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BACKGROUND OF THE INVENTION
The present invention relates to a CATV (cable television or community
antenna television) system.
In CATV systems, a center facility provides own programs and commercial
broadcast programs on the air to a plurality of subscriber terminal
apparatuses via transmission cables. In recent years, services of CATV
systems include data transmission. Further, bi-directional CATV systems
are now operated in which each terminal apparatus can transmit a signal
(i.e., an up signal) to a center facility. CATV systems limitedly operated
in schools, hotels, etc. are specifically called "CCTV (closed circuit
television) system."
In the conventional CATV systems, to select a desired program to see it on
a TV receiver, a user needs to refer to a program table that is
distributed in advance, find a channel of the desired program, and operate
a channel selection switch of a controller to set his terminal apparatus
to that channel. To make the TV receiver display a certain message
transmitted from the center facility, all the message data are stored in a
buffer memory of the terminal apparatus. The message data read from the
buffer memory are provided to a character generator, and an output of the
character generator is superimposed on a video signal.
In the above CATV systems, the center facility is required to prepare a
program table and distribute its copies in advance, and to broadcast
programs in accordance with the program table thus prepared. However, the
preparation of program tables needs some cost, and the flexibility of
program organization is reduced, for instance, the programs cannot be
altered once the program table is prepared. On the other hand, on the
terminal apparatus side, a user cannot know without referring to the
program table whether a desired program is scheduled to be broadcast. In
addition, a procedure of program selection is complex.
Further, in the above conventional CATV systems, because the number of
broadcast channels is insufficient, it is a general procedure that the
same chargeable program is rebroadcast in unfixed time periods rather
than, for instance, every 30 minutes. Therefore, when a viewer previously
stopped watching a certain program in the midst of its broadcast and wants
to see in another time the remaining a part of the same program that he
failed to see, he needs to wait for the next rebroadcast or to record that
program by a VCR etc. by checking in advance the start time of the next
rebroadcast. However, a cumbersome procedure is required to see the
rebroadcast program, or such an attempt sometimes results in a failure.
Further, the above conventional CATV systems employ a charging system in
which a viewer is charged for chargeable programs on a program-by-program
basis, as this system is called PPV (pay per view). In this system, a
viewer is charged a full charge even if he has ordered a program in the
midst of its broadcast. Since viewing of a certain program can be ordered
any time during its broadcast, a viewer is charged a full charge even if
he has ordered it only a short time before the end of the program.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a CATV system in which the
program organization can be performed with a high degree of flexibility,
such that a user can easily select a desired program, and the system
construction can be simplified.
Another object of the invention is to provide a CATV system in which where
a user who previously stopped watching a certain program, can easily view
the rest of the program during its rebroadcast.
Another object of the invention is to provide a CATV system which can
prevent the ordering of a program when only a short time remains before
the end of a program.
According to a first aspect of the invention, a CATV system comprises:
a center facility for transmitting, together with television signals of a
plurality of programs, display control data indicating program names of
the respective programs and channel data indicating channels numbers on
which the respective programs are being broadcast or to be broadcast; and
a plurality of terminal apparatuses, each comprising:
means for detecting the program names and the corresponding channel numbers
from the display control data and the channel data;
display means for displaying the detected program names on a TV receiver;
means for receiving an instruction indicating selection of one of the
program names being displayed on the TV receiver; and
means for tuning, based on the detected channel numbers, the terminal
apparatus to a channel on which the selected program is being broadcast or
to be broadcast.
According to a second embodiment of the invention, a CATV system comprises:
a center facility for transmitting a plurality of television signals of the
same program on different linked channels at different periods, and for
transmitting first data together with each of the television signals, the
first data including link data indicating at least one of the linked
channels having a predetermined linking relationship with an associated
channel, and start time data indicating a start time of the program on the
associated channel; and
a plurality of terminal apparatuses, each comprising:
means for calculating, when viewing of the program on a first channel is
stopped, a viewing period from the start time that is obtained from the
start time data to a viewing suspension time;
means for calculating, when an attempt to restart the viewing of the
program is made, elapsed times from the start times of the program on the
respective linked channels that are selected based on the link data to a
time of the restarting attempt, the start times being obtained from the
start time data; and
means for tuning the terminal apparatus to one of the linked channels based
on differences between the viewing period and the calculated elapsed
times.
According to a third aspect of the invention, a CATV system comprises:
a center facility for transmitting, together with a television signal of a
program, first data indicating an order permissible period during which
the program can be ordered and second data indicating a start time of the
program; and
a plurality of terminal apparatuses, each comprising:
means for calculating an elapsed time from the start time of the program
that is obtained from the second data to a present time; and
means for allowing an order of the program only when the elapsed time is
within the order permissible period that is obtained from the first data.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing a configuration of a CATV system
according to the present invention;
FIG. 2 is a block diagram showing a configuration of a center facility of
FIG. 1;
FIG. 3 is a block diagram showing a configuration of a terminal apparatus
of FIG. 1;
FIG. 4 shows an appearance of a remote controller;
FIG. 5 is a flowchart showing an operation of a terminal apparatus in a
first embodiment of the invention;
FIGS. 6(a) and 6(b) shows examples of data tables;
FIG. 7 shows pictures appearing on the screen of a TV receiver;
FIG. 8 is a flowchart showing an operation of a terminal apparatus in a
second embodiment;
FIG. 9 shows pictures appearing on the screen of the TV receiver;
FIG. 10(a) shows a structure of display data;
FIG. 10(b) shows addresses for the display data;
FIG. 11 shows a structure of in-band data;
FIG. 12 is a first part of a flowchart showing an operation of a terminal
apparatus in a third embodiment;
FIG. 13 shows a structure of in-band data;
FIG. 14 is a second part of the flowchart showing the operation of the
terminal apparatus in the third embodiment;
FIG. 15 shows an example of a picture appearing on the TV receiver;
FIG. 16 is a flowchart showing an operation of a terminal apparatus in a
fourth embodiment;
FIG. 17 shows a structure of in-band data; and
FIGS. 18(a) and 18(b) show examples of pictures appearing on the TV
receiver.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention are described hereinafter with
reference to the accompanying drawings.
FIG. 1 shows a configuration of a CATV system according to the invention. A
CATV system 100 includes a center facility (head end) 101, a plurality of
terminal apparatuses 102 and TV receivers 3 connected to the respective
terminal apparatuses 102. The center facility 101 receives by an antenna 1
commercial programs transmitted from a satellite 103, and also receives
ground-wave commercial programs by an antenna 2. Further, the center
facility 101 produces its own programs and messages (described later).
After subjected to a scrambling operation for prohibiting unauthorized
viewing (in the case of the own programs), a television signal is
distributed to the respective terminal apparatuses 102 via transmission
paths consisting of a main transmission cable 108, a main line amplifier
104, a main line branching amplifier 105, branch transmission cables 109,
branching devices 106 and maintenance devices 107. In general, the
distribution service is performed based on contracts with users (viewers),
who are charged accordingly.
The transmitted television signal is received by the terminal apparatus
102, subjected to a descrambling operation etc., and finally sent to the
TV receiver 3 for viewing by the user.
FIG. 2 shows a configuration of the center facility 101. The center
facility 101 includes the satellite-wave antenna 1, a BS converter 4 for
frequency-converting a signal received by the antenna 1, a signal
processor 5 and a mixer 6. A signal received by the ground-wave antenna 2
is also provided to the mixer 6 via a signal processor 7. A video signal
from a TV camera 8 or a program VCR 11, (i.e., a signal of a chargeable
program prepared in the center facility 101) is scrambled by a scrambler 9
to prohibit unauthorized viewing, modulated by a modulator 10, and finally
provided to the mixer 6. A control computer 15 produces in-band data and
data for FSK modulation that are to be transmitted to the terminal
apparatus 102. The output data of the control computer 15 is subjected to
a modulation to become the in-band data or to an FSK modulation in the
communication controller 16, and then sent to the mixer 6.
FIG. 3 is a block diagram showing a configuration of the terminal apparatus
102. In the case of ordinary broadcast programs, an RF signal sent from
the center facility 101 is input to a converter 20. The converter 20
selects a desired signal of a particular channel among input signals, and
frequency-converts the selected signal to produce an intermediate
frequency signal IF, which is provided to a descrambler 22 via a selector
21.
The descrambler 22 extracts scrambling data from the intermediate frequency
signal IF by amplitude detection, and performs a descrambling operation in
accordance with the extracted data. The descrambled signal is input to a
modulator 23 via an on-screen control IC (OSDIC) 31, which
frequency-modulates the audio signal part and amplitude-modulates the
video signal part and provides a resultant RF signal to the TV receiver 3.
In this operation, the on-screen control IC 31 superimposes a message and
other information on the video signal of a selected channel. In the case
of receiving a free broadcast of a free program and an all-around
emergency broadcast of, e.g., an earthquake or storm warning, the
intermediate frequency signal IF is directly provided from the selector 21
to the modulator 23, i.e., without passing through the descrambler 22.
A CPU 25 controls the entire terminal apparatus 102, i.e., a memory 26,
announcement displaying LED 27, buzzer 28, on-screen control IC 31, etc.
Under the control of the CPU 25, the memory 26 stores various character
data and setting data for the terminal apparatus 102 and various data
transmitted from the center facility 101, and the announcement displaying
LED 27 is flashed or the buzzer 28 is activated to inform the user of the
existence of a message transmitted from the center facility 101 or
occurrence of some abnormal event. The on-screen control IC 31 performs
various on-screen control operations such as signal superimposing.
A keyboard 29 has a key panel (not shown) used for the input of various
data. A remote control signal receiving section 30 receives and processes
an input control signal from a remote controller 35, and provides a
resultant signal to the CPU 25.
Referring to FIG. 4, a configuration of a remote controller 35 is described
below.
The remote controller 35 is constructed so as to transmit various data to a
remote control signal receiving section 30 in the form of infrared light.
The following buttons are provided on an operation panel of the remote
controller 35: a power button K.sub.1 for turning on/off the power; menu
button K.sub.2 for displaying a menu picture; order button K.sub.3 for
requesting viewing of a chargeable program; channel/response changeover
button K.sub.4 ; display button K.sub.5 for displaying various information
on the TV receiver 3; enter button K.sub.6 for confirming allowance of
inputting various data; clear button K.sub.7 ; memory recall button
K.sub.8 for reading out memory contents; mute button K.sub.9 for muting an
output audio signal of the TV receiver 3; volume-up button K.sub.10 ;
volume-down button K.sub.11 ; last channel recall button K.sub.12 for
displaying on the TV receiver 3 a program of a channel selected
immediately before the present channel; seesaw-like channel up/down button
K.sub.13 ; and numeral button group K.sub.NUM having ten buttons of a "1"
button through a "0" button. In the case of setting a timer operation, the
"1" through "7" buttons are used as days-of-the-week buttons (i.e., a
Sunday button through a Saturday button), the "0" button is used as an
every day button for designating all of Sunday through Saturday, and the
channel up/down button K.sub.13 is used as a morning/afternoon button. It
is noted that keys equivalent to the above buttons are also provided on
the key panel of the keyboard 29.
Next, an operation of the terminal apparatus 102 in a first embodiment is
described with reference to FIGS. 5-7.
Referring to a flowchart of FIG. 5, the CPU 25 first judges whether the
menu button K.sub.2 of the keyboard 29 or remote controller 35 has been
depressed (step S1). If the judgment is negative, the process goes to step
S6 (described later). If the judgment is affirmative, tuning is made to a
menu channel (step S2), a number of which is transmitted from the center
facility 101 and stored in a RAM (not shown) of the memory 26 in advance,
is selected. Character data of broadcast programs and channel data of the
respective broadcast programs are superimposed, as in-band data, on a
television signal on the menu channel.
For example, the CPU 25 detects, from the in-band data on the menu channel,
titles of movies, channel numbers and selection numbers (step S3). Then,
the CPU 25 produces a data table for correlating the channel numbers with
the selection numbers (step S4). More specifically, data tables as shown
in FIGS. 6(a) and 6(b) are produced.
Then, the CPU 25 sends data of the movie titles to the on-screen control IC
31 to have a menu screen as shown in part (a) of FIG. 7 displayed on the
TV receiver 3 (step S5), and is rendered in a waiting state.
When a viewer has input a number of a desired program using a numeral
button, it is judged, after execution of steps S1 and S6, whether a menu
picture is being displayed (step S7). If the judgment is negative, a
process corresponding to the depressed number is executed (step S18). If
the judgment is affirmative, tuning is made to the intended channel on the
basis of the data table of FIG. 6(a) or 6(b) (step S8). For example, using
the data table of FIG. 6(a), tuning is made to channel "91" when numeral
button "3" has been depressed.
After the channel selection, the CPU 25 detects a title, a broadcast start
time and a price of a movie from the in-band data on the selected channel
(step S9). Then, it is judged whether the program (i.e., movie) of the
selected title has already been bought (step S11). If the judgment is
affirmative, data for erasing is sent to the on-screen control IC 31, and
TV receiver 3 displays a picture corresponding only to the video signal
(step S17).
If the judgment is negative, the data of the channel number, present time,
movie title, broadcast start time, price, elapsed time from the start
time, etc. are sent to the on-screen control IC 31, and those data are
superimposed on a picture of the TV receiver 3 (step S12). Where channel
91 has been selected as in the above case, a picture as shown in FIG. 7(b)
is displayed. Then, the CPU 25 is rendered in a state of waiting for a
depression of the order button K.sub.3 (step S13).
After execution of steps S1 and S6, the CPU 25 judges whether the order
button K.sub.3 has been depressed (step S14). If the judgment is negative,
i.e., if a button other than the order button K.sub.3 has been depressed,
a process corresponding to the depressed button is executed (step S18). If
the judgment is affirmative, it is judged whether the CPU 25 is in the
state of waiting for a depression of the order button K.sub.3 (step S15).
If the judgment in step S15 is affirmative, the CPU 25 stores the movie
title, broadcast start time and price in a RAM (step S16), and sends data
for erasing to the on-screen control IC 31 to have a picture corresponding
only to the video signal displayed on the TV receiver 3 (step S17). As a
result, as shown in FIG. 7(c), only an image of channel 91 is displayed on
the TV receiver 3. Thereafter, the selected program becomes viewable upon
reaching its start time.
As described above, according to the first embodiment, since a desired
program can be selected by a simple input operation in accordance with
instructions appearing in a displayed picture, the procedure for program
selection on the terminal apparatus side can be simplified. Further, since
it is not necessary to distribute in advance pamphlets on which programs
are printed, a cost for preparing such pamphlets can be saved and the
program organization can be made flexible.
In a second embodiment of the invention, in addition to the operation of
the first embodiment, fixed messages for the menu picture are stored in
advance in a ROM of the terminal apparatus 102, and only variable messages
and display control data are transmitted from the center facility 101. In
the following description, it is assumed that 10-line messages are
displayed on the TV receiver 3 of the terminal apparatus 102 and messages
to appear on the first and tenth lines are fixed ones.
The operation of the second embodiment is described with reference to FIGS.
8-11.
First, the CPU 25 judges whether the menu button K.sub.2 has been depressed
(step S20). If the judgment is negative, the process goes to step S28
(described later). If the judgment is affirmative, the CPU 25 reads out a
menu channel number, which has been transmitted from the center facility
101 and stored in the RAM (not shown) of the memory 26 in advance, and
tuning is made to the selected channel (step S21).
Then, page data is set at page one (step S22). The page data is to specify
one of a plurality of pictures that can be displayed on the TV receiver 3.
Since display data of the first line on the first page has fixed contents,
i.e., it is a fixed message, the CPU 25 reads the display data from a ROM
(not shown) of the memory 26, instructs the on-screen control IC 31 of a
head address of the first line, and transfers the display data (step S23).
With this operation, a fixed message is displayed on the TV receiver 3
based on the display data. For example, in the case of a display picture
as shown in part (a) of FIG. 9, "PAY PER VIEW MENU" is displayed on the
first line.
Then, the CPU 25 detects display data of the second line on the page
specified by the page data (in this case, page one) from the in-band data
(described later), instructs the on-screen control IC 31 of a head address
of the second line, and transfers the display data (step S24). More
specifically, as shown in FIG. 10(a), the CPU 25 specifies the head
address by address data of 1 byte, and transfers the display data in the
form of a sequence of 1-byte character codes. As shown in FIG. 10(b), the
head address of the first line is "0."
In this case, the in-band data ID as shown in FIG. 11 is transmitted from
the center facility 101. In the in-band data ID, display position data DPD
of 1 byte includes page number data PD indicating a page to be displayed
and line number data LD indicating a line number of a line on the page
indicated by the page number data PD on which line the display data is to
be displayed. A display code DC of 24 bytes (corresponding to 24
characters) indicates the display data that should be displayed at the
position specified by the display position data DPD. Data for plural lines
are sequentially transmitted. For example, where the page number data PD
is "1" and the line number data LD is "3," a character sequence indicated
by the display code DC (consisting of a plurality of character codes) is
displayed on the third line of the first page.
Display processes for the third to ninth lines are similar to the process
for the second line (step S25).
The CPU 25 reads display data of the tenth line from the ROM (not shown) of
the memory 26, instructs the on-screen control IC 31 of a head address of
the tenth line, and transfers the display data (step S26). For example, as
shown in part (a) of FIG. 9, "TO EXIT PRESS MENU" is displayed on the
tenth line.
Then, the CPU 25 produces a data table for correlating selection numbers
with channel numbers (step S27). More specifically, the tables as shown in
FIGS. 6(a) and 6(b) are produced.
If it is judged in step S20 that the menu button K.sub.2 has not been
depressed, it is then judged whether a numeral button has been depressed
(step S28). When a button other than the numeral buttons has been
depressed, a process corresponding to the depressed button is executed
(step S37).
When a numeral button has been depressed, it is judged whether a menu
picture is being displayed (step S29). If the judgment is negative, a
process corresponding to the depressed numeral button is executed (step
S38). If the judgment is affirmative, the CPU 25 recognizes a channel
number corresponding to the depressed numeral button by referring to the
data tables of FIG. 6(a) and 6(b) (step S30). For example, if the numeral
button "1" is depressed, which means that the selection number is "1,"
channel number "89" is recognized.
Then, referring to the data table, it is judged whether a next page code
(next code) is stored in an area for storing a channel number
corresponding to the above selection number (step S31). If the judgment is
affirmative, the page data is increased (step S32), and the process goes
to step S23. More specifically, if, for example, the data table is the one
as shown in FIG. 6(a), and if number "9" has been selected, in which case
the next page code "FE" is stored instead of a channel number, one is
added to the page data to display the data of the next page.
If the judgment in step S31 is negative, it is judged whether the depressed
numeral button corresponds to a previous page code (previous code) (step
S33). If the judgment is affirmative, the page data is decreased (step
S34), and the process goes to step S23. More specifically, if the data
table is the one as shown in FIG. 6(b), and if number "8" has been
selected, in which case the previous page code "FD" is stored instead of a
channel number, one is subtracted from the page data to display the data
of the previous page.
If the judgment in step S33 is negative, it is judged whether a channel
number is stored (step S35). If the judgment is negative, the CPU 25 is
rendered in a state of waiting for an input. If the judgment is
affirmative, the terminal apparatus 102 is tuned to a channel of the
selected channel number (step S36), and the process is finished.
As described above, according to the second embodiment, since the fixed
messages are stored in advance in a memory, such as a ROM, of the terminal
apparatus 102, the amount of the display control data to be transmitted
from the center facility 101 can be reduced, i.e., the communication
efficiency can be improved. Further, the capacity of buffer memories for
receiving of the terminal apparatus 102 can be reduced, which means
simplification of the system.
Although in the second embodiment a fixed message is set on a line basis,
parts of a certain line may be selected as fixed message parts and a
variable message such as a time may be inserted into a fixed message. In
this case, the 1-byte address data of FIG. 10(a) specifies the head
address corresponding to the head position of the character codes to be
inserted. For example, in the case of displaying five characters starting
from the tenth character position of the fourth line, the tenth character
position is specified by the head address.
In the following, a third embodiment of the invention is described with
reference to FIGS. 12-15. It is assumed that a user started to watch a
movie titled "AAA" on channel 11 at 10:30 and stopped watching it at 11:35
to meet a visitor, and he attempts to view the rest of the same movie from
12:00.
Operation at the time of viewing suspension
Referring to FIG. 12, the CPU 25 first recognizes viewing suspension, i.e.,
power off of the TV receiver 3 by detecting turning off of a power supply
current to the TV receiver 3 by a current detector or the like. Further,
the CPU 25 calculates a viewing period by comparing the start time (10:30)
of the movie that is obtained from the in-band data and the present time
(11:35) that is provided by a built-in clock etc. (step S41). More
specifically, the viewing period is calculated as:
##EQU1##
The in-band data is transmitted while being incorporated in a frequency
band of each channel by superimposing it on the audio signal by
amplitude-modulating the FM audio carrier, or by superimposing it on the
18th and 19th blank horizontal flyback lines of the video signal.
Referring to FIG. 13, a structure of the in-band data ID is described. Each
of in-band data ID.sub.1 -ID.sub.4 has link data LD indicating a number of
a channel for the re-viewing after suspension (i.e., a channel to be
linked) on which the movie of the same title is scheduled to be broadcast
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