flag. The
address indicates a code given to each of the terminal units. The control
information is digital data for controlling access to the program signals
transmitted from the center 1. Each of the terminals has its own control
information. The credit limit designates a number of an event register 16
contained in each of the terminals. In other words, the credit limit shows
a receivable limit of the events for the respective subscriber.
The above information is stored in the subscriber file 19 of the center 1
shown in FIG. 4. These information data can be changed or deleted by a key
board operation of the on-line terminal unit 20 of the center 1 in
consideration of a subscriber's requirement, an honesty of the subscriber,
and a policy of the center side and the like.
FIG. 4 shows the CPU 7, the on-line terminal unit 20, and a content of the
subscriber file 19 of the center 1, which are reflected on the terminal
units 2. FIG. 4 also shows a condition of the terminal units corresponding
to the content of the subscriber file. An operation of these components
will be described hereinbelow in detail.
The center 1 periodically outputs one time a day or a week, for example,
information stored in the subscriber file to the subscriber terminals by
polling. If the information includes, for instance, a start flag, address
x, control information Vx, credit limit "6" and a stop flag, no subscriber
terminal actuates except for that having its own address X. The subscriber
terminal having the address X compares the control information Vx
transmitted from the center 1 with that stored in the memory 21 of the
subscriber terminal. In the case where the compared informations are
coincident with each other, nothing is changed. If not, on the other hand,
the information in the memory 21 is replaced by the new information
transmitted from the center 1. Therefore, new audience control information
is stored, as a data, in the memory 21 of the subscriber terminal.
Similarly, information of the credit limit "6" transmitted from the center
1 is compared with that (CL=6) stored in the memory 21 of the subscriber
terminal. In case that the two credit limits are coincident with each
other, nothing is changed. If not, the credit limit stored in the memory
21 is replaced by the new credit limit transmitted from the center 1. In
the device of the invention, the event registers 16 contain therein six
registers, as shown in FIG. 4. Therefore, if a subscriber terminal
contains the credit limit "6" as shown in the top in FIG. 4, it can
receive all of six events determined by the event register 16 in the
subscriber terminal.
Similarly, information stored in the subscriber terminal having its own
address Y or Z can be changed by another polling operation. In FIG. 4, the
subscriber, the address of which is Y, has its credit limit "2".
Therefore, this terminal receives merely two events. The subscriber the
address of which is Z has its credit limit "0" in FIG. 4 and, accordingly,
it can receive no event.
As described above, the memory 21 of each of the subscriber terminals can
be changed by polling. The subscriber can receive the events from the
center 1 according to information newly stored in memory 21 during the
polling. Each of the subscriber terminals keeps track of the events and
other video information received thereby. Data representing the content of
the event register is transmitted to the modem 9 of the center 1 through
the communication module 3 and the telephone line exchanging network 5.
Based on the event register data received from each of the subscriber
terminals, the center 1 can carry out the charging process and, further,
measure an audience rating of the program.
If a subscriber is dissatisfied with the content of the memory 21 of his
terminal unit, that is, an amount of his credit limit, he can call the
center 1 through a telephone line to request an increase in his credit
limit. Then, the center 1 changes information data stored in the
subscriber's own subscriber file 19 in the center side by a keyboard
operation of the on-line terminal unit 20, if the center side agrees to
grant his request.
In the CATV system of the invention, similarly as in the conventional CATV
system, the subscribers are charged for reception of chargeable programs
according to the event registers.
In the above-described embodiment of the invention, the "up" communication
module 3 is separate from the terminal unit 2. However, the invention is
not limited thereto or thereby. That is, the terminal unit 2 may be so
designed as to have an "up" data communicating function.
As is apparent from the above description, the chargeable program receiving
limits can be set respectively for the subscribers, in the CATV system of
the invention. Therefore, reception of chargeable programs by dishonest
subscribers can be prevented and the total income can be increased by
sufficiently charging credible and honest subscribers for reception of
chargeable programs. Even if a dishonest subscriber made a dishonest
reception of chargeable programs again, the monetary loss can be minimized
because of the decreased credit limit. Thus, the CATV system of the
invention will promise a reasonable income to the system operator.
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