JPH08265600A - Field synchronizing device for video camera - Google Patents

Abstract

PURPOSE: To synchronize the video signal output of a video camera in the interlace system consisting of even and odd fields with a reference field. CONSTITUTION: A field pulse is separated from the composite video signal from the video camera by a field pulse separation part 8b. The phase of this separated field pulse and that of the reference field pulse from a vertical synchronizing signal generation part 11 are compared with each other by a comparison part (EX-NOR) 8c. If they coincide with each other, a required vertical pulse is generated from a vertical pulse generation part 8d and is sent to the camera 1 side. The phase of the vertical synchronizing signal of the camera output composite video signal is changed by this vertical pulse. This vertical pulse is continuously sent till both field pulses coincide with each other by this phase change, and generation of the vertical pulse is stopped at the time of coincidence. The vertical synchronizing signal generation part 11 is used in common to synchronize the fields of cameras with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field synchronization device for a video camera, and more particularly, in a video signal of an interlace type video camera consisting of an even field and an odd field, the video output of the camera is used as a reference field. Or a device for matching fields between cameras when there are a plurality of cameras.

[0002]

2. Description of the Related Art FIG. 2 shows a block diagram of a main part of an apparatus (monitoring apparatus or the like) for switching and monitoring a plurality of video cameras. In the figure, a plurality of video cameras (A to N) 21 to 23 are connected to a controller 27 and cables 24 to 26, respectively.
The video signal from each camera taken out by the controller 27 is switched by the switching circuit 28 and monitored by the monitor 29. Here, it is assumed that the video signal output by each video camera is of an interlace system including even fields and odd fields. Each of these cameras has a power supply / image superimposition / separation unit (27a to 27) on the controller 27 side.
The cable is connected to the cable c) and power is supplied from the controller side to the camera side using the same cable in common, and the video signal is sent from the camera side to the controller side. Therefore, the video signal and the power supply are superimposed on each cable.
This power supply and video superimposition and video separation are performed by each power supply / video superimposition / separation unit (this method is referred to as a power supply superposition method). A sync signal (horizontal, vertical) generation circuit is provided on each video camera side, and the video signal output is a composite video signal in which the sync signal and the video component are combined.

Further, a vertical synchronizing signal generating section 27d is provided on the controller 27 side, and each power source / video superimposing / separating section (27
a-27c) to send a vertical sync signal to the camera side,
The vertical cycles of the cameras are matched. This prevents the disturbance of vertical synchronization when the switching circuit 28 switches the image. However, in the case of the interlace system in which the video signal is composed of even fields and odd fields, it cannot be said that a perfect synchronization state is achieved only by matching the vertical cycle described above, and it is necessary to match the fields. When switching the video in which the fields do not match, the image may be disturbed at the time of switching depending on the monitor. Conventionally, this field mismatch is used as it is without any special measures.

[0004]

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a field synchronization device in which the field synchronization of a video camera is performed on the controller side.

[0005]

According to the present invention, a video camera and a controller are connected by a cable, and the composite video signal is transmitted from the video camera side to the controller side while the same cable is commonly used, while the video signal is transmitted from the controller side. In a power supply superimposing type video camera device configured to supply required power to the same video camera side, an equivalent pulse and vertical synchronization inserted in the vertical blanking period of the same signal from the transmitted composite video signal. From a field pulse separation unit that separates a field pulse composed of a signal and a horizontal synchronization signal, a vertical synchronization signal generation unit that generates a reference field pulse, a field pulse separated by the field pulse separation unit, and the vertical synchronization signal generation unit. The comparison section that compares the phase with the reference field pulse of A vertical pulse generator that generates a required vertical pulse only when the phases of both field pulses do not match, and when a vertical pulse is generated by the vertical pulse generator, the vertical pulse is used as a reference from the vertical synchronization signal generator. And a superimposing section for superimposing and outputting the field pulse, and for outputting a reference field pulse when the vertical pulse is not generated, and the output of the superimposing section to the vertical synchronizing signal generating circuit on the video camera side via the cable. The present invention provides a field synchronization device for a video camera, which is adapted to establish field synchronization of a video signal by transmitting.

[0006]

The field pulse separating section separates the field pulse from the composite video signal from the video camera. The separated field pulse and the reference field pulse from the vertical synchronizing signal generating section are compared by the comparing section (EX-NOR) for phase coincidence or non-coincidence. If they do not match in this comparison, the vertical pulse generator generates a required vertical pulse and sends it to the camera side. This vertical pulse changes the phase of the vertical synchronizing signal of the camera output composite video signal. Due to this phase change, the same vertical pulse is continuously sent until both field pulses match, and when they match, the generation of the vertical pulse is stopped. By making the reference field pulse common by the vertical synchronizing signal generator, the fields between the cameras are synchronized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A field synchronization device for a video camera according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an essential part showing an embodiment of a field synchronization device for a video camera according to the present invention, which is composed of a plurality of cameras and a controller. In FIG. 1, 1 to 3 are video cameras A to N and 4 to 6 that output a composite video signal (hereinafter, simply referred to as a video signal) based on the interlace system as in the conventional case, and the video signals and the power supply are superposed on each other. A cable, 7 is a controller for supplying power to each camera via each cable and a video signal is sent from each camera side, and 8 to 10 are first to N-th field synchronization provided corresponding to each camera. Reference numeral 11 denotes a vertical synchronizing signal generator that generates a reference field pulse. Since the internal structure of each field synchronization unit is the same, only the first field synchronization unit 8 is shown and the others are omitted.

In the first field synchronization section 8, 8a is a power supply / video superimposition / separation section for superimposing the power supply Ea and video separation, 8b is a field pulse separation section for separating a field pulse from the separated video signal, 8c is a comparison unit (composed of EX-NOR) for comparing the separated field pulse with the reference pulse from the vertical synchronization signal generation unit 11, and 8d is a comparison unit.
In 8c, a vertical pulse generator that generates the required vertical pulse only when both field pulses do not match, and 8e outputs only the reference pulse from the vertical sync signal generator 11 when no vertical pulse is generated, and the same vertical pulse Is a superimposing section that superimposes on the same reference pulse.

Next, the operation of the present invention will be described. Connecting each camera and each power supply / video superimposing / separating unit on the controller 7 side by a commonly used cable is the same as in FIG. The video signal separated by the same power supply / image superimposing / separating unit 8a is used for the monitor and the field pulse separating unit
Send to 8b to separate field pulse. The same field pulse is composed of an equivalent pulse inserted in the vertical blanking period of the video signal, a vertical sync signal and a horizontal sync signal, and the phase relationship between the even field and the odd field is different. The vertical sync signal generator 11 generates a reference field pulse (reference field pulse) for this field pulse,
This is commonly used in each field synchronization unit.

The comparison unit 8c compares the field pulse on the camera 1 side separated by the field pulse separation unit 8b with the reference field pulse, and detects a match or a mismatch between the two.
As described above, since there is a phase difference between the field pulse in the even field and the field pulse in the odd field, coincidence or non-coincidence can be detected from this difference. When they do not match, a predetermined signal is output. In FIG. 1, the comparison unit 8c is composed of an exclusive NOR gate, and when both field pulses do not match, a "low (L)" output is produced. In addition, instead of the exclusive NOR gate, the exclusive OR gate can detect the match / mismatch. However, in the case of an exclusive OR gate, a "high (H)" output is produced when they do not match, so that matching with the vertical pulse generating section described below may be performed by an appropriate operation with this output.
The vertical pulse generator 8d generates a required vertical pulse (pulse width or the like) based on the signal output when the two field pulses do not match. This pulse may be a single pulse. This vertical pulse is generated only when both field pulses to be compared do not match, and does not occur when they match. When the same vertical pulse occurs, the superimposing section 8e
Is superimposed on the reference field pulse with
It is sent to the camera 1 side via the separating unit 8a and the cable 4.

The vertical phase on the camera 1 side is changed by this vertical pulse. This fluctuating vertical phase video signal is transmitted to the controller 7 side, the field pulse is separated again by the field pulse separating section, and is compared with the reference pulse as described above. By repeating the above, the field phase on the camera side converges (matches) with the phase of the reference field pulse.
I will do it. The vertical pulse continues to be sent to the camera until this convergence occurs, and the generation of the vertical pulse is stopped when both field pulses match. The above description is for the camera 1, but if the reference field pulse generated by the vertical sync signal generator 11 is used in common and the above-mentioned field pulses are matched for each camera, the field between the cameras is changed. Will also match.

[0012]

As described above, according to the present invention, when a plurality of interlace type video cameras each having an even field and an odd field are provided and these video cameras are switched and monitored, the fields between the cameras are matched. be able to. As a result, the conventional problem that the image is disturbed when the camera is switched depending on the monitor is solved, and the range for selecting the monitor is expanded.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts showing an embodiment of a field synchronization device for a video camera according to the present invention.

FIG. 2 is a principal block diagram showing an example of the configuration of a conventional monitor system including a plurality of video cameras.

[Explanation of symbols]

 1 Video Camera A 4 Cable 7 Controller 8 Field Synchronizer 8a Power / Video Superimposing / Separating Unit 8b Field Pulse Separator 8c Comparison Unit 8d Vertical Pulse Generator 8e Superimposing Unit 11 Vertical Sync Signal Generator

Claims (4)

[Claims] 1. A video camera and a controller are connected by a cable, and the same video cable is commonly used to transmit a composite video signal from the video camera side to the controller side.
In a power supply superimposing type video camera device in which required power is supplied from the controller side to the video camera side, the equivalent inserted from the transmitted composite video signal in the vertical blanking period of the signal. A field pulse separation unit that separates a field pulse composed of a pulse, a vertical synchronization signal, and a horizontal synchronization signal, a vertical synchronization signal generation unit that generates a reference field pulse, a field pulse separated by the field pulse separation unit, and the vertical synchronization. A comparator for comparing the phase with a reference field pulse from the signal generator, a vertical pulse generator for generating a required vertical pulse only when the phases of both field pulses in the comparison by the comparator do not match, and the vertical pulse When a vertical pulse is generated by the generator, the vertical pulse is And outputs the superposed on the reference field pulses from the signal generating unit, and a superimposing unit that outputs a reference field pulse in the absence of occurrence of the vertical pulse,
A field synchronization device for a video camera, wherein the output of the superimposing section is sent to a vertical synchronization signal generation circuit on the video camera side via the cable so as to establish field synchronization of a video signal. 2. The field synchronization device for a video camera according to claim 1, wherein the comparison unit is composed of an exclusive NOR gate. 3. The field synchronization device for a video camera according to claim 1, wherein the comparison unit is constituted by an exclusive OR gate. 4. A plurality of video cameras and a controller are connected by a cable for each video camera, and while transmitting the composite video signal from the video camera side to the controller side using the same cable, the controller side is required. In the power source superimposing type video camera device configured to supply the power source to the same video camera side, from the transmitted composite video signal, an equivalent pulse and a vertical synchronizing signal inserted in the vertical blanking period of the same signal. And a field pulse separating section provided for each camera for separating a field pulse consisting of a horizontal synchronizing signal, a vertical synchronizing signal generating section for generating a reference field pulse, a field pulse separated by the field pulse separating section, and Each camera that compares the phase with the reference field pulse from the vertical sync signal generator And a vertical pulse generation section provided for each camera that generates a required vertical pulse only when the phases of both field pulses do not match in the comparison by the comparison section, and the vertical pulse generation section. When a vertical pulse is generated by the unit, the vertical pulse is superimposed on the reference field pulse from the vertical synchronizing signal generation unit and output, and when the vertical pulse is not generated, the reference field pulse is output for each camera. A superimposing circuit provided, and the output of the superimposing circuit is sent to the vertical synchronizing signal generating circuit on the video camera side via each of the cables so that field synchronization is achieved in each video signal of the video camera. Field synchronization device for video cameras.