JPS596688A - Catv system - Google Patents

Abstract

PURPOSE:To enable sending of more still pictures, by dividing the picture of a still piclture and transmitting only necessary area out of divided areas to a terminal device. CONSTITUTION:When one frame of video signals is taken out, the signals are digitized by an A/D converter and supplied to a memory circuit 63. At this time, a write address signal is supplied from a write address signal forming circuit 74 to the circuit 63 through a switch circuit 77, and video signals of one frame from a converter 62 is written in the circuit 63. Then, the circuit 63 is made to reading mode, and data indicating transmitted area divided from a computer 30 are supplied to an address signal forming circuit 75, and reading address of the transmitted area is supplied to the circuit 63 through the circuit 77. Accordingly, video signals of transmitted area are read out from the circuit 63, converted to analog signal by a D/A converter, and supplied to a composite circuit 65. Terminal code is added in the circuit 65 and sent out from a terminal 66.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a directional CATV system for use in hotels, for example.

For example, in a hotel, each room has an interactive CAT
It is conceivable to prepare a V terminal device (television receiver) and provide the following services to guests.

(1) Viewing TV broadcasts You can watch regular TV broadcasts and CATV broadcasts.

(ii) BGM You can listen to regular FM broadcasts and records.

(iii) Screening of movies Broadcast movies, etc. using a VTR.

(iv) Reservation For example, the menu of the restaurant in the hotel will be displayed on the screen, so you can reserve the food you like along with your seat.

(v) Shopping When the guest makes an instruction using the switch, various products are displayed on the screen and can be purchased.

(vi) Information about movies, theaters, etc. Displays the cast and other information about the movie currently being shown on the screen.

(vii) Absence service When the guest is absent, messages such as visitors and phone calls are displayed on the screen.

(viii) Check out Guests can check the details of their accommodation costs in their room.

(to i) information In the event of a fire, etc., this will be notified to guests.

(x) Others Guidance on how to use this CA 'I' V system, etc.

In this case, items (i) and (iii) must be continuous images as in normal broadcasting (hereinafter referred to as "within one motion"), but items (iv), (vi) to (x) must be still images. That's fine. Regarding item (■), it is effective to combine moving images and still images.

By the way, in a typical hotel, all rooms are wired with a 5C-2V coaxial cable for receiving television broadcasts. Therefore, it would be extremely convenient if the above-mentioned CATV could be implemented using this existing coaxial cable.

However, the upper limit of the transmission band of this coaxial cable is 400
MHz 4%! This is approximately 67 degrees of the TV band.
(67#400/6), and in reality, channels for accessing commands and data between the terminal devices in each room and the CATV center are also required, so there are 50 to 60 channels. It becomes a degree. With such a number of channels, the number of channels is insufficient to realize the above-mentioned items (i) to (x).

Therefore, by solving the problems like -F mentioned (i) ~
A hotel usage directional CATV system that makes item (x) possible is conceivable.

First, let's explain an example. Note that the following example is a case of a hotel CATV system in the United States, and the number of terminal devices is 1024. Further, a video signal and an audio signal in the state of a modulated signal in television broadcasting etc. will be referred to as a television signal.

In Figures 1 and 2, (100') is C within the hotel.
The ATV sending center (200) indicates a terminal device installed in each room, and the center (100) and the terminal device (200) are connected, for example, to a 5C-2V coaxial cable (3
00) and a bidirectional distributor (400).

Then, at the center (100) (Fig. 1), Q
The OI communicates with the headend (QO), which receives a signal indicating a request from the terminal device (200) and sends out a control signal and a television signal that satisfies the request.

Further, (11) indicates a receiving device for receiving general CATV broadcasting outside the hotel, and (12) indicates a receiving device for receiving general TV broadcasting, and these receiving devices (11)
, (12) is composed of, for example, an RF amplifier, and the received TV signal (multiple channels) is subjected to level adjustment, etc., but demodulation is not performed, and the TV signal of the channel at the time of reception is sent to the head end aω. supplied to

Furthermore, (13) shows a receiving device for receiving FM broadcasts, and the FM signals received thereby are also fed to the bed end (101) without being repeated eight times.

Also, (14) plays multiple record players or cassette players, and the audio signals played by these are supplied to the head end 0ω, converted into an FM signal in the same format as FM broadcasting, and then sent to the cable (300). It will be done.

In addition, (15A) and (15B) indicate, for example, a plurality of U-standard videotape players, and the player (15A) constantly plays (iii) rl movies, etc., and the playback signal is sent to the head end 00). Supplied.

In addition, the player (15B) has an image (video image) related to shopping in item (v), and the controller (25B)
), and during reproduction, a coat signal related to the contents of the reproduction screen can also be reproduced from the auxiliary track of the tape. And this player (1
5B) is also supplied to the head end aω.

Further, (16A) and (16B) indicate, for example, a plurality of laser-type video disk players, and from the player (16A), as in the player (15A), (i
The movies and the like mentioned in item ii) are constantly played back, and the playback signal is supplied to the head end (10). Also, the player (
16B) has an image in one frame unit (or one field unit) for terms (iv) to (x), etc., and this is controlled by controller (26) to display one frame J, , and the reproduced signal is supplied to the head end 00). Furthermore, during this playback,
The playback position (frame) is determined by the address signal ttt
It is possible to set the

Further, (17) indicates a plurality of sheet recorders, which record video signals from a video camera (18) frame by frame using, for example, a cassette-type rotating magnetic sheet, and are capable of playing back the video signals. The reproduced video signal is supplied to the head end α0). The sheet recorder (17) is used to reproduce items (iv) to (vii), etc., and has an address similar to a video disc, and is controlled by the controller (27) in approximately one frame units. Further, a video signal from the camera (IFD) is also supplied to the head end 00.

Furthermore, (3(1) indicates a microcomputer of a multi-CPU system, and this computer (30) is connected to the head end Q[l+ and controllers (25) to (27).
), and performs various types of control, such as processing in response to requests from the terminal device (200), as will be described later. The hotel's main computer (50) is also connected to the computer (30).

Further, (41) represents a CRT monitor, and (42) represents a printer, through which monitor results of this CATV system are displayed or printed.

Here, the signals accessed between the center (100) and the terminal device (200) are assigned frequencies as shown in FIG. 3, for example.

In other words, the frequency band 10 to 30MHz is the terminal device (
200) to the center (100), and the band 10 to 20 MHz is a channel for signals indicating requests from the terminal device (200), as will be described later. Hz is a channel for maintenance and inspection of the terminal device (200).

In addition, the frequency band 54 to 402 MHz is centered (10
0) to the terminal device (200), of which the bands 54 to 88 MHz and 17
4-216MHz is the normal television broadcasting band,
CAT received by receiving devices (11) and (12)
The TV signal of V and the normal TV signal (multiple channels) are directly transmitted within this band as described above. Furthermore, although the band 88 to 108 MHz is the band of FM broadcast, the FM broadcast (
(multiple channels) are also transmitted as is within this band. Furthermore, the FM signal from the player (14) is also sent out within this band.

Furthermore, the band 108~120MHz is centered (100MHz).
) is the band of the control signal sent to the terminal device (200). And (
K is the remaining band 120 at the headend α0).
~174MHz and 216~402MI (z, and TV broadcast bands (54~88MHz, 174~216
MHz) and sent to the cable (300).

That is, moving images such as movies played on the players (15A) and (15B) and the video disc player (16A) are played using a specific channel among the remaining channels, for example, an empty channel in the television broadcasting band. Still images of 1 frame played back by the video disc player (16B) and sheet recorder (17) are also transmitted to a specific channel among the remaining channels, for example, band 120 to 174 MH.
z and 216-402 MHz channels (details will be described later).

On the other hand, in the terminal device (200) (Fig. 2),
(201) indicates a microcomputer, which controls the operation of this device (200) and accesses control signals to and from the center (100). Further, (211) indicates a bandpass filter for extracting downlink signals, and (212) indicates a bandpass filter for extracting uplink signals, which are connected to the distributor (400).
connected to. (211) also controls a TV tuner device, which is controlled by the microcomputer (201) and receives necessary signals from among the multiple channels of TV signals sent to it. The signal is demodulated, and the video signal and audio signal are supplied to switch circuits (223) and (224).

Furthermore, (225) indicates a memory device, which has, for example, a semiconductor memory, and records one frame of the video signal from the tuner device (221), and performs still playback in which this is continuously repeated and generated. The generated video signal is supplied to a switch circuit (223).

Further, (222) indicates an FM tuner device, which is also controlled by the computer (201), and among the multiple channels of FM signals sent, the necessary ones are received.
The audio signal is extracted from the audio signal, and the audio signal is supplied to the S-isochil path (224).

And these switch circuits (223), (224
) is controlled by a computer (201).

Furthermore, (226) indicates a character generator,
The video signal is controlled by the computer (201) and is reproduced as characters, numbers, etc.
This is done in the switch circuit (22) in the synthesis circuit (227).
3) is combined with the video signal from 3). The video signal from this synthesis circuit (227) is sent to the television receiver (240).
At the same time, the audio signal from the switch circuit (224) is also supplied to the receiver (240).

In addition, (202) shows a demodulation circuit, and (203) shows a modulation circuit. A control signal sent on the downlink is extracted from the demodulation circuit (202) and supplied to the computer (201), and the control signal sent from the demodulation circuit (202) is supplied to the computer (201). ), the computer (201
) is modulated into the uplink band and passed through the filter (
212) to the cable (300).

Further, (231) indicates a transmitting unit of, for example, an infrared remote control, and (232) indicates its receiving device. The transmitting unit 1-(231) has various switches, as shown in FIG. are provided to guests so that they can receive the services listed in (i) to (x) above. In addition, (233) is Otonbaranbu, (250)
is a printer.

Further, signal access between the center (100) and the terminal device (200) is performed by polling the computer (30).

In other words, for simplicity, 1024 terminal devices (200
) are (101) to (164).

(201) ~ (264) ,... (1601) ~ (
1664), the downlink control signal channels (108 to I20MHz) are divided into 16 channels DSI to DS1g as shown in the upper half of FIG.
64 terminal devices (+01) to (+64) are allocated to one channel DSi (i=1 to 16), such that 64 terminal devices (164) are allocated "ζ".

Then, in each channel DSi, the period τ
1 to τ6→ are repeatedly set, for example, channel DS
1 period τ1, a code specifying the terminal device (101) (for each channel 1, such as No. K is sent)
In S i, a code signal specifying the terminal device ifi:[ijJ is sent out during period τj (j=1 to 64). In this case, this code signal is, for example, a serial fK number of 8 hits, t], 1 hit is 1 msec, and therefore, the period τj is 8 msec, and the period τ' ~ τ
One period of 64 is 512 msec (.-8 msec x 64). In other words, in every channel (all channels), this basic device is sequentially designated every 8 msec - 4" and "ζ512 msec. It will be done.

Ichiriki, 1-l) Same channel (10-20 MII
The same is true for L 6 + -p 7 channels US1 to LIS+6, as shown in the half of FIG.
ζ6 for one channel LJ S I
4 terminal devices (+01:+ ~ (+64J are assigned. Then, for example, in channel (131), the period Ts delayed from 1 to 9 hit periods in the specified period of the terminal device (101) is The channel U is set as the data return period from the terminal device (101).
In S i, the specified period τj of the terminal device (i j)
The period Tj delayed by 9 bit periods from the terminal device (i
j) is considered as the period for returning data from.

That is, if data is sent out during period Tj of channel USi, it is assumed that it is from the terminal device (i j).

Therefore, when control signals are accessed between the center (100) and the terminal device (200), this is done as follows.

Now, for example, the number of a certain terminal device ff1 (200) is (10
2), and from this terminal device (102) to the center (100
), this data is
It is temporarily stored in the computer (201). Then, when polling of the center (100) is performed on channel 051, the signal is transmitted to the center (100).
→ Cable (300) → Distributor (400) → Filter (
211) - demodulation circuit (202) → computer (201)
) is supplied to the computer (201) through the line, and the computer (201) determines whether or not the polling is for the user.No processing is performed unless the poll is for the user. stand by. Note that this waiting time is at most one cycle of polling, that is, 512 msec.

Then, when the terminal device (102) is polled during the period τ2, the stored data is
Computer (201) - Modulation circuit (203) - Filter (212) - Distributor (400) → Cable (300)
-Channel US of the line of center (100)
1 to the center (100), and this data was sent in period T2 on channel US1, so
At the center (100), it is regarded as coming from the terminal device (102) and predetermined processing is performed. In this case, if necessary, the center (100) and the terminal device (10
2) A handshake is performed between the two.

FIG. 6 shows an example of the appearance of this terminal device (200),
The receiver (240) is installed on the stand (rank) (270) and the upper part (271) of the stand (270).
The TV signal system circuit is housed in the stand (270
), a memory device (225), a second input monitor (201), a printer (250), a speaker (not shown), and the like are arranged.

The above-mentioned items (i) to (x) are realized by the following operations. In the following explanation, the number of the terminal device (200) used by the guest is (102'l and -4-).

(i) Viewing TV broadcasts In this case, when the guest turns on the TV switch St of the remote control unit (231), this is determined by the computer (201).

Then, when you turn on the desired channel among the channel switches Sc of the unit (231) (or operate the sweep switch Sw), this is determined by the computer (201), and the tuner device (221) The unit (231) specifies the same channel.

Therefore, a desired one is selected by the tuner device (221) from among the television signals sent out from the center (100), and the video signal and audio signal are transmitted from the tuner device (221) to the switch circuits (223), (224).
) to the receiver (240). Accordingly, guests are free to watch any channel of television broadcasting.

Furthermore, since CATV broadcasting is sent out from the center (100) using vacant channels of normal television broadcasting, this can also be viewed in the same way.

(ii) BGM In this case, when the BGM switch 7 sb of the remote control unit (231) is turned on, this
01), the mode is set to FM broadcast reception mode, and the switch circuit (224) is switched to the state opposite to that shown in FIG. Then, when the sweep switch Sw of the unit (231) is operated, the reception frequency of the tuner device (222) is swept, and when there is an FM broadcast, the sweep is stopped once. Therefore, the user can listen to the desired FM broadcast.

Furthermore, since the audio signal from the player (14) is also converted into an FM signal and sent out, it can be listened to in the same way.

(iii) Screening of Movies Movies are currently being played by the players (15A) and (16A) and are being sent out on a specific channel, so when the movie switch Sm of the remote control unit (231) is turned on, this is displayed on the computer (201). ), the tuner device (221) becomes tuned to that particular channel, and therefore, the movie can be watched on the television receiver (240) in the same way as in the case of item (i).

Incidentally, when a plurality of movies are sent out using a plurality of channels, selection can be made using the channel switch Sc as in the case of item (i).

(X) Others (How to use this system) When you turn on the guide switch Sg of the remote control unit (231),
This is determined by the computer (201), the tuner device (221) is set to the still image channel selection state, and the terminal device (102) is set to the center (10
When polled from 0), a request signal is returned.

Then, at the center (100), in response to this request signal, one frame of the video signal of the image shown in FIG. It is converted and sent out from the center (100). However, at this time, the number of the terminal device (200) (
102) is added.

Then, in the terminal device (102), since the tuner device (221) is tuned to the channel of the one-frame television signal that has been sent out, the television signal is received and the tuner device (221) ) supplies a terminal code to the computer (201). Then, in the computer (201), it is determined from this terminal code whether the television signal is for itself, and the terminal device (102)
Now, since it is a TV signal for oneself, the video signal (l frame) obtained from the tuner device (221) is stored in the memory device fY (225), and this is repeatedly replayed/J: (still playback). Ru. Also,
The switch circuit (223) is connected in a state opposite to that shown in FIG.

Therefore, an image as shown in FIG. 7 is obtained on the receiver (240) of the first image display device (102).

Therefore, when a customer turns on the switch "5" at the bottom of the channel switch Sc of Unisol I-(231), this is sent to the center (100) at the next polling from the center (1 (10)).

Then, in the center (100), one frame of an image (explanatory text) explaining how to use this system is played from the player (16B) as in the case of Fig. 7, and a terminal code is also added to this. sent out. Then, in the terminal device (102), the signal is transmitted to the memory device (
225) and is played repeatedly,
Therefore, a still image of its usage is sent to the receiver (240).
will be displayed.

Then, when the customer turns on the forward switch Sf of the unit (231), the above operation is repeated and explanatory texts are displayed one after another. In addition, unit (231)
When you turn on the bank word Sui Nochi Sr,
The explanation display returns to the previous screen.

(iv) Information on movies, theaters, etc. In this case, by turning on the guide switch Sg, the receiver (240) will display the screen shown in Figure 7, so at this time, turn on "1" of the switches Sc. When turned on, the following operations are similar to those for item (x) above. However, in this case, one frame of image is played back by the sheet recorder (17) instead of the player (16B).

(v) Shopping In this case as well, shopping is carried out by turning on the switch "2" of the switches Sc following the guide switch Sg and following the screen shown in FIG. And in this case,
Players (15B) and (16B) are used together.

That is, in the case of fashion, for example, a video of a fashion show is sent out by the player (15B), and when you find the clothes you like, turn on the enter switch Se of the unit (231), and this is sent to the center (100) by polling. transmitted to.

Then, at the center (100), the player at this time (
The address of the disc of the player (16B) is specified based on address No. 1m being played from the auxiliary track of the tape 15B), and various information regarding clothes when the switch Se is turned on based on that address.
For example, images of fabrics, manufacturers, prices, etc. are played,
Thereafter, in the same manner as described above, the player (16B)
Various information will be provided. Also, if the forward switch Sf of the unit (231) is turned on, the player (15
You will be redirected to the video from A).

When making a purchase, the player (16B) plays an image asking how to purchase (for example, when, how many, etc.), and as in item (x), an interactive unit (23B) is played.
Answer by clicking the switch in 1).

Data such as the price of the product is then stored on a computer (
30) and is also output to the printer (42).

(vi) Reservation Also, when the guide switch Sg is turned on and the screen shown in Figure 7 appears, if you turn on the switch 13 of the switches Sc, the switch S
Every time you turn f on, an image of the dish will be displayed. So, if you turn on the switch Se for the desired dish,
This is ordered.

In addition, seats can be reserved interactively in the same manner as in section (V).

(vii) Absence service In this case, the display lamp (233) of the terminal device (102) is lit by the processing of the computer (30) on the center (100) side. Therefore, when the customer turns on the power of the terminal device (102), a one-frame screen recorded in advance using the camera (18) is generated from the recorder (17), and this is the case in item (x). Similarly, the receiver (240
) is displayed.

Therefore, the customer can know about the guests who are absent.

(viii) Following the checkout guide switch Sg, select “4” of the switches Sc.
”, when polled, it is transmitted to the computer (30), and the main computer (40) sends all charges including lodging expenses and (v) IN shopping charges to the terminal along with the details. Device(
102), and this is output to a printer (250).

Therefore, the customer can know the price and its details in advance, so there is no need to wait at the front desk.

(ix) Information This is a terminal device (which is set in the fth player (16B) by the operation of the computer (30) of the center (100) and which requires the output of an image or camera (18).
It is forcibly sent to 20(+) and displayed.

Furthermore, when outputting from the player (16B), ■
It is sent in frame units and serialized by the memory device (225).

Figure 8 shows the waveform when one frame of video signal (television signal) is sent from the center (100) to the terminal device [102], where ph is the horizontal synchronization pulse, Pv is the vertical synchronization pulse, and BS is the vertical synchronization pulse. In the burst signal, the numbers 1 to 525 are line numbers. As described above, the terminal code TC specifying the terminal device (102) is repeatedly inserted into the 10th line to the 16th line of the vertical blanking period, and this is, for example, a 20-bit serial code. It is a digital signal and consists of an address signal and a control signal that actually designate the terminal device (102).

Then, the terminal device (102) determines that the video signal is sent to itself from the address signal in the terminal code TC, and also stores this video signal in the memory device (225) according to the control signal. It is determined that it is stored and then repeatedly retrieved and provided to the receiver (240).

Therefore, even if this video signal is only one frame, it is sent to a specific terminal device (102) and is continuously reproduced as an image.

FIG. 9 shows the handshake between the center (100) and the terminal device (102). In other words, ■ Center (
100) to the terminal device (102).

■ Data is sent from the terminal device (102) to the center (100).

(2) An acknowledge signal is sent from the center (100) to the terminal device (102).

■ An end code is sent from the terminal device (102) to the center (100).

Then, in (2), the center (100) is executing the necessary processing at the time of transmitting the acknowledge signal.

As described above, in each CATV system, when sending a still image from the center (100) to the terminal device (200), only one frame is sent and this is sent to the terminal device (200).
0), the memory device (225) is used to repeatedly reproduce still images, so the center (1
00) and multiple terminal devices (200)
Even if the capacity of 300) is small, a large number of still images can be transmitted. In other words, since the time required to send one frame of image is 1/30 second, still images can be sent to 30 terminal devices (200) per channel in one second. If one still image is requested for each channel, the still image can be sent to 150 terminal devices (200) per channel. In the example of Fig. 3, the bands (120 to 174 MHz, 216 to 402 MHz)
If MHz) is allocated to still images (videos can be allocated to empty broadcast channels), this is the capacity for 40 channels, so 6000 units (
This means that it is possible to respond to requests from terminal devices (200) (=150 devices x 40 channels). Or, since the operating rate of general telephone lines is usually less than 5%,
In the case of the figure, 120,000 units (= 6,000 units 75%
) can respond to requests from the terminal device (200).

Thus, according to this CATV system, a large number of still images can be sent even with just one coaxial cable (300). Moreover, that coaxial cable (30 (
]) can be done using existing cables, so there is no cost involved.

By the way, when considering the content of still images sent from the center (100) to the terminal device (200) in a dual CATV system, a certain terminal device (200
), the next requested still image may only require changing part of the currently viewed still image.

However, even in this case, in the CATV system described above, ζ sends the entire screen to the terminal device (200) over one frame period.

The present invention focuses on these points and makes it possible to send even more still images.

Therefore, in the present invention, °ζ is, for example, as shown in FIG. Of the divided areas, there are already terminal devices (200
), for example, only the diagonally shaded area DR is transmitted to the terminal device (200).

FIG. 12 shows the circuitry added to the head end (10) of the center (100) for this purpose. Zunawara (62
) is A that converts an analog video signal into a digital video signal.
/D converter (63) is a semiconductor memory circuit having a capacity for one frame, for example, and (64) is a D/A converter that converts a digital video signal into an analog video signal.

(74) is a write address signal forming circuit; (74) is a write address signal forming circuit;
5) is a read address signal forming circuit, and (76) is a memory control circuit, which allows the memory circuit (
63) and its address are controlled. Furthermore, (78) shows a terminal code forming circuit, and in this forming circuit (7th day), the terminal code TC1, that is, actually designates the terminal device (200'), based on the output of the computer (30). Address signals and control signals are formed. In this case, the control signal includes a box code that indicates that the video signal that follows is the one obtained when the screen is divided, and the division area D R to be transmitted is the area divided into eight equal parts. It has data indicating whether it is the second one (in the example of FIG. 10, a code indicating that it is the second one).

Note that the above circuit centered around the memory circuit (63) is as follows:
Although not shown in the figure, a necessary number of them are provided.

Then, when the video signal frame to be transmitted from the player (15B), (16B) or sheet recorder (7) to the terminal device (200) is extracted, this signal is transmitted to the A/D converter (200) through the terminal (61). 62), is digitized, and then supplied to a memory circuit (63). Also, at this time, the control circuit (7
6), the memory circuit (63) is put into the write mode, the switch circuit (77) is put into the state shown in the figure, and the write address signal forming circuit (74) is controlled to form a write address signal, which is sent to the switch circuit. (7
7) to the memory circuit (63). Therefore, one frame of digital video signal from the converter (62) is written into the memory circuit (63).

Subsequently, the control circuit (76) controls the memory circuit (
63) is placed in the read mode, and the switch circuit (77) is placed in a state opposite to that shown in the figure. Further, data (starting address) indicating the transmission area h3iDR is supplied from the computer (30) to the read address signal forming circuit (75) to form a read address of the area DR, which is transmitted to the memory circuit ( 63). Therefore, from the memory circuit (63), the area D
The R digital video signals are sequentially read out.

Then, ζ, this signal is supplied to the converter (64) and converted into an analog video signal of the area DR, and this signal is supplied to the synthesis circuit (65), and a vertical synchronization pulse Pv is added as shown in Fig. 11. At the same time, a computer (3
0), the number of the terminal device (200), a code indicating that the screen is divided, and data specifying the divided area DR are supplied to the terminal code forming circuit (78) to form the °C terminal code TC. and this is supplied to the synthesis circuit (65). Therefore, as shown in FIG. 11, the video signal of the divided region DR having the terminal code TC is obtained from the °C1 synthesis circuit (65), and at this time, the terminal code TC is
) number, that it is a split screen, and its split area DR
It shows.

Then, the video signal is taken out through the terminal (66), and thereafter converted into a television signal and sent out.

On the other hand, FIG. 13 shows the memory device (200) of the terminal device (200).
25). That is, (262) is an A/D converter, (263) is a semiconductor memory circuit having a capacity for one frame, and (264) is an A/D converter. Further, (272'I is a detection circuit for an address signal in the terminal code TC, (273) is a detection circuit for a control signal in the terminal code TC, that is, data regarding division,
(274) is the write address signal ~ J formation circuit, (27
5) is the read address (N number formation circuit, (276>
is a memory control circuit.

Then, when the video signal mentioned in -1- is sent from the center (100), it is taken out from the tuner device (221) and supplied to the A/D converter (262) to be converted into a decile video signal. It is supplied to the memory circuit (263).

Furthermore, the video signal from the tuner device (221) is supplied to the synchronization separation circuit (271) to extract the vertical synchronization pulse Pv, and this pulse Pv is used as a header in the detection circuit (271).
272), (273) and control circuit (2
76). Further, the video signal from the tuner device (221) is supplied to the detection circuit (272), and it is detected from the address signal in the terminal code TC whether or not this video signal has been sent to the user. When the output is a video signal supplied to the control circuit (276) and sent to itself, the following operation is performed.

That is, the video signal from the tuner device (221) is supplied to the detection circuit 1-δ (273), it is detected that the screen is divided, and data indicating the divided area DR is detected, and this data is Write address signal formation circuit (2
74) to form a write address signal for the area DR. Further, at this time, the switch circuit (277') is connected to the state shown in the figure by the control 11-child circuit (276), and the memory circuit (263) is placed in the write mode. Therefore, since the write address signal from the formation circuit 1m (274) is supplied to the memory circuit (263) through the switch circuit (277), the write address signal is sent to the address corresponding to the area DR of the memory circuit (263). The video signal of the area DR is written.

When the writing is finished, the control circuit (27
6), the memory circuit (263) is placed in the read mode, and the switch circuit (277) is placed in a state opposite to that shown in the figure, so that the read address signal from the read address signal forming circuit (275,) is placed in the switch circuit (277). ) is supplied to the memory circuit (263). Therefore, the digital video signal for one frame is repeatedly read out from the memory circuit (263).

This signal is then supplied to a D/A converter (264) and converted into an analog signal, that is, a still image video signal is extracted.

Thus, according to the present invention, the screen of a still image is divided into n equal parts, and only the necessary area DR of the divided areas is divided into n parts by the terminal device (
200), the transmission time can be made shorter and more terminal devices (200) can be connected. Further, from the center (100) to the terminal device (2 (10
) You can also send messages and display them at the bottom of the screen.

Note that the terminal device (200) may be provided with a tuner device dedicated to still image television signals.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 12, and FIG. 13 are system diagrams of an example of the present invention, and FIGS. 3 to 11 are diagrams for explaining the same. (100) is a CA i'V safeter, (200) is a terminal device, and (300) is a coaxial cable. Figure 18 Figure 1 Figure 11 (DR))

Claims (1)

[Claims] A CATV center and multiple terminal devices are connected by a common cable, and the CATV center and multiple terminal devices are connected by a common cable, and the CATV center
The still image is transmitted from the TV center to the requested terminal device through the cable, and the static τI:
Il! A CATV system that divides the li screen and transmits an area on the other side of the divided area that is different from the screen that has already been transmitted.