JPS5977780A - Catv device - Google Patents

Abstract

PURPOSE:To reduce memory capacity for every subscriber terminal and to constitute an efficient CATV system by providing a block control part with a common use still picture memory. CONSTITUTION:A signal from a station 13 is supplied to the block control part 11 which controls some area, and the control part 11 has a still picture memory 10. A still picture control part 9 processes a signal requested from the keyboard 7 of a terminal 12 and sends the resulting signal to a CATV station 13. A figure shows two still picture memories wherein a sent still picture is recorded when they do not use the still picture, but the number of the memories is determined by the number of terminals and utilization efficiency. Signals read out of the memories 10 are RF-modulated to a free channel of a general TV signal and then mixed by a mixer 8, and supplied to the terminal 12, where it is displayed on a TV receiver 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a CATV device that transmits television signals by wire.

Conventional Structure and Problems Conventionally, in CATV, only general programs were broadcast in one direction from the station to terminal devices, which are subscribers. but,
Recently, broadcasting formats that provide still image services in response to requests from subscribers have been considered. Its basic configuration is shown in Figure 1.

General programs from the CA 17 station 1 are supplied to the subscriber's terminal 6 via the transmission line 6 and displayed on the television receiver 3. On the other hand, a request for a still image is made by requesting the desired screen from the keyboard 4 of the terminal. This request signal is transmitted to the CATV station 1 via the transmission path 6, and the center searches for the requested still image, and An address and the like are added, and the data is transmitted via the transmission path 5. The terminal that issued the request records one screen (one frame) with its own address in the image memory 2.゛The signals recorded in the image memory are read out repeatedly,
0 displayed on the television receiver 3. Note that the details of the search function of the CATV station and the surroundings of the still image memory are common and are not directly related to the present invention, so a description thereof will be omitted.

Regarding the transmission line 5, bidirectional transmission is performed, but there are cases where one line is used for both up and down, and there are cases where two lines are used for up and down, respectively, but this is not directly related to the present invention. Therefore, the explanation will be omitted.

Although this kind of still image service is simple and easy to understand, each terminal must have memory for one frame, which currently increases the terminal cost due to the cost of frame memory, which is hindering its widespread use. . In addition, most people watch general broadcasts, and the still image memory is not used very often.

Purpose of the Invention The present invention provides a CATV that provides still image services.
The purpose is to reduce the cost burden of frame memory of each terminal and provide economical still image services.

A block control section that has a function of providing still image services in response to requests from terminals and controls n terminals within a specific block is provided with m still image memories'(m<n).

DESCRIPTION OF EMBODIMENTS The structure of the present invention will be explained with reference to FIG. CATV station 1
The signal from block controller 3 controls a certain area.
1. The block control section 11 is a section that collectively controls about 10 to 60 terminals as one block, and specifically, it is convenient to treat buildings, apartments, etc. as blocks.

The block control unit has a still image memo IJ10,
The number m of memories is made smaller than the number n of terminals. This is based on the probability that the device uses still image memory.
One memory is not necessarily required for one terminal, and one memory can be shared by several terminals. The still image control unit 9 processes the signal requested from the keyboard 7 of the terminal 12 and transmits it to the CATV station 1. Meanwhile, the still image controller 9 finds an unused still image memory and records the transmitted still image in the still image memory. Although only two still image memories 10 are shown in FIG. 2, considering the number of terminals and the probability of use, it is possible that there may be more 0 still image memories 1
The signal read out from o is RF-modulated into an empty channel of a general TV signal in mixer 8, and then mixed, and sent to terminal 1.
2 and displayed on the television receiver 13. The above is the basic configuration of the invention.

In Figure 2, all general TV signals up to the terminal,
A configuration has been described in which the requested signal is supplied as an RF signal and the receiver of the terminal selects the channel. The signal arrangement in that case is the third
Shown in Figure a.

This method requires many channels for still image signals when the number of terminals increases and there are many requests for still images, and even though the terminal side can display which channel the signal will be sent to, there is a limit.

Furthermore, transmitting multiple frequency-multiplexed channels through optical fibers is technically problematic and costly. Therefore, a method can be considered in which the block control section is provided with a channel selection function and the signal is transmitted to the subscriber only on one specific channel. In that case, the frequency array will be as shown in Figure 3.

Further, its configuration is shown in FIG. The common numbers are the same as in FIG.

The channel selection signal or request signal selected with the keyboard 7 of the terminal is transmitted to the control section 14. In the control section, the general program is directly selected by the RF multiplied signal from the CATv station 1 in the channel selection circuit 17, converted to a specific channel, and supplied to the receiver 3 of the terminal.

In the case of a still image request, it is processed by the control unit 14 and CAT
Transmit to V station. The still image signal searched by the CATV station is supplied to the still image memory 10. Which memory to use is controlled by the control unit 14.The signal read from the memory 10 is once modulated into an RF signal by the mixer 8 and input into an empty channel of a general TV signal, and then sent to the selection circuit 17.
is selected, converted to a specific frequency, and supplied to the display section of the terminal.

Another method for processing signals read from the memory 1o is shown in FIG. Since the memory output is a baseband signal, it may be converted by a conversion circuit 15 to a specific frequency, and the controller 14 may switch between the general program and the requested program by switching the electronic switch 16. In this way, there is no need to convert to an empty TV channel, and the capacity of the empty channel does not become a problem.

Effects of the Invention The present invention reduces the amount of memory per subscriber terminal by providing a shared still image memory in the block control section, resulting in an economical CATV system.

Furthermore, by converting to a specific channel in the block control unit, the transmission system becomes compatible with optical fiber transmission. Further, since request signals from all terminals are not directly connected to the CATV station, noise at the center station is reduced. Also, using optical fiber for the subscriber system makes it easy for eavesdropping to occur.
, is effective for pay TV, etc.

[Brief explanation of drawings]

FIG. 1 shows a conventional embodiment of the query possible at C and T.
A diagram showing the frequency arrangement of the V signal, FIG. 3, and a diagram showing the state of the TV signal in FIG. 4. FIG. 4 is a block diagram of a specific embodiment of the present invention, and FIG. 5 is a diagram showing the signal processing system in FIG. 4. 3... Television receiver, 7... Keyboard, 8... Mixer, 9... Still image control unit, 11... Block control unit, 12・Song・Terminal, 13・Song・TV receiver, 14...Control unit,
15...conversion circuit, 16...electronic switch, 17...medium 1 selection circuit.

Claims (1)

[Claims] (1) Having a plurality of block terminals, a plurality of block control units are provided to control n terminals within a specific block terminal in response to requests from each of the block terminals, and each block control unit has m still image memories. An ATV device comprising m (n) terminals and sharing m still image memories among the terminals at the n locations.
C according to claim 1, comprising a channel selection switch that selects multiplexed and transmitted signals, and the selected signal is transmitted to a requested terminal at a specific frequency.
ATV equipment.