JPH066798A - Transmission control system for video signal - Google Patents

Abstract

PURPOSE:To effectively control video transmission by connecting plural video cameras with devices sending signals after time-division multiplexing and a master controlling device with one bus line and demodulating a time-division multiplex signal by the master controlling device at the video display. CONSTITUTION:Video cameras 1, 2,...5, for example, perform the time-division multiplexing of video signals. A mask controller 5 connected with these cameras by one bus line performs the sampling of A/D converted video signals and inputs it in a field memory 12. The memory 12 writes the inputted video signal in the prescribed position and reads it out at the output. Thus, the signals from the cameras 1-4 are devided in one field and transmitted so as to superimpose the video signal from an image pickup section 11 of the prescribed size and at the prescribed location. The address are given to the data read out from the memory 12 at the output, which are sent to a line memory 14 then written in the prescribed position by the address given from the memory 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for time-division-multiplexing a video signal and transmitting the same, and a demodulator for demodulating the transmitted time-division-multiplexed signal. Suitable for use as a surveillance system.

[0002]

2. Description of the Related Art In a conventional surveillance system, one bus line can transmit only video signals from one video camera. Therefore, when a plurality of monitoring places are provided, a plurality of bus lines are provided, each video camera is connected to the master control device, and each video camera is remotely controlled by the master control device. The signal processing of the video signal is performed and the video is displayed on a monitor or the like to monitor the condition of the monitoring place.

[0003]

According to the conventional method, the number of connecting cameras also increases with the increase in the number of video cameras that make up the system, which requires a lot of cost for installation work and maintenance and inspection. The present invention relates to installation work and maintenance by connecting a plurality of video cameras equipped with means for transmitting time-division multiplexed video signals and a master control device with one bus line and transmitting the video signals. It is an object of the present invention to provide an economical video signal transmission control system that can save the labor of inspection.

[0004]

FIG. 1 is an electric circuit block diagram of a video signal transmission control system showing an embodiment of the present invention. As shown in FIG. 1, video signals are time-division multiplexed. Video cameras (1-4) equipped with means for sending and receiving
And the master control device 5 are connected by one bus line,
The master controller 5 controls each of the video cameras (1 to 4), demodulates the time-division multiplexed signal and outputs it as a video signal, and inputs it to a monitor 6 or the like for video display. As shown in FIG. 2, the means for time-division-multiplexing and transmitting the signals includes an imaging unit 10, an A / D converter 11 for converting a video signal from the imaging unit 10 into a digital signal,
Field memory 12 for storing the same digital signal
An address control unit 13 for controlling the address of the data read from the field memory 12, and an address control unit 1
A line memory 14 for writing, reading and outputting at a predetermined position according to the address given in 3, and a D / A converter 15 for converting the output from the line memory 14 into an analog signal and sending it to the bus line, A synchronization / command discrimination unit 17 that discriminates and outputs a synchronization signal and a command from a control signal input from the master control device 5 via the bus line, and controls according to an input from the synchronization / command discrimination unit 17. Timing control unit 1 that outputs a signal
8 and controls the image pickup unit 10, the field memory 12, the address control unit 13, and the line memory 14 based on a control signal from the timing control unit 18.

The master control unit 5 is, as shown in FIG.
A / D converter 20 for converting the time-division-multiplexed video signal input via the bus line into a digital signal
An address control unit 21 for address-controlling the digital signal, a field memory 22 for writing, reading and outputting at a predetermined position according to an address given by the address control unit 21, and converting the output into an analog signal. A D / A converter 23 that outputs as a video signal, a timing control unit 24 that outputs a control signal according to an input operation signal, and a circuit that controls the address control unit 21 and the field memory 22 based on the control signal. And a synchronization / command control unit 25 which generates a synchronization signal and a command based on the control signal and sends the command to the bus line.

[0006]

According to the present invention, the video signal of each of the video cameras 1 to 4 is time-division multiplexed and input to the master control unit 5 via the bus line by the above-mentioned configuration, and the master control unit 5 demodulates the time division multiplexed signal. And output as a video signal. 4 (A) and 4 (B) are explanatory views showing the structure of a signal used for transmitting an image according to the present invention. Four video cameras 1 to 4 are used, and each video camera 1 to 4 captures an image. The case where the video signal thus displayed is displayed as four sub-screens on the main screen is shown. FIG. 4A shows the structure of each field. As shown in FIG. 4, signals are transmitted using 525/2 horizontal scanning lines per field, as in a normal television signal. So that each video camera 1
By writing a video signal to the field memory 12 provided in 4, and reading and outputting the video signal, approximately 60 horizontal scanning lines are allocated to the video of one video camera, and the video of four video cameras is recorded in one field. So that it can be transmitted.

FIG. 4B shows the configuration of each horizontal scanning line. As shown in FIG. 4, since the image of each video camera is displayed as a 1/4 child screen on the main screen of the monitor, For example, in the image of one video camera, the number of horizontal scanning lines is thinned out every one line, and the transmission line is set to 1, 3, 5 or less, the horizontal time axis is compressed, and lines 1 and 3 are compressed during 1H. Just as the above two horizontal scanning lines are transmitted, other horizontal scanning lines are transmitted in the same manner. In the master control device 5, the signals are written in the field memory 22 in a predetermined order, read out and output to demodulate the time division multiplexed signal and output as a video signal, and input to the monitor 6 or the like for video display. Therefore, it is possible to connect the plurality of video cameras 1 to 4 and the master control device 5 with one bus line to transmit the video signal.

[0008]

1 is a block diagram of an electric circuit of a video signal transmission control system showing an embodiment of the present invention. 1-4
Is a plurality of video cameras equipped with means for transmitting time-division multiplexed video signals, 5 is a master control device, and one bus line is provided between the video cameras 1 to 4 and the master control device 5. The master control device 5 controls the video cameras 1 to 4 and demodulates the time-division multiplexed signal to output as a video signal, which is input to the monitor 6 or the like to display a video. The condition of the installation site is monitored.

FIG. 2 is an electric circuit block diagram showing means for time-division-multiplexing and transmitting video signals, which are provided in the video cameras 1 to 4 of FIG. Reference numeral 10 denotes an image pickup unit, which converts the state of the monitoring place into a video signal and outputs the video signal, and the A / D converter 11
The video signal input by the A / D converter 11 is sampled, converted into a digital signal, output, and input to the field memory 12. Field memory 12
Then, by writing the input video signal to a predetermined position, reading it, and outputting it, the video signal from the imaging unit 11 can be superimposed at a predetermined position with a predetermined size, as shown in FIG. Thus, the video signals from the video cameras 1 to 4 are divided into one field and transmitted.

Reference numeral 13 denotes an address control unit, which adds an address to the data read from the field memory 12 and outputs the data, and inputs the data to the line memory 14 to input the data to the line memory 1
By writing, reading, and outputting at a predetermined position in accordance with the address given in 4, the horizontal scanning lines of the video signal from the imaging unit 10 are thinned out line by line as shown in FIG. 4B. By compressing the time axis of the direction, the horizontal scanning lines of two video signals are transmitted during 1H. Reference numeral 15 is a D / A converter, which is a line memory 14
The data read from is converted into an analog signal, and the time division multiplexed signal is sent to the bus line via the input / output terminal 16.

Reference numeral 17 denotes a synchronization / command discriminating unit which discriminates and outputs a synchronizing signal and a command from a control signal input from the master control device 5 via a bus line, and outputs them to a timing control unit 18 for timing control. A control signal is output according to the synchronization signal and command input by the unit 18. The control signal is input to the image pickup unit 10, and the image pickup unit 10
In addition to controlling the camera angle of (1), a clock signal for signal processing is supplied, and the control signal is input to the field memory 12 to supply a clock signal for writing and a clock signal for reading. Of the scanning line is superimposed on a predetermined position of the field in a predetermined size, the control signal is input to the address control unit 13, and the number of the scanning line on which the video signal from the imaging unit 10 is superimposed is designated. Further, by inputting the control signal to the line memory 14 and supplying a clock signal for writing and a clock signal for reading, the horizontal scanning lines of the video signal from the image pickup unit 10 are thinned out on the scanning lines of the designated number, and the horizontal direction is set. The time axis of is compressed so that it can be superimposed.

FIG. 3 is a block diagram of the master controller of FIG.
It is an electric circuit block diagram which shows the demodulation device of a time division multiplex signal. Reference numeral 19 denotes an input / output terminal, which is connected to the input / output terminal 16 by one bus line.
A / D converter 20 for the time division multiplexed signal input via
Is input to the address control unit 21. The A / D converter 20 converts the digital signal into a digital signal and outputs the digital signal. The address control unit 21 assigns an address to the input digital signal and outputs it, and inputs it to the field memory 22.
According to the address given in the field memory 22,
The data is written into, read out from, and output to a predetermined position, is input to the D / A converter 23, is converted into an analog signal by the D / A converter 23, and is output as a video signal.
Etc. and input each video camera 1 to the main screen of the monitor 6.
The video signal captured in 4 is displayed as four sub-screens.

A timing control unit 24 outputs a control signal in response to an input operation signal, inputs the control signal to the address control unit 21, and superimposes it on a scanning line of a designated number. An address is given to the video signal from the image pickup unit 10, the control signal is input to the field memory 22 to supply a clock signal for writing and a clock signal for reading, and the video signal from the image pickup unit 10 is supplied to the field memory according to the address. The control signal is input to the synchronization / command control unit 25, the synchronization signal and the command are generated in accordance with the input, and are transmitted to the bus line. In addition,
To increase the number of video cameras installed, refer to Fig. 4.
In FIG. 4A, the number of horizontal scanning lines allocated to the video signal of one video camera is reduced, and the video signal of each video camera is superimposed on one field. The video signals of each video camera may be transmitted by thinning out the horizontal scanning lines of the signals and compressing the horizontal time axis.

[0014]

As described above, according to the present invention,
To connect a plurality of video cameras equipped with means for time-division-multiplexing video signals and the master control device with one bus line, and demodulate the time-division-multiplexed signal by the master control device to display an image. Since the transmission of the video signal is performed by a single bus line, it is possible to provide an economical video signal transmission control method that can save the trouble of installation work and maintenance inspection. .

[Brief description of drawings]

FIG. 1 is a block diagram of an electric circuit of a video signal transmission control system showing an embodiment of the present invention.

FIG. 2 is an electric circuit block diagram showing a means for time-division-multiplexing and transmitting video signals, which is provided in the video camera of FIG.

3 is an electric circuit block diagram showing a time-division multiplexed signal demodulation device provided in the master control device of FIG. 1. FIG.

4A and 4B are explanatory diagrams showing a configuration of a signal used for transmitting an image according to the present invention.

[Explanation of symbols]

 1 video camera 2 video camera 3 video camera 4 video camera 5 master control device 6 monitor 10 imaging unit 11 A / D converter 12 field memory 13 address control unit 14 line memory 15 D / A converter 16 input / output terminal 17 synchronization / Command determination unit 18 Timing control unit 19 Input / output terminal 20 A / D converter 21 Address control unit 22 Field memory 23 D / A converter 24 Timing control unit 25 Synchronization / command control unit

Claims (2)

[Claims] 1. A plurality of video cameras equipped with a means for time-division multiplexing and transmitting video signals and a master control device are connected by a bus line, and each master control device controls each video camera and is time-division multiplexed. A device for demodulating a multiplexed signal and outputting it as a video signal, inputting it to a monitor or the like for video display, and means for time-division-multiplexing and sending out the video signal is provided by an imaging unit and an imaging unit. An A / D converter that converts a video signal into a digital signal, a field memory that stores the digital signal, an address control unit that controls the address of data read from the field memory,
A line memory that writes, reads, and outputs at a predetermined position according to an address given by the address control unit, and a D / A converter that converts an output from the line memory into an analog signal and sends the analog signal to the bus line. A synchronization / command discrimination unit that discriminates and outputs a synchronization signal and a command from a control signal input from the master control device via the bus line; and a control signal according to an input from the synchronization / command discrimination unit. Composed of a timing control unit for outputting the
A video signal transmission control system comprising: a control unit for controlling the image pickup unit, the field memory, the address control unit, and the line memory. 2. An A / D converter for converting the time-division-multiplexed video signal input via the bus line into a digital signal, and an address control unit for controlling the address of the digital signal by the master control device. And a field memory for writing, reading and outputting at a predetermined position according to the address given by the address control unit, and a D / A for converting the same output into an analog signal and outputting it as a video signal.
A converter, a timing control unit that outputs a control signal according to an input operation signal, a circuit that controls the address control unit and the field memory based on the control signal, and a synchronization signal and a synchronization signal based on the control signal. 2. The video signal transmission control system according to claim 1, further comprising a synchronization / command control unit for generating a command and transmitting it to the bus line.